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THE ANALYSIS OF SENSATIONS
THE
ANALYSIS OF SENSATIONS
AND THE RELATION OF THE
PHYSICAL TO THE PSYCHICAL
BY
DR ERNST MACH
EMERITUS PROFESSOR IN THE UNIVERSITY OF VIENNA
TRANSLATED FROM THE FIRST GERMAN EDITION
BY
C. M. WILLIAMS
REVISED AND SUPPLEMENTED FROM THE
FIFTH GERMAN EDITION
BY
SYDNEY WATERLOW, M.A.
CHICAGO AND LONDON
THE OPEN COURT PUBLISHING COMPANY
1914
c **
Copyright in Great Britain under the Act of 1911
TRANSLATOR'S NOTE
THIS book is not so much a new edition of the
English translation of Professor Mach's Contri-
butions to the Analysis of the Sensations^ which was
published in 1897, 1 but is, as the more comprehensive title
indicates, an almost entirely new book. The Contributions
originally appeared in 1886. The English translation of
1897 contained a certain amount of new matter, most of
which was embodied by Professor Mach in his second
edition (1900). Since then there have been three more
editions : two of them, the third and the fifth, containing
important changes and additions of such extent that the
fifth edition, of which this translation is now offered to the
English-speaking public, is a book nearly twice as long as
the original English translation.
It may therefore be convenient to mention here the
principal respects in which this book differs from the
translation of 1897. Six chapters are entirely new,
namely, Chapter III., on "My Relation to Richard
Avenarius and other Thinkers " ; Chapter V., on " Physics
and Biology : Causality and Teleology " ; Chapter VIII., on
" The Will " j Chapter IX., on " Biologico-teleological Con-
siderations as to Space " ; Chapter XI., on " Sensation,
1 Contributions to the Analysis of the Sensations, by Dr. Ernst Mach.
Translated by C. M. Williams. Chicago : Open Court Publishing Co.,
1897-
5C547B
vi THE ANAL YSIS OF SENS A TIONS
Memory and Association," and Chapter XV., on " How my
Views have been received." Further, the eight chapters of
the original edition have all been greatly expanded. Chapter
II. now contains most of the matter which appeared as an
appendix to the translation of 1897. Chapter VII. contains
six sections by Dr. Josef Pollak on recent research as to
the functions of the labyrinth of the ear.
It will be seen that the changes and additions fall, on
the whole, into two classes. They are made with the
object either of amplifying and bringing up to date the
author's original discussions of points of detail, or of
explaining and justifying his more general views as to the
relation between different branches of science and as to
questions on the borderland between science and philo-
sophy. It ill becomes a translator to indulge the temptation,
which he yet must feel, to turn commentator or eulogist ;
but I may perhaps be allowed to point out the great
interest attaching to the explanations here given by the
veteran physicist and philosopher (if Professor Mach will
allow the word "philosopher") of the way in which his
views were developed.
For those parts of the text which are identical with the
English edition of 1897 I have availed myself largely of
Miss Williams's excellent translation. Finally, I must add
that the whole of the present translation has been most
kindly read, in manuscript, by Professor Mach himself.
SYDNEY WATERLOW
28 JOHN STREET, BEDFORD Row,
LONDON, W.C.
AUTHOR'S PREFACES
PREFACE TO THE FIFTH EDITION
r I A HE text of this edition has been enlarged by a number
-L of new passages and notes. There is an insertion
of some length on recent investigations as to the sense of
orientation ; this is from the pen of Professor Josef Pollak,
who has also been so kind as to read the proofs of the
whole book and to correct the index. For all these services
I owe him my heartiest thanks. A mistake as to Ewald's
theory of audition has been corrected. I have noted with
satisfaction that a view of the relation between the physical
and the psychical, which is almost identical with the view
advocated here, occurs in a book by Alfred Binet (DAme
et le Corps, Paris, 1905).
VIENNA, May 1906
PREFACE TO THE FIRST EDITION
THE frequent excursions which I have made into this
province have all sprung from the profound con-
viction that the foundations of science as a whole, and of
vii
viii THE ANALYSIS OF SENSATIONS
physics in particular, await their next greatest elucidations
from the side of biology, and especially from the analysis
of the sensations.
I am aware, of course, that I have succeeded in con-
tributing but little to the attainment of this end. The very
fact that my investigations have been carried on, not in
the way of a profession, but only at odd moments, and
frequently only after long interruptions, must detract
considerably from the value of my scattered publications,
or perhaps even lay me open to the silent reproach of
desultoriness. So much the more, therefore, am I under
especial obligations to those investigators, such as E.
Hering, V. Hensen, W. Preyer and others, who have
directed attention either to the matter of my writings or to
my methodological expositions.
The present compendious and supplementary present-
ation of my views will, perhaps, place my attitude in a
somewhat more favorable light, for it will be seen that in
all cases I have had in mind the same problem, no matter
how varied or numerous were the single facts investigated.
Although I can lay no claim whatever to the title of
physiologist, and still less to that of philosopher, yet I
venture to hope that the work thus undertaken, purely from
a strong desire for self-enlightenment, by a physicist
unconstrained by the conventional barriers of the
specialist, may not be entirely without value for others
also, even though I may not be everywhere in the
right.
My natural bent for the study of these questions received
its strongest stimulus twenty-five years ago from Fechner's
Elemente der Psychophysik (Leipzig, 1860), but my greatest
A UTHORS PREFA CES ix
assistance was derived from Bering's solution of the two
problems referred to on pages 69 and 168.
To readers who, for any reason, desire to avoid more
general discussions, I recommend the omission of the
first and last chapters. For me, however, the conception
of the whole and the conception of the parts are so
intimately related that I should scarcely be able to separate
them.
PRAGUE, November 1885
PREFACE TO THE SECOND EDITION
THIS book was intended to have the effect of an
aper$u, and, if I may judge from the occasional
utterances of Avenarius, H. Cornelius, James, Kiilpe, Loeb,
Pearson, Petzoldt, Willy, and others, it seems to have
fulfilled its object. It now appears, after fourteen years, in
a new edition. This is a rather bold undertaking. For to
allow the book to swell out into a bulky volume, by adding
accounts of many experimental researches on points of
detail, and by noticing at length the literature which has
appeared since it was first published, would not be in
keeping with its character. Yet I was unwilling to let slip
this last opportunity without once again saying something
on a subject which I have so much at heart. I have
therefore added the supplements and elucidations most
urgently required, principally by inserting short chapters in
the original text. one of these, the second, has already
appeared in the English edition published in 1897.
x THE ANALYSIS OF SENSATIONS
one and the same view underlies both my epistemo-
logico-physical writings and my present attempt to deal
with the physiology of the senses the view, namely, that
all metaphysical elements are to be eliminated as super-
fluous and as destructive of the economy of science. If I
have not entered in these pages upon a detailed critical
and polemical discussion of views that are opposed to my
own, this is in truth not from contempt of my opponents,
but because I am convinced that questions of this kind
cannot be decided by controversies and dialectic combats.
The only really profitable course is to carry one's half-
thought or, it may be, one's paradoxical idea patiently
about with one for years, and to make an honest effort to
complete the half-thought, or to strip away the paradoxical
element, as the case may be. Those readers who, after
turning over the first pages, lay the book aside, because
their convictions are such that they cannot follow me any
further, will only be doing exactly what I myself have
sometimes been compelled to do.
In its former shape the book met with much friendly
acceptance, but it also aroused strenuous opposition.
Readers who wish to go more deeply into the subjects of
which it treats, may find it useful to know that Willy, in
a recently published work (Die Krisis in der Psychologic,
Leipzig, 1899), in which a position closely allied to my
own is adopted, opposes my views in many points of
detail.
VIENNA, April 1900
A UTHOR'S PREFA CES xi
PREFACE TO THE THIRD EDITION
/""CONTRARY to my expectation, the second edition
V^/ was exhausted in a few months. I have not
hesitated to make certain additions which may help to put
my views in a clearer light, though without altering the
text of 1886 in any essential respect. Two passages only
of the second edition (paragraph 7, p. n, and paragraph n,
p. 15) have been cast in a clearer form. Dr. A. Lampa,
lecturer in physics in this University, was told by several
readers that these passages were often understood in a one-
sided idealistic sense, an interpretation which I in no wise
intended. I am greatly obliged to Dr. Lampa for giving
me this information. Chapters IX. and XV., in which
subjects touched upon in the second edition are developed
at greater length, are new additions.
Unless all indications are deceptive, I no longer occupy,
as regards my views, anything like so isolated a position
as I did even a few years ago. In addition to the school
of Avenarius, there are also younger thinkers, such as
H. Gomperz, who are approaching my point of view by
their own paths. The differences that still remain over
seem to me not irreconcilable. But it would be premature
to dispute about them yet. " But the question is one in
which it is peculiarly difficult to make out precisely what
another man means, and even what one means oneself."
The author of this delightfully humorous remark was
W. K. Clifford, the mathematician (on the Nature of
Things-in-themselves," Lectures^ vol. ii. p. 88), a writer with
xii THE ANALYSIS OF SENSATIONS
an extremely close affinity to myself in the direction of his
thought.
VIENNA, November 1901
PREFACE TO THE FOURTH EDITION
THE opinion, which is gradually coming to the front,
that science ought to be confined to the compendious
representation of the actual, necessarily involves as a
consequence the elimination of all superfluous assumptions
which cannot be controlled by experience, and, above all,
of all assumptions that are metaphysical in Kant's sense.
If this point of view is kept firmly in mind in that wide field
of investigation which includes the physical and the
psychical, we obtain, as our first and most obvious step, the
conception of the sensations as the common elements of
all possible'physical and psychical experiences, which merely
consist in the different kinds of ways in which these
elements are combined, or in their dependence on one
another. A whole series of troublesome pseudo-problems
at once disappears. The aim of this book is not to put
forward any system of philosophy, or any comprehensive
theory of the universe. It is only the consequences of
this single step, to which any number of others may be
attached, that are examined here. An attempt is made,
not to solve all problems, but to reach an epistemological
position which shall prepare the way for the co-operation
of special departments of research, that are widely removed
A UTHORS PREFA CES xiii
from one another, in the solution of important problems of
detail.
It is from this point of view that the accounts of special
investigations, which are given here, should be regarded.
If there is no essential difference between the physical and
the psychical, we shall hope to trace the same exact
connexion, which we seek in everything that is physical, in
the relations between the physical and the psychical also.
We then expect to find, corresponding to all the details
which physiological analysis can discover in the sensa-
tions, as many details of physical nerve-process. I have
tried to describe this relation, so far as I have been able
to do so,
ｅxpressions of extravagant praise and of equally extra-
vagant blame, have come to my ears. I hope that what
I have just said, by moderating both, may promote a sober
judgment. When, about thirty-five years ago, I succeeded,
by overcoming my own prejudices, in firmly establishing
my present position and in setting myself free from the
greatest intellectual discomfort of my life, I attained
thereby to a certain satisfaction. At that time I was only
acquainted with Kant and Herbart. To-day I see that a
whole host of philosophers positivists, critical empiricists,
adherents of the philosophy of immanence, and certain
isolated scientists as well have all, without any know-
ledge of one another's work, entered upon paths which, in
spite of all their individual differences, converge almost
towards one point. If, in these circumstances, I cannot
rate very high the value of my individual labours, I may
nevertheless be permitted to believe that I have not merely
pursued a subjective phantom, but have contributed
xiv THE ANALYSIS OF SENSATIONS
towards the attainment of a goal at which many others
besides myself have been aiming. It would of course be
absurd, where ideas are concerned of which the leading
threads reach back to antiquity, to set up any claims to
priority.
Dr. Josef Pollak and Dr. Wolfgang Pauli, lecturers in the
Faculty of Medicine in the University of Vienna, have been
so extremely kind as to read the proofs, for which I thank
them most heartily.
VIENNA, November 1902
CONTENTS
CHAP. PAGE
I. INTRODUCTORY REMARKS : ANTIMETAPHYSICAL . i
II. on PRECONCEIVED OPINIONS . . . .38
III. MY RELATION TO RICHARD AVENARIUS AND OTHER
THINKERS ...... 46
IV. THE CHIEF POINTS OF VIEW FOR THE INVESTIGA-
TION OF THE SENSES . . . -57
V. PHYSICS AND BIOLOGY : CAUSALITY AND TELEOLOGY 83
VI. THE SPACE-SENSATIONS OF THE EYE . . .102
VII. FURTHER INVESTIGATION OF SPACE-SENSATIONS . 122
VIII. THE WILL ...... 171
IX. BlOLOGICO - TELEOLOGICAL CONSIDERATIONS AS TO
SPACE . . . . . .181
X. THE RELATIONS OF THE SIGHT-SENSATIONS TO onE
ANOTHER AND TO OTHER PSYCHICAL ELEMENTS 195
XI. SENSATION, MEMORY AND ASSOCIATION . . 235
XII. THE SENSATION OF TIME .... 245
XIII. THE SENSATIONS OF TONE .... 262
XIV. INFLUENCE OF THE PRECEDING INVESTIGATIONS on
OUR CONCEPTION OF PHYSICS . . . 310
XV. HOW MY VIEWS HAVE BEEN RECEIVED . . 354
INDEX OF SUBJECTS ..... 373
INDEX OF NAMES ..... 377
I. INTRODUCTORY REMARKS:
ANTIMETAPHYSICAL.
i.
THE great results achieved by physical science in
modem times results not restricted to its own
sphere but embracing that of other sciences which em-
ploy its help have brought it about that physical ways
of thinking and physical modes of procedure enjoy on
all hands unwonted prominence, and that the greatest
expectations are associated with their application. In
keeping with this drift of modern inquiry, the physiology of
the senses, gradually abandoning the method of investigat-
ing sensations in themselves followed by men like Goethe,
Schopenhauer, and others, but with greatest success by
Johannes Miiller, has also assumed an almost exclusively
physical character. This tendency must appear to us as
not altogether appropriate, when we reflect that physics,
despite its considerable development, nevertheless con-
stitutes but a portion of a larger collective body of know-
ledge, and that it is unable, with its limited intellectual
implements, created for limited and special purposes, to
exhaust all the subject-matter in question. Without
renouncing the support of physics, it is possible for
the physiology of the senses, not only to pursue its own
2 THE ANALYSIS OF SENSATIONS
course of development, but also to afford to physical science
itself powerful assistance. The following simple con-
siderations will serve to illustrate this relation between
the two.
2.
Colors, sounds, temperatures, pressures, spaces, times,
and so forth, are connected with one another in manifold
ways ; and with them are associated dispositions of mind,
feelings, and volitions. Out of this fabric, that which is
relatively more fixed and permanent stands prominently
forth, engraves itself on the memory, and expresses itself in
language. Relatively greater permanency is exhibited, first,
by certain complexes of colors, sounds, pressures, and so
forth, functionally connected in time and space, which
therefore receive special names, and are called bodies.
Absolutely permanent such complexes are not.
My table is now brightly, now dimly lighted. Its
temperature varies. It may receive an ink stain. one of
its legs may be broken. It may be repaired, polished, and
replaced part by part. But, for me, it remains the table at
which I daily write.
My friend may put on a different coat. His countenance
may assume a serious or a cheerful ｅxpression. His
complexion, under the effects of light or emotion, may
change. His shape may be altered by motion, or be
definitely changed. Yet the number of the permanent
features presented, compared with the number of the
gradual alterations, is always so great, that the latter may
be overlooked. It is the same friend with whom I take my
daily walk.
THE ANALYSIS OF SENSATIONS 3
My coat may receive a stain, a tear. My very manner
of expressing this shows that we are concerned here with
a sum-total of permanency, to which the new element is
added and from which that which is lacking is subsequently
taken away.
Our greater* intimacy with this sum-total of permanency,
and the preponderance of its importance for me as con-
trasted with the changeable element, impel us to the partly
instinctive, partly voluntary and conscious economy of
mental presentation and designation, as expressed in
ordinary thought and speech. That which is presented in
a single image receives a single designation, a single name.
Further, that complex of memories, moods, and feelings,
joined to a particular body (the human body), which is
called the " I " or "Ego," manifests itself as relatively
permanent. I may be engaged upon this or that subject,
I may be quiet and cheerful, excited and ill-humored.
Yet, pathological cases apart, enough durable features
remain to identify the ego. Of course, the ego also is only
of relative permanency.
The apparent permanency of the ego consists chiefly
in the single fact of its continuity, in the slowness of its
changes. The many thoughts and plans of yesterday that
are continued to-day, and of which our environment in
waking hours incessantly reminds us (whence in dreams the
ego can be very indistinct, doubled, or entirely wanting),
and the little habits that are unconsciously and involuntarily
kept up for long periods of time, constitute the groundwork
of the ego. There can hardly be greater differences in the
egos of different people, than occur in the course of years
in one person. When I recall to-day my early youth, I
4 THE ANALYSIS OF SENSATIONS
should take the boy that I then was, with the exception of
a few individual features, for a different person, were it not
for the existence of the chain of memories. Many an
article that I myself penned twenty years ago impresses
me now as something quite foreign to myself. The very
gradual character of the changes of the body also contributes
to the stability of the ego, but in a much less degree than
people imagine. Such things are much less analysed and
noticed than the intellectual and the moral ego. Personally,
people know themselves very poorly. 1 When I wrote these
lines in 1886, Ribot's admirable little book, The Diseases
of Personality (second edition, Paris, 1888, Chicago, 1895),
was unknown to me. Ribot ascribes the principal r61e in
preserving the continuity of the ego to the general sensibility.
Generally, I am in perfect accord with his views. 2
The ego is as little absolutely permanent as are bodies.
That which we so much dread in death, the annihilation
of our permanency, actually occurs in life in abundant
measure. That which is most valued by us, remains
preserved in countless copies, or, in cases of exceptional
1 once, when a young man, I noticed in the street the profile of a face
that was very displeasing and repulsive to me. I was not a little taken
aback when a moment afterwards I found that it was my own face which,
in passing by a shop where mirrors were sold, I had perceived reflected
from two mirrors that were inclined at the proper angle to each other.
Not long ago, after a trying railway journey by night, when I was
very tired, I got into an omnibus, just as another man appeared at the
other end. ' ' What a shabby pedagogue that is, that has just entered,"
thought I. It was myself: opposite me hung a large mirror. The
physiognomy of my class, accordingly, was better known to me than
my own.
2 Cp. Hume, Treatise on Human Nature, Vol. I. part iv., p. 6 ;
Gruithuisen, Beitragc zur Physiognosie und Eautognosie, Munich,
1812, pp. 37-58.
THE ANALYSIS OF SENSATIONS 5
excellence, is even preserved of itself. In the best human
being, however, there are individual traits, the loss of which
neither he himself nor others need regret. Indeed, at
times, death, viewed as a liberation from individuality, may
even become a pleasant thought. Such reflections of
course do not make physiological death any the easier to
bear.
After a first survey has been obtained, by the formation
of the substance-concepts "body" and "ego" (matter and
soul), the will is impelled to a more exact examination of
the changes that take place in these relatively permanent
existences. The element of change in bodies and the ego,
is in fact, exactly what moves the will T to this examination.
Here the component parts of the complex are first exhibited
as its properties. A fruit is sweet ; but it can also be
bitter. Also, other fruits may be sweet. The red color
we are seeking is found in many bodies. The neighbor-
hood of some bodies is pleasant; that of others,
unpleasant. Thus, gradually, different complexes are
found to be made up of common elements. The visible,
the audible, the tangible, are separated from bodies. The
visible is analysed into colors and into form. In the
manifoldness of the colors, again, though here fewer in
number, other component parts are discerned such as
the primary colors, and so forth. The complexes are
disintegrated into elements, 2 that is to say, into their
ultimate component parts, which hitherto we have been
1 Not to be taken in the metaphysical sense.
2 If this process be regarded as an abstraction, the elements, as we
shall see, do not thereby lose anything of their importance. Cp. the
subsequent discussion of concepts in Chapter XIV.
6 THE ANALYSIS OF SENSATIONS
unable to subdivide any further. The nature of these
elements need not be discussed at present ; it is possible
that future investigations may throw light on it. We
need not here be disturbed by the fact that it is easier for
the scientist to study relations of relations of these
elements than the direct relations between them.
The useful habit of designating such relatively permanent
compounds by single names, and of apprehending them by
single thoughts, without going to the trouble each time of
an analysis of their component parts, is apt to come into
strange conflict with the tendency to isolate the component
parts. The vague image which we have of a given per-
manent complex, being an image which does not perceptibly
change when one or another of the component parts is taken
away, seems to be something which exists in itself. Inas-
much as it is possible to take away singly every constituent
part without destroying the capacity of the image to stand
for the totality and to be recognised again, it is imagined
that it is possible to subtract all the parts and to have
something still remaining. Thus naturally arises the philo-
sophical notion, at first impressive, but subsequently re-
cognized as monstrous, of a "thing-in-itself," different from
its "appearance," and unknowable. 1
r Thing, body, matter, are nothing apart from the combi-
lations of the elements, the colors, sounds, and so forth
Cp. W. Schuppe's polemic against Ueberweg, printed in Brasch's
Welt-iind Lebensanschauung Ueber-wegs, Leipzig, 1889; F.J. Schmidt,
Das Aergernis der Philosophic: eine Kantstudie, Berlin, 1897.
THE ANALYSIS OF SENSATIONS 7
nothing apart from their so-called attributes. That
protean pseudo-philosophical problem of the single thing
with its many attributes, arises wholly from a misinter-
pretation of the fact, that summary comprehension and
precise analysis, although both are provisionally justifiable
and for many purposes profitable, cannot be carried on
simultaneously. A body is one and unchangeable only so
long as it is unnecessary to consider its details. Thus
both the earth and a billiard-ball are spheres, if we are
willing to neglect all deviations from the spherical form, and
if greater precision is not necessary. But when we are
obliged to carry on investigations in orography or micro-
scopy, both bodies cease to be spheres.
Man is pre-eminently endowed with the power of volun-
tarily and consciously determining his own point of view.
He can at one time disregard the most salient features of
an object, and immediately thereafter give attention to its
smallest details ; now consider a stationary current, without
a thought of its contents (whether heat, electricity or fluidity),
and then measure the width of a Fraunhofer line in the
spectrum ; he can rise at will to the most general abstrac-
tions or bury himself in the minutest particulars. Animals
possess this capacity in a far less degree. They do not
assume a point of view, but are usually forced to it by their
sense-impressions. The baby that does not know its father
with his hat on, the dog that is perplexed at the new coat
of its master, have both succumbed in this conflict of
points of view. Who has not been worsted in similar
8 THE ANALYSIS OF SENSATIONS
plights ? Even the man of philosophy at times succumbs,
as the grotesque problem, above referred to, shows.
In this last case, the circumstances appear to furnish
a real ground of justification. Colors, sounds, and the
odors of bodies are evanescent. But their tangibility, as
a sort of constant nucleus, not readily susceptible of
annihilation, remains behind; appearing as the vehicle
of the more fugitive properties attached to it. Habit,
thus, keeps our thought firmly attached to this central
nucleus, even when we have begun to recognize that seeing
hearing, smelling, and touching are intimately akin in
character. A further consideration is, that owing to the
singularly extensive development of mechanical physics a
kind of higher reality is ascribed to the spatial and to the
temporal than to colors, sounds, and odors ; agreeably to
which, the temporal and spatial links of colors, sounds,
and odors appear to be more real than the colors, sounds
and odors themselves. The physiology of the senses,
however, demonstrates, that spaces and times may just as
appropriately be called sensations as colors and sounds.
But of this later.
Not only the relation of bodies to the ego, but the ego
itself also, gives rise to similar pseudo- problems, the
character of which may be briefly indicated as follows :
Let us denote the above-mentioned elements by the
letters A B C . . ., K L M . . '., /.*. Let those
complexes of colors, sounds, and so forth, commonly
called bodies, be denoted, for the sake of clearness, by
THE ANALYSIS OF SENSATIONS 9
ABC. . . ; the complex, known as our own body, which
is a part of the former complexes distinguished by certain
peculiarities, may be called K L M . . . ; the complex
composed of volitions, memory-images, and the rest, we
shall represent by a /3 7 ... Usually, now, the complex
a /5 7 . . . K L M . . ., as making up the ego, is opposed
to the complex ABC. . ., as making up the world of
physical objects ; sometimes also, a /3 y ... is viewed as
ego, and-ATZJ/. . .ABC. ..as world of physical'
objects. Now, at first blush, ABC. . . appears inde-
pendent of the ego, and opposed to it as a separate exist-
ence. But this independence is only relative, and gives
way upon closer inspection. Much, it is true, may change
in the complex a j8 y . . . without much perceptible change
being induced in ABC-. . . ; and vice versa. But many
changes in a (3 y ... do pass, by way of changes in
K L M . . ., to ABC. . .; and vice versa. (As, for
example, when powerful ideas burst forth into acts, or when
our environment induces noticeable changes in our body.)
At the same time the group K L M . . . appears to be more
intimately connected with a /3 y . . . and with ABC. . .,
than the latter with one another ; and their relations find
their ｅxpression in common thought and speech.
Precisely viewed, however, it appears that the group
A B C ... is always codetermined by K L M. A cube
when seen close at hand, looks large ; when seen at a
distance, small ; its appearance to the right eye differs from
its appearance to the left ; sometimes it appears double ;
with closed eyes it is invisible. The properties of one and
the same body, therefore, appear modified by our own
body; they appear conditioned by it. But where, now,
lo THE ANALYSIS OF SENSATIONS
is that same body, which appears so different? All that can
be said is, that with different KL M different ABC. . .
are associated. 1
A common and popular way of thinking and speaking
is to contrast " appearance " with " reality." A pencil
held in front of us in the air is seen by us as straight;
dip it into the water, and we see it crooked. In the latter
case we say that the pencil appears crooked, but is in
reality straight. But what justifies us in declaring one
fact rather than another to be the reality, and degrading
the other to the level of appearance ? In both cases we
have to do with facts which present us with different com-
binations of the elements, combinations which in the two
cases are differently conditioned. Precisely because of
its environment the pencil dipped in water is optically
crooked; but it is tactually and metrically straight. An
image in a concave or flat mirror is only visible, whereas
under other and ordinary circumstances a tangible body
as well corresponds to the visible image. A bright surface
1 A long time ago (in the Vierteljahrsschrift fur Psychiatric^ Leipzig
and Neuwied, 1868, art. " Ueber die Abhangigkeit der Netzhautstellen
von einander") I enunciated this thought as follows : The ｅxpression
" sense-illusion" proves that we are not yet fully conscious, or at least
have not yet deemed it necessary to incorporate the fact into our
ordinary language, that the senses represent things neither "wrongly nor
correctly. All that can be truly said of the sense-organs is, that, under
different circumstances they produce different sensations and perceptions.
As these "circumstances," now, are extremely various in character,
being partly external (inherent in the objects), partly internal (inherent
in the sensory organs), and partly interior (having their activity in the
central organs), it can sometimes appear, when we only notice the
external circumstances, as if the organ acted differently under the
same conditions. And it is customary to call the unusual effects,
deceptions or illusions.
THE ANALYSIS OF SENSATIONS n
is brighter beside a dark surface than beside one brighter
than itself. To be sure, our expectation is deceived when,
not paying sufficient attention to the conditions, and sub-
stituting for one another different cases of the combination,
we fall into the natural error of expecting what we are
accustomed to, although the case may be an unusual one.
The facts are not to blame for that. In these cases, to
speak of "appearance" may have a practical meaning,
but cannot have a scientific meaning. Similarly, the
question which is often asked, whether the world is real
or whether we merely dream it, is devoid of all scientific
meaning. Even the wildest dream is a fact as much as
any other. If our dreams were more regular, more con-
nected, more stable, they would also have more practical
importance for us. In our waking hours the relations of
the elements to one another are immensely amplified in
comparison with what they were in our dreams. We
recognize the dream for what it is. When the process
is reversed, the field of psychic vision is narrowed; the
contrast is almost entirely lacking. Where there is no
contrast, the distinction between dream and waking,
between appearance and reality, is quite otiose and
worthless.
The popular notion of an antithesis between appearance
and reality has exercised a very powerful influence on
scientific and philosophical thought. We see this, for
example, in Plato's pregnant and poetical fiction of the
Cave, in which, with our backs turned towards the fire,
we observe merely the shadows of what passes (Reptiblic,
vii. i). But this conception was not thought out to its
final consequences, with the result that it has had an
12 THE ANALYSIS OF SENSATIONS
unfortunate influence on our ideas about the universe.
The universe, of which nevertheless we are a part, became
completely separated from us, and was removed an
infinite distance away. Similarly, many a young man,
hearing for the first time of the refraction of stellar light,
has thought that doubt was cast on the whole of astronomy,
whereas nothing is required but an easily effected and
unimportant correction to put everything right again.
6.
We see an object having a point S. If we touch S,
that is, bring it into connexion with our body, we receive
a prick. We can see S, without feeling the prick. But
as soon as we feel the prick we find S on the skin. The
visible point, therefore, is a permanent nucleus, to which
the prick is annexed, according to circumstances, as some-
thing accidental. From the frequency of analogous
occurrences we ultimately accustom ourselves to regard
all properties of bodies as "effects" proceeding from
permanent nuclei and conveyed to the ego through the
medium of the body; which effects we call sensations.
By this operation, however, these nuclei are deprived of
their entire sensory content, and converted into mere
mental symbols. The assertion, then, is correct that the
world consists only of our sensations. In which case we
have knowledge only of sensations, and the assumption
of the nuclei referred to, or of a reciprocal action between
them, from which sensations proceed, turns out to be quite
idle and superfluous. Such a view can only suit with a half-
hearted realism or a half-hearted philosophical criticism.
THE ANALYSIS OF SENSATIONS 13
Ordinarily the complex a j3 y ... AT Z .A/" ... is con-
trasted as ego with the complex ABC... At first only those
elements of A B C . . . that more strongly alter a [3 y . . .,
as a prick, a pain, are wont to be thought of as comprised
in the ego. Afterwards, however, through observations
of the kind just referred to, it appears that the right to
annex ABC. . . to the ego nowhere ceases. In con-
formity with this view the ego can be so extended as
ultimately to embrace the entire world. 1 The ego is not
sharply marked off, its limits are very indefinite and
arbitrarily displaceable. only by failing to observe this
fact, and by unconsciously narrowing those limits, while
at the same time we enlarge them, arise, in the conflict
of points of view, the metaphysical difficulties met with
in this connexion.
As soon as we have perceived that the supposed unities
"body" and "ego" are only makeshifts, designed for
provisional orientation and for definite practical ends (so
that we may take hold of bodies, protect ourselves against
pain, and so forth), we find ourselves obliged, in many
1 When I say that the table, the tree, and so forth, are my sensations,
the statement, as contrasted with the mode of representation of the
ordinary man, involves a real extension of my ego. on the emotional
side also such extensions occur, as in the case of the virtuoso, who
possesses as perfect a mastery of his instrument as he does of his own
body; or in the case of the skilful orator, on whom the eyes of the
audience are all converged, and who is controlling the thoughts of all ;
or in that of the able politician who is deftly guiding his party ; and so
on. In conditions of depression, on the other hand, such as nervous people
often endure, the ego contracts and shrinks. A wall seems to separate
it from the world.
14 THE ANALYSIS OF SENSATIONS
more advanced scientific investigations, to abandon them as
insufficient and inappropriate. The antithesis between ego
and world, between sensation (appearance) and thing, then
vanishes, and we have simply to deal with the connexion of
the elements a$y . . . A J? C . . . KL M . . ., of which
this antithesis was only a partially appropriate and imperfect
ｅxpression. This connexion is nothing more or less than
the combination of the above-mentioned elements with
other similar elements (time and space). Science has
simply to accept this connexion, and to get its bearings in
it, without at once wanting to explain its existence.
on a superficial examination the complex a /3 y . . .
appears to be made up of much more evanescent elements
than ABC... and K L M . . ., in which last the
elements seem to be connected with greater stability and in
a more permanent manner (being joined to solid nuclei as
it were). Although on closer inspection the elements of
all complexes prove to be homogeneous, yet even when this
has been recognized, the earlier notion of an antithesis of
body and spirit easily slips in again. The philosophical
spiritualist is often sensible of the difficulty of imparting the
needed solidity to his mind-created world of bodies ; the
materialist is at a loss when required to endow the world of
matter with sensation. The monistic point of view, which
reflexion has evolved, is easily clouded by our older and
more powerful instinctive notions.
8.
The difficulty referred to is particularly felt when we
consider the following case. In the complex ABC. . .,
THE ANALYSIS OF SENSATIONS 15
which we have called the world of matter, we find as parts,
not only our own body K L M . . ., but also the bodies of
other persons (or animals) K' L' M' . . ., K" L' M" . . .,
to which, by analogy, we imagine other a' $' y' . . .,
a" (3" y" . . ., annexed, similar to a /3 y . . . So long as
we deal with K r Z' M' . . ., we find ourselves in a thor-
oughly familiar province which is at every point accessible^
to our senses. When, however, we inquire after the sensa- \
tions or feelings belonging to the body K' U M' . . ., we
no longer find these in the province of sense : we add them
in thought. Not only is the domain which we now enter
far less familiar to us, but the transition into it is also
relatively unsafe. We have the feeling as if we were plung-
ing into an abyss. 1 Persons who adopt this way of thinking
only, will never thoroughly rid themselves of that sense of
insecurity, which is a very fertile source of illusory problems.
But we are not restricted to this course. Let us consider,
first, the reciprocal relations of the elements of the complex
ABC. . ., without regarding K L M . . . (our body).
1 When I first came to Vienna from the country, as a boy of four or
five years, and was taken by my father upon the walls of the city's
fortifications, I was very much surprised to see people below in the
moat, and could not understand how, from my point of view, they
could have got there ; for the thought of another way of descent never
occurred to me. I remarked the same astonishment, once afterwards,
in the case of a three-year-old boy of my own, while walking on the walls
of Prague. I recall this feeling every time I occupy myself with the
reflexion of the text, and I frankly confess that this accidental experi-
ence of mine helped to confirm my opinion upon this point, which I
have now long held. Our habit of always following the same path,
whether materially or psychically, tends greatly to confuse our field of
survey. A child, on the piercing of the wall of a house in which he
has long dwelt, may experience a veritable enlargement of his world-
view, and in the same manner a slight scientific hint may often afford
great enlightenment.
16 THE ANALYSIS OF SENSATIONS
All physical investigations are of this sort. A white ball
falls upon a bell ; a sound is heard. The ball turns yellow
before a sodium lamp, red before a lithium lamp. Here
the elements (ABC. . . ) appear to be connected only
with one another and to be independent of our body
(K L M . . . ). But if we take santonine, the ball again
turns yellow. If we press one eye to the side, we see two
balls. If we close our eyes entirely, there is no ball there
at all. If we sever the auditory nerve, no sound is heard.
The elements ABC.. ., therefore, are not only con-
nected with one another, but also with K L M. To this
extent, and to this extent only> do we call ABC,.,
sensations^ and regard A B C as belonging to the ego. In
what follows, wherever the reader finds the terms " Sensa-
tion," " Sensation-complex," used alongside of or instead of
the ｅxpressions " element," " complex of elements," it must
be borne in mind that it is only in the connexion and
relation in question, only in their functional dependence,
that the elements are sensations. In another functional
relation they are at the same time physical objects. We
only use the additional term "sensations" to describe the
elements, because most people are much more familiar
with the elements in question as sensations (colors, sounds,
pressures, spaces, times, etc.), while according to the
popular conception it is particles of mass that are con-
sidered as physical elements, to which the elements, in the
sense here used, are attached as "properties " or "effects." *
1 A treatment of this fundamental point, identical in essentials, but
cast in a form which will be perhaps more acceptable to scientists, will
be found in my Erkenntnis und Irrtum, Leipzig, 1905 (2nd edition,
Leipzig, 1906.)
THE ANALYSIS OF SENSATIONS 17
In this way, accordingly, we do not find the gap between
bodies and sensations above described, between what is
without and what is within, between the material world and
the spiritual world. 1 All elements A B C . . ., K L M . . .,
constitute a single coherent mass only, in which, when any
one element is disturbed, all is put in motion ; except that
a disturbance in K L M . . . has a more extensive and
profound action than one in A B C ... A magnet in our
neighborhood disturbs the particles of iron near it; a
falling boulder shakes the earth \ but the severing of a nerve
sets in motion the whole system of elements.- Quite
involuntarily does this relation of things suggest the picture
of a viscous mass, at certain places (as in the ego) more
firmly coherent than in others. I have often made use of
this image in lectures.
Thus the great gulf between physical and psychological
research persists only when we acquiesce in our habitual
stereotyped conceptions. A color is a physical object as
soon as we consider its dependence, for instance, upon its
luminous source, upon other colors, upon temperatures,
upon spaces, and so forth. When we consider, however, its
dependence upon the retina (the elements KL M . . .),
it is a psychological object, a sensation. Not the subject-
1 Compare my Grundlinien der Lehre von den Bewegungsempfindim-
gen, Leipzig, Engelmann, 1875, p. 54. I there, for the first time,
stated my view shortly, but definitely, in these words : " Appearance
may be subdivided into elements, which, in so far as they are connected
with certain processes of our bodies, and can be regarded as conditioned
by these processes, we call sensations."
B
i8 THE ANALYSIS OF SENSATIONS
matter, but the direction of our investigation, is different in
the two domains. (Cp. also Chapter II., pp. 43, 44.)
Both in reasoning from the observation of the bodies
of other men or animals, to the sensations which they
possess, as well as in investigating the influence of our
own body upon our own sensations, we have to complete
observed facts by analogy. This is accomplished with
much greater ease and certainty, when it relates, say, only
to nervous processes, which cannot be fully observed in
our own bodies that is, when it is carried out in the more
familiar ..physical domain than when it is extended to
the psychical domain, to the sensations and thoughts of
other people. Otherwise there is no essential difference.
10.
The considerations just advanced, expressed as they have
been in an abstract form, will gain in strength and vividness
if we consider the concrete facts from which they flow.
Thus, I lie upon my sofa. . If I close my right eye, the
picture represented in the accompanying cut is presented
to my left eye. In a frame formed by the ridge of my
eyebrow, by my nose, and by my moustache, appears a
part of my body, so far as visible, with its environment. 1
My body differs from other human bodies beyond the
fact that every intense motor idea is immediately ex-
pressed by a movement of it, and that, if it is touched,
more striking changes are determined than if other bodies
1 A discussion of the binocular field of vision, with its peculiar
stereoscopic features, is omitted here, for although familiar to all, it is
not as easy to describe, and cannot be represented by a single plane
drawing.
THE ANALYSIS OF SENSATIONS 19
are touched by the circumstance, that it is only seen
piecemeal, and, especially, is seen without a head. If I
Fig. x.
observe an element A within my field of vision, and
investigate its connexion with another element B within
the same field, I step out of the domain of physics into
that of physiology or psychology, provided B, to use the
20 THE ANALYSIS OF SENSATIONS
apposite ｅxpression of a friend l of mine made upon seeing
this drawing, passes through my skin. Reflexions like
that for the field of vision may be made with regard to the
province of touch and the perceptual domains of the other
senses. 2
ii.
Reference has already been made to the different
character of the groups of elements denoted by A B C . . .
and a /3 y ... As a matter of fact, when we see a green
tree before us, or remember a green tree, that is, represent
a green tree to ourselves, we are perfectly aware of the
difference of the two cases. The represented tree has a
much less determinate, a much more changeable form ;
its green is much paler and more evanescent ; and, what
is of especial note, it plainly appears in a different domain.
A movement that we will to execute is never more than a
represented movement, and appears in a different domain
from that of the executed movement, which always takes
place when the image is vivid enough. Now the statement
1 J. Popper of Vienna.
2 It was about 1870 that the idea of this drawing was suggested to
me by an amusing chance. A certain Mr L., now long dead, whose
many eccentricities were redeemed by his truly amiable character,
compelled me to read one of C. F. Krause's writings, in which the
following occurs :
" Problem : To carry out the self-inspection of the Ego.
Solution : It is carried out immediately."
In order to illustrate in a humorous manner this philosophical " much
ado about nothing," and at the same time to shew how the self-
inspection of the Ego could be really "carried out," I embarked on the
above drawing. Mr L.'s society was most instructive and stimulating
to me, owing to the naivety with which he gave utterance to philo-
sophical notions that are apt to be carefully passed over in silence or
involved in obscurity.
THE ANALYSIS OF SENSATIONS 21
that the elements A and a appear in different domains,
means, if we go to the bottom of it, simply this, that these
elements are united with different other elements. Thus
far, therefore, the fundamental constituents of A B C . . .,
a (3 y . . . would seem to be the same (colors, sounds,
spaces, times, motor sensations . . .), and only the
character of their connexion different.
Ordinarily pleasure and pain are regarded as different
from sensations. Yet not only tactual sensations, but all
other kinds of sensations, may pass gradually into pleasure
and pain. Pleasure and pain also may be justly termed
sensations. only they are not so well analysed and so
familiar, nor, perhaps, limited to so few organs as the
common sensations. In fact, sensations of pleasure and
pain, however faint they may be, really constitute an
essential part of the content of all so-called emotions.
Any additional element that emerges into consciousness
when we are under the influence of emotions may be
described as more or less diffused and not sharply local-
ized sensations. William James, 1 and after him Theodule
Ribot, 2 have investigated the physiological mechanism of
the emotions : they hold that what is essential is purposive
tendencies of the body to action tendencies which cor-
respond to circumstances and are expressed in the organism.
only a part of these emerges into consciousness. We
are sad because we shed tears, and not vice versa^
says James. And Ribot justly observes that a cause of
the backward state of our knowledge of the emotions is
1 W. James, Psychology ', New York, 1890, II., p. 442.
2 Th. Ribot, La psychologic des sentiments, 1896. (English trans-
lation, The Psychology of 'the Emotions > 1897.)
22 THE ANALYSIS OF SENSATIONS
that we have always confined our observation to so much
of these physiological processes as emerges into conscious-
ness. At the same time he goes too far when he main-
tains that everything psychical is merely " surajoute" to
the physical, and that it is only the physical that produces
effects. For us this distinction is non-existent.
Thus, perceptions, presentations, volitions, and emotions,
in short the whole inner and outer world, are put together, in
combinations of varying evanescence and permanence, out
of a small number of homogeneous elements. Usually, these
elements are called sensations. But as vestiges of a one-
sided theory inhere in that term, we prefer to speak simply of
elements, as we have already done. The aim of all research
is to ascertain the mode of connexion of these elements. 1
If it proves impossible to solve the problem by assuming one
set of such elements, then more than one will have to be
assumed. But for the questions under discussion it would be
improper to begin by making complicated assumptions in
advarice.
12.
That in this complex of elements, which fundamentally
is only one, the boundaries of bodies and of the ego do
not admit of being established in a manner definite and
sufficient for all cases, has already been remarked. To
bring together elements that are most intimately connected
with pleasure and pain into one ideal mental-economical
1 Compare the note at the conclusion of my treatise, Die Geschichte
^lnd die Wurzel des Satzes der Erhaltung der Arbeit, Prague, Calve,
1 872. {History and Root of the Principle, of the Conservation of Energy.
Translated and annotated by P. E. B. Jourdain, Chicago, Open Court
Publishing Co., 1911.)
THE ANALYSIS OF SENSATIONS 23
unity, the ego ; this is a task of the highest importance
for the intellect working in the service of the pain-avoiding,
pleasure-seeking will. The delimitation of the ego, there-
fore, is instinctively effected, is rendered familiar, and
possibly becomes fixed through heredity. Owing to their
high practical importance, not only for the individual, but
for the entire species, the composites " ego " and " body "
instinctively make good their claims, and assert themselves
with elementary force. In special cases, however, in which
practical ends are not concerned, but where knowledge
is an end in itself, the delimitation in question may prove
to be insufficient, obstructive, and untenable. 1
The primary fact is not the ego, but the elements
(sensations). What was said on p. 21 as to the term
" sensation " must be borne in mind. The elements
constitute the I. 7 have the sensation green, signifies
that the element green occurs in a given complex of other
elements (sensations, memories). When 7 cease to have
the sensation green, when 7 die, then the elements no
1 Similarly, class-consciousness, class-prejudice, the feeling of nation-
ality, and even the narrowest-minded local patriotism may have a high
importance, jor certain purposes. But such attitudes will not be
shared by the broad-minded investigator, at least not in moments of
research. All such egoistic views are adequate only for practical
purposes. Of course, even the investigator may succumb to habit.
Trifling pedantries and nonsensical discussions ; the cunning appro-
priation of others' thoughts, with perfidious silence as to the sources ;
when the word of recognition must be given, the difficulty of swallow-
ing one's defeat, and the too common eagerness at the same time to set
the opponent's achievement in a false light : all this abundantly shows
that the scientist and scholar have also the battle of existence to fight,
that the ways even of science still lead to the mouth, and that the
pure impulse towards knowledge is still an ideal in our present social
conditions.
24 THE ANALYSIS OF SENSATIONS
longer occur in the ordinary, familiar association. That
is all. only an ideal mental-economical unity, not a real
unity, has ceased to exist. The ego is not a definite,
unalterable, sharply - bounded unity. None of these
attributes are important ; for all vary even within the
sphere of individual life; in fact their alteration is even
sought after by the individual. Continuity alone is
important. This view accords admirably with the position
which Weismann has reached by biological investigations.
(" Zur Frage der Unsterblichkeit der Einzelligen," Biolog.
Centralbl.^ Vol. IV., Nos. 21, 22 ; compare especially
pages 654 and 655, where the scission of the individual
into two equal halves is spoken of.) But continuity is
only a means of preparing and conserving what is con-
tained in the ego. This content, and not the ego, is the
principal thing. This content, however, is not confined
to the individual. With the exception of some insignificant
and valueless personal memories, it remains preserved in
others even after the death of the individual. The elements
that make up the consciousness of a given individual are
firmly connected with one another, but with those of
another individual they are only feebly connected, and
the connexion is only casually apparent. Contents of
consciousness, however, that are of universal significance,
break through these limits of the individual, and, attached
of course to individuals again, can enjoy a continued exist-
ence of an impersonal, superpersonal kind, independently
of the personality by means of which they were developed.
To contribute to this is the greatest happiness of the artist,
the scientist, the inventor, the social reformer, etc.
The ego must be given up. It is partly the perception
THE ANALYSIS OF SENSATIONS 25
of this fact, partly the fear of it, that has given rise to the
many extravagances of pessimism and optimism, and to
numerous religious, ascetic, and philosophical absurdities.
In the long run we shall not be able to close our eyes to
this simple truth, which is the immediate outcome of
psychological analysis. We shall then no longer place so
high a value upon the ego, which even during the in-
dividual life greatly changes, and which, in sleep or during
absorption in some idea, just in our very happiest
moments, may be partially or wholly absent. We shall
then be willing to renounce individual immortality, 1 and
not place more value upon the subsidiary elements than
upon the principal ones. In this way we shall arrive at
a freer and more enlightened view of life, which will
preclude the disregard of other egos and the over-
estimation of our own. The ethical ideal founded on
this view of life will be equally far removed from the
ideal of the ascetic, which is not biologically tenable for
whoever practises it, and vanishes at once with his dis-
appearance, and from the ideal of an overweening
Nietzschean "superman," who cannot, and I hope will
not be tolerated by his fellow-men. 2
If a knowledge of the connexion of the elements (sensa-
tions) does not suffice us, and we ask, Who possesses this
connexion of sensations, Who experiences it? then we
have succumbed to the old habit of subsuming every
1 In wishing to preserve our personal memories beyond death, we
are behaving like the astute Eskimo, who refused with thanks the gift
of immortality without his seals and walruses.
2 However far the distance is from theoretical understanding to
practical conduct, still the latter cannot in the long run resist the
former.
26 THE ANALYSIS OF SENSATIONS
element (every sensation) under some unanalysed complex,
and we are falling back imperceptibly upon an older,
lower, and more limited point of view. It is often pointed
out, that a psychical experience which is not the experience
of a determinate subject is unthinkable, and it is held that
in this way the essential part played by the unity of con-
sciousness has been demonstrated. But the Ego-conscious-
ness can be of many different degrees and composed of a
multiplicity of chance memories. one might just as well
say that a physical process which does not take place in
some environment or other, or at least somewhere in the
universe, is unthinkable. In both cases, in order to make
a beginning with our investigation, we must be allowed to
abstract from the environment, which, as regards its influ-
ence, may be very different in different cases, and in special
cases may shrink to a minimum. Consider the sensations
of the lower animals, to which a subject with definite
features can hardly be ascribed. It is out of sensations
that the subject is built up, and, once built up, no doubt
the subject reacts in turn on the sensations.
The habit of treating the unanalysed ego complex as an
indiscernible unity frequently assumes in science remark-
able forms. First, the nervous system is separated from
the body as the seat of the sensations. In the nervous
system again, the brain is selected as the organ best fitted
for this end, and finally, to save the supposed psychical
unity, a point is sought in the brain as the seat of the soul.
But such crude conceptions are hardly fit even to fore-
shadow the roughest outlines of what future research will
do for the connexion of the physical and the psychical.
The fact that the different organs and parts of the nervous
THE ANALYSIS OF SENSATIONS 27
system are physically connected with, and can be readily
excited by, one another, is probably at the bottom of the
notion of " psychical unity."
I once heard the question seriously discussed, "How
the perception of a large tree could find room in the little
head of a man?" Now, although this "problem" is no
problem, yet it renders us vividly sensible of the absurdity
that can be committed by thinking sensations spatially into
the brain. When I speak of the sensations of another
person, those sensations are, of course, not exhibited in
my optical or physical space ; they are mentally added, and
I conceive them causally, not spatially, attached to the
brain observed, or rather, functionally presented. When I
speak of my own sensations, these sensations do not exist
spatially in my head, but rather my "head" shares with
them the same spatial field, as was explained above.
(Compare the remarks on Fig. i on pp. 17-19 above.) 1
The unity of consciousness is not an argument in point.
1 As early as the writings of Johannes Miiller, we can already find a
tendency towards views of this kind, although his metaphysical bias
prevents him from carrying them to their logical conclusion. But
Hering (Hermann's Handb^tch der Physiologic, Vol. III., p. 345) has
the following characteristic passage: "The material of which visual
objects consists is the visual sensations. The setting sun, as a visual
object, is a flat, circular disk, which consists of yellowish-red color,
that is to say of a visual sensation. We may therefore describe it
directly as a circular, yellowish-red sensation. This sensation we have
in the very place where the sun appears to us." I must confess that, so
far as the experiments go which I have had occasion to make in con-
versation, most people, who have not come to close quarters with
these questions by serious thinking, will pronounce this way of looking
at the matter to be mere hair-splitting. Of course, what is chiefly
responsible for their indignation is the common confusion between
sensible and conceptual space. But anyone who takes his stand as I
do on the economic function of science, according to which nothing is
28 THE ANALYSIS OF SENSATIONS
Since the apparent antithesis between the real world and
the world given through the senses lies entirely in our
mode of view, and no actual gulf exists between them, a
complicated and variously interconnected content of con-
sciousness is no more difficult to understand than is the
complicated interconnexion of the world.
If we regard the ego as a real unity, we become involved
in the following dilemma : either we must set over against
the ego a world of unknowable entities (which would be
quite idle and purposeless), or we must regard the whole
world, the egos of other people included, as comprised in
our own ego (a proposition to which it is difficult to yield
serious assent).
But if we take the ego simply as a practical unity, put
together for purposes of provisional survey, or as a more
strongly^cohering group of elements, less strongly connected
with other groups of this kind, questions like those above
discussed will not arise, and research will have an unob-
structed future.
In his philosophical notes Lichtenberg says : " We
important except what can be observed or is a datum for us, and
everything hypothetical, metaphysical and superfluous, is to be
eliminated, must reach the same conclusion. I think that a similar
standpoint is to be ascribed to Avenarius, for in his Der menschliche
Weltbegriff, p. 76, the following passages occur: "The brain is not
the dwelling-place, seat or producer of thought ; it is not the instru-
ment or organ, it is not the vehicle or substratum, etc., of thought."
"Thought is not an indweller or command-giver, it is not a second
half or aspect, etc., nor is it a product; it is not even a physiological
function of the brain, nor is it a state of the brain at all. " I am not
able or willing to subscribe to all that Avenarius says or to any inter-
pretation of what he says, but still his conception seems to me to
approximate very nearly to my own. The method which he terms,
"The exclusion of introjection," is only a particular form of the
elimination of the metaphysical.
THE ANALYSIS OF SENSATIONS 29
become conscious of certain presentations that are not
dependent upon us ; of others that we at least think
are dependent upon us. Where is the border-line? We
know only the existence of our sensations, presentations,
and thoughts. We should say, // thinks, just as we
say, // lightens. It is going too far to say cogito, if we
translate cogito by / think. The assumption, or postula-
tion, of the ego is a mere practical necessity." Though the
method by which Lichtenberg arrived at this result is some-
what different from ours, we must nevertheless give our full
assent to his conclusion.
Bodies do not produce sensations, but complexes
of elements (complexes of sensations) make up bodies.
If, to the physicist, bodies appear the real, abiding
existences, whilst the " elements " are regarded merely as
their evanescent, transitory appearance, the physicist for-
gets, in the assumption cf such a view, that all bodies are
but thought-symbols for complexes of elements (complexes
of sensations). Here, too, the elements in question form
the real, immediate, and ultimate foundation, which it is
the task of physiologico-physical research to investigate.
By the recognition of this fact, many points of physiology
and physics assume more distinct and more economical
forms, and many spurious problems are disposed of.
For us, therefore, the world does not consist of
mysterious entities, which by their interaction with
another, equally mysterious entity, the ego, produce
sensations, which alone are accessible. For us, colors,
sounds, spaces, times, . . . are provisionally the ultimate
3 o THE ANALYSIS OF SENSATIONS
elements, whose given connexion it is our business to
investigate. 1 It is precisely in this that the exploration of
1 I have always felt it as a stroke of special good fortune, that early in
life, at about the age of fifteen, I lighted, in the library of my father, on
a copy of Kant's Prolegomena to any Future Metaphysics. The book
made at the time a powerful and ineffaceable impression upon me, the
like of which I never afterwards experienced in any of my philosophical
reading. Some two or three years later the superfluity of the r61e
played by "the thing in itself" abruptly dawned upon me. on a
bright summer day in the open air, the world with my ego suddenly
appeared to me as one coherent mass of sensations, only more strongly
coherent in the ego. Although the actual working out of this thought
did not occur until a later period, yet this moment was decisive for my
whole view. I had still to struggle long and hard before I was able to
retain the new conception in my special subject. With the valuable
parts of physical theories we necessarily absorb a good dose of false
metaphysics, which it is very difficult to sift out from what deserves to
be preserved, especially when those theories have become very familiar
to us. At times, too, the traditional, instinctive views would arise
with great power and place impediments in my way. only by alternate
studies in physics and in the physiology of the senses, and by historico-
physical investigations (since about 1863), and after having endeavored
in vain to settle the conflict by a physico-psychological monadology
(in my lectures on psycho-physics, in the Zeitschrift fiir praktische
Heilkunde, Vienna, 1863, p. 364), have I attained to any considerable
stability in my views. I make no pretensions to the title of philosopher.
I only seek to adopt in physics a point of view that need not be changed
the moment our glance is carried over into the domain of another
science ; for, ultimately, all must form one whole. The molecular
physics of to-day certainly does not meet this requirement. What I
say I have probably not been the first to say. I also do not wish to
offer this exposition of mine as a special achievement. It is rather my
belief that every one will be led to a similar view, who makes a
careful survey of any extensive body of knowledge. Avenarius, with
whose works I became acquainted in 1883, approaches my point of view
(Philosophic als Denken der Welt nach dem Princip des kleinsten Kraft-
masses^ 1876). Also Hering, in his paper on Memory {Almanack der
Wiener Akademie, 1870, p. 258 ; English translation, O. C. Pub. Co.,
Chicago, 4th edition, enlarged, 1913), and J. Popper in his beautiful
book, Das Rchte zu leben und die Pflicht zu sterben (Leipzig, 1878, p.
62), have advanced allied thoughts. Compare also my paper Ueber
THE ANALYSIS OF SENSATIONS 31
reality consists. In this investigation we must not allow
ourselves to be impeded by such abridgments and
delimitations as body, ego, matter, spirit, etc., which have
been formed for special, practical purposes and with
wholly provisional and limited ends in view. on the
contrary, the fittest forms of thought must be created in and
by that research itself, just as is done in every special science.
In place of the traditional, instinctive ways oif,4<hought, a
freer, fresher view, conforming to developed experience, and
reaching out beyond the requirements of practical life, must
be substituted throughout.
14.
Science always has its origin in the adaptation of thought to
some definite field of experience. The results of the adapta-
tion are thought-elements, which are able to represent the
whole field. The outcome, of course, is different, according
to the character and extent of the field. If the field of
experience is enlarged, or if several fields heretofore discon-
nected are united, the traditional, familiar thought-elements
no longer suffice for the extended field. In the struggle of
acquired habit with the effort after adaptation, problems
arise, which disappear when the adaptation is perfected, to
make room for others which have arisen meanwhile.
die okonomische Natur der physikalischen Forschung {Almanack der
Wiener A kademie, 1882, p. 179, note ; English translation in my Popular
Scientific Lectures, Chicago, 1894). Finally let me also refer here to
the introduction to W. Preyer's Reine Empfindungshhre, to Riehl's
Freiburger Antrittsrede, p. 40, and to R. Wahle's Gehirn und
Bewusstsein, 1884. My views were indicated briefly in 1872 and 1875,
and not expounded at length until 1882 and 1883. I should probably
have much additional matter to cite as more or less allied to this line
of thought, if my knowledge of the literature were more extensive.
32 THE ANALYSIS OF SENSATIONS
To the physicist, qua physicist, the idea of "body" is
productive of a real facilitation of view, and is not the
cause of disturbance. So, also, the person with purely
practical aims, is materially supported by the idea of the
/ or ego. For, unquestionably, every form of thought that
has been designedly or undesignedly constructed for a
given purpose, possesses for that purpose a permanent
value. When, however, physics and psychology meet, the
ideas held in the one domain prove to be untenable in the
other. From the attempt at mutual adaptation arise the
various atomic and monadistic theories which, however,
never attain their end. If we regard sensations, in the
sense above defined (p. 13), as the elements of the world,
the problems referred to appear to be disposed of in all
essentials, and the first and most important adaptation to
be consequently effected. This fundamental view (without
any pretension to being a philosophy for all eternity) can
at present be adhered to in all fields of experience ; it is
consequently the one that accommodates itself with the
least expenditure of energy, that is, more economically
than any other, to the present temporary collective state
of knowledge Furthermore, in the consciousness of its
purely economical function, this fundamental view is
eminently tolerant. It does not obtrude itself into fields
in which the current conceptions are still adequate. It
is also ever ready, upon subsequent extensions of the
field of experience, to give way before a better con-
ception.
The presentations and conceptions of the average man
of the world are formed and dominated, not by the full
and pure desire for knowledge as an end in itself, but by
THE ANALYSIS OF SENSATIONS 33
the struggle to adapt himself favourably to the conditions
of life. Consequently they are less exact, but at the same
time also they are preserved from the monstrosities which
easily result from a one-sided and impassioned pursuit
of a scientific or philosophical point of view. The unpre-
judiced man of normal psychological development takes the
elements which we have called A B C . . . to be spatially
contiguous and external to the elements K L M . . .,
and he holds this view immediately ', and not by any process
of psychological projection or logical inference or construc-
tion ; even were such a process to exist, he would certainly
not be conscious of it. He sees, then, an "external
world "ABC... different from his body K L M . . .
and existing outside it. As he does not observe at first
the dependence of the A B Cs . . . on the K L M's . . .
(which are always repeating themselves in the same way
and consequently receive little attention), but is always
dwelling upon the fixed connexion of the A B Cs . . .
with one another, there appears to him a world of things
independent of his Ego. This Ego is formed by the
observation of the special properties of the particular thing
K L M . . . with which pain, pleasure, feeling, will, etc.,
are intimately connected. Further, he notices things
K' L' M', K" L" M", which behave in a manner perfectly
analogous to K L M, and whose behaviour he thoroughly
understands as soon as he has thought of analogous feel-
ings, sensations, etc., as attached to them in the same way
as he observed these feelings, sensations, etc., to be
attached to himself. The analogy impelling him to this
result is the same as determines him, when he has
observed that a wire possesses all the properties of a
34 THE ANALYSIS OF SENSATIONS
conductor charged with an electric current, except one
which has not yet been directly demonstrated, to conclude
that the wire possesses this one property as well. Thus,
since he does not perceive the sensations of his fellow-
men or of animals but only supplies them by analogy,
while he infers from the behaviour of his fellow-men that
they are in the same position over against himself, he is
led to ascribe to the sensations, memories, etc., a particular
ABC...KLM...viz. different nature, always
differently conceived according to the degree of civilization
he has reached ; but this process, as was shown above, is un-
necessary, and in science leads into a maze of error, although
the falsification is of small significance for practical life.
These factors, determining as they do the intellectual
outlook of the plain man, make their appearance alter-
nately in him according to the requirements of practical
life for the time being, and persist in a state of nearly
stable equilibrium. The scientific conception of the world,
however, puts the emphasis now upon one, now upon the
other factor, makes sometimes one and sometimes the
other its starting-point, and, in its struggle for greater pre-
cision, unity and consistency, tries, so far as seems possible,
to thrust into the background all but the most indispensable
conceptions. In this way dualistic and monistic systems arise.
The plain man is familiar with blindness and deafness,
and knows from his everyday experience that the look of
things is influenced by his senses ; but it never occurs to
him to regard the whole world as the creation of his senses.
He would find an idealistic system, or such a monstrosity as
solipsism, intolerable in practice.
It may easily become a disturbing element in unpre-
THE ANALYSIS OF SENSATIONS
35
judiced scientific theorizing when a conception which is
adapted to a particular and strictly limited purpose is
promoted in advance to be the foundation of all investiga-
tion. This happens, for example, when all experiences are
regarded as " effects " of an external world extending into
consciousness. This conception gives us a tangle of meta-
physical difficulties which it seems impossible to unravel.
But the spectre vanishes at once when we look at the
matter as it were in a mathematical light, and make it clear
to ourselves that all that is valuable to us is the' discovery
of functional relations^ and that what we want to know is
merely the dependence of experiences on one another. It
then becomes obvious that the reference to unknown funda-
mental variables which are not given (things-in-themselves)
is purely fictitious and superfluous. But even when we
allow this fiction, uneconomical though it be, to stand at
first, we can still easily distinguish different classes of the
mutual dependence of the elements of " the facts of con-
sciousness " ; and this alone is important for us.
ABC . . . . KLM . . .
a/3 7 . . .
K' L' M' . . .
a'/3' 7 ' . .
K" L" M" . . .
a" /3V
The system of the elements is indicated in the above
scheme. Within the space surrounded by a single line lie
the elements which belong to the sensible world, the
elements whose regular connexion and peculiar dependence
on one another represent both physical (lifeless) bodies and
the bodies of men, animals and plants. All these elements,
again, stand in a relation of quite peculiar dependence to
36 THE ANALYSIS OF SENSATIONS
certain of the elements K L M the nerves of our body,
namely by which the facts of sense-physiology are
expressed. The space surrounded by a double line con-
tains the elements belonging to the higher psychic life,
memory-images and presentations, including those which
we form of the psychic life of our fellow-men. These may
be distinguished by accents. These presentations, again,
are connected with one another in a different way (associa-
tion, fancy) from the sensational elements A B C . .'.
K L M, but it cannot be doubted that they are very closely
allied to the latter, and that in the last resort their behaviour
is determined by A B C . . . K L M (the totality of the
physical world), and especially by our body and nervous
system. The presentations a! (3 f y r of the contents of the
consciousness of our fellow-men play for us the part of
intermediate substitutions, by means of which the behaviour
of our fellow-men, the functional relation of K' L' M' to
A B C becomes intelligible, in so far as in and for itself
(physically) it would remain unexplained.
It is therefore important for us to recognize that in all
questions in this connexion, which can be intelligibly asked
and which can interest us, everything turns on taking into
consideration different ultimate variables and different
relations of dependence. That is the main point. Nothing
will be changed in the actual facts or in the functional
relations, whether we regard all the data as contents of con-
sciousness, or as partially so, or as completely physical. 1
1 Cf. J. Petzoldt's excellent paper " Solipsismus auf praktischem
Gebiet" ( Vierteljahrsschriftfiirwissentschaftliche Philosophic, XXXV. ,
3> P- 339) Schuppe, " Der Solipsismus" (Zeitschr fUr immanente
Philosophie, Vol. III., p. 327).
J
THE ANALYSIS OF SENSATIONS 37
The biological task of science is to provide the fully
developed human individual with as perfect a. means of
orientating himself as possible. No other scientific ideal
can be realized, and any other must be meaningless.
The philosophical point of view of the average man if
that term may be applied to his naive realism has a claim
to the highest consideration. It has arisen in the process of
immeasurable time without the intentional assistance of man.
It is a product of nature, and is preserved by nature. Every-
thing that philosophy has accomplished though we may
admit the biological justification of every advance, nay, of
every error is, as compared with it, but an insignificant
and ephemeral product of art. The fact is, every thinker,
every philosopher, the moment he is forced to abandon his
one-sided intellectual occupation by practical necessity,
immediately returns to the general point of view of man-
kind. Professor X., who theoretically believes himself to
be a solipsist, is certainly not one in practice when he has
to thank a Minister of State for a decoration conferred upon
him, or when he lectures to an audience. The Pyrrhonist
who is cudgelled in Moliere's Le Manage Forc'e^ does not go
on saying " II me semble que vous me battez," but takes
his beating as really received.
Nor is it the purpose of these " introductory remarks " to
discredit the standpoint of the plain man. The task which
we have set ourselves is simply to show why and for what
purpose we hold that standpoint during most of our lives,
and why and for what purpose we are provisionally obliged
to abandon it. No point of view has absolute, permanent
validity. Each has importance only for some given end.
II. on PRECONCEIVED OPINIONS
i.
THE physicist has frequent occasion to observe how
greatly our knowledge of some field of research may
be hampered, when, instead of the unprejudiced investiga-
tion of that field for its own sake, views are transferred to it
which have been formed in some other department of
knowledge. Far more serious is the confusion which arises
from such transference of preconceived opinions from the
field of physics to that of psychology. Let us illustrate this
by a few examples.
A physicist observes the inverted image on the retina of
an excised eye, and puts to himself very naturally the
question, How does a point situated low down in space
come to be reflected on the upper part of the retina ? He
answers this question by the aid of studies in dioptrics. If,
now, this question, which is perfectly legitimate in the
province of physics, be transferred to the domain of
psychology, only obscurity will be produced. The question
why we see inverted retinal images the right way up, has no
meaning as a psychological problem. The light-sensations
of the separate spots of the retina are connected with space-
sensations from the very outset, and we give the name
" above " to those positions in space that correspond to the
parts of the retina situated lower down. To the subject
having the sensation such a question cannot present itself.
38
THE ANALYSIS OF SENSATIONS 39
It is the same with the well-known theory of external
projection. The problem of the physicist is, to find the
luminous object-point corresponding to a point on the
retinal image, by prolonging the ray that passes through the
point on the image and the centre of the eye. For the
subject having the sensation this problem does not exist, as
the light sensations are connected from the beginning with
determinate space-sensations. The entire theory of the
psychological origin of the external world by the projection
of sensations outwards is founded solely on a mistaken
application of physical points of view. Our sensations of
sight and touch are bound up with various different sensa-
tions of space ; that is to say, they exist by the side of one
another and outside one another, exist, in other words, in a
spatial field, in which our body fills but a part. The table,
the house, the tree, lie thus self-evidently outside my body.
A projection-problem never presents itself, is neither
consciously nor unconsciously solved.
A physicist (Mariotte) discovers that a certain spot on
the retina is blind. The physicist is accustomed to
correlate with every spatial point a point on the retinal
image, and with every point on the image a sensation.
Hence the question arises, What do we see at the points
corresponding to the blind spot, and how is the gap filled
out ? When the illegitimate form of putting the question in
physical terms is eliminated from the psychological inquiry,
it will be found that no problem exists at all here. We see
nothing at the blind spots, the gap in the image is not filled
out, or rather, the gap is not felt, for the simple reason that
a defect of light-sensation can no more be noticed at a spot
blind from the beginning than the blindness, say, of
40 THE ANALYSIS OF SENSATIONS
the skin of the back can cause a gap in the visual
field.
I have intentionally chosen simple and obvious examples,
as they can best make clear what unnecessary confusion is
caused by the thoughtless transference of a conception or
mode of thought, which is valid and serviceable in one field,
into another quite different field.
In the work of a celebrated German ethnographer I
recently read the following sentence : " This tribe has
become deeply degraded through the practice of canni-
balism." By its side lay the book of an English inquirer
who deals with the same subject. The latter simply puts
the question why certain South-Sea Islanders are cannibals,
finds out in the course of his inquiries that our own
ancestors also were once cannibals, and comes to under-
stand the position the Hindus take in the matter a point
of view that occurred once to my five-year-old boy who
while eating a piece of meat stopped, suddenly shocked,
and cried out, " We are cannibals to the animals ! "
" Thou shalt not eat human beings " is a very praiseworthy
maxim ; but in the mouth of the ethnographer it destroys
that mild and sublime glow of freedom from prepossession
by which we delight to recognize the true inquirer. But a
step further, and we shall say, " Man must not be descended
from monkeys," <k The earth ought not to rotate," "Matter
ought not to fill space continuously," " Energy must be
constant," and so on. I believe that our procedure differs
from that just characterized only in degree and not in kind,
when we claim absolute validity for views reached in the
field of physics, and transfer them to the field of psychology
without having first tested their applicability. In such cases
THE ANALYSIS OF SENSATIONS 41
we succumb to dogma, if not, like our scholastic forefathers,
to dogma forced upon us from without, yet to that which
we have created ourselves. And what result of research is
there that could not become a dogma by long habit ? The
very skill which we have acquired to deal with constantly
recurring intellectual situations deprives us of the freshness
and open-mindedness which we so greatly need in new
situations.
After these general remarks, I may perhaps be able
to explain my position with regard to the dualism of the
physical and the psychical. This dualism is to my mind
artificial and unnecessary.
In the investigation of purely physical processes we
generally employ concepts of so abstract a character
that as a rule we think only cursorily, or not at all,
of the sensations (elements) that lie at their base. For
example, when I ascertain the fact that an electric current
having the intensity of i ampere develops icj cubic
centimetres of oxyhydrogen gas at o C. and 760 mm.
mercury-pressure in a minute, I am readily disposed to
attribute to the objects defined a reality wholly inde-
pendent of my sensations. But I am obliged, in order
to arrive at what I have defined, to conduct the current,
for the existence of which my sensations are my only
warrant, through a circular wire having a definite radius,
so that the current, the intensity of terrestrial magnetism
being given, shall turn the magnetic needle a certain
angular distance out of the meridian. The determina-
tion of the magnetic intensity, of the volume of the
42 THE ANALYSIS OF SENSATIONS
oxyhydrogen gas, etc., is no less intricate. The whole
statement is based upon an almost unending series of
sensations, particularly if we take into consideration the
adjustment of the apparatus, which must precede the
actual experiment. Now it can easily happen to the
physicist who does not study the psychology of his
operations, that he does not (to reverse a well-known
saying) see the trees for the wood, that he overlooks
the sensory elements at the foundation of his work.
Now I maintain that every physical concept means
nothing but a certain definite kind of connexion of the
sensory elements which I have denoted by A B C. . . .
These elements elements in the sense that no further
resolution has as yet been made of them are the
simplest materials out of which the physical, and also
the psychological, world is built up.
Physiological research also may be of a purely physical
character. I can follow the course of a physical process
as it propagates itself through a sensitive nerve to the
central organ ; I can thence trace it by various paths to
the muscles, whose contraction produces new physical
changes in the environment. In so doing I am precluded
from thinking of any sensation felt by the man or animal
under observation ; what I am investigating is a purely
physical object. Very much is lacking, it is true, to our
complete comprehension of the details of this process,
and the assurance that everything depends on "the
motion of molecules " can neither console me nor deceive
me with respect to my ignorance.
Long prior to the development of a scientific psychology
people had nevertheless perceived that the behaviour of
THE ANALYSIS OF SENSATIONS 43
an animal under physical influences can be predicted
with much greater accuracy, i.e., can be better under-
stood, if we attribute to the animal sensations and
memories like our own. To that which I observe, to my
sensations, I have to supply mentally the sensations of
the animal, which are not to be found in the field of
my own sensations. This antithesis appears even more
abrupt to the scientific inquirer who is investigating a
nervous process by the aid of colorless abstract concepts,
and is required, for example, to add mentally to that
process the sensation green. This last may actually
appear as something entirely new and strange, and we
ask ourselves how it is that this miraculous thing is
produced from chemical processes, electrical currents,
and the like.
Psychological analysis has taught us that this surprise
is unjustifiable, since the physicist is always operating
with sensations. The same analysis also shows us that
the process of mentally supplementing complexes of
sensations according to analogy by means of elements
which at the moment are not being observed, or by
elements which cannot possibly be observed, is one
which is daily practised by the physicist ; as, for example,
when he imagines the moon a tangible, inert, heavy
mass. The totally strange character of the intellectual
situation above described is therefore an illusion.
There is also another consideration, a consideration
confined to my own sensory sphere, which serves to
dispel the illusion. Before me lies the leaf of a plant.
44 THE ANALYSIS OF SENSATIONS
The green (A) of the leaf is connected with a certain
optical sensation of space (B)> with a sensation of touch
(C), and with the visibility of the sun or the lamp (Z>).
If the yellow (JE) of a sodium flame takes the place of
the sun, the green (A) will pass into brown (F). If the
chlorophyl granules be removed by alcohol, an operation
which can be represented, like the preceding one, by
elements, the green (A) will pass into white (G). All
these observations are physical observations. But the
green (A) is also connected with a certain process of my
retina. There is nothing to prevent me in principle from
investigating this process in my own eye in exactly the
same manner as in the previous cases, and from reducing
it to its elements X Y Z . . . If there are difficulties in
doing this for my own eye, it can be done with some one
else's eye, and the gap filled out by analogy, exactly as in
other physical investigations. Now in its dependence
upon BCD. . . ., A is a physical element, in its depend-
ence on X Y Z . . . it is a sensation, and can also be
considered as a psychical element. The green (A),
however, is not altered at all in itself, whether we direct
our attention to the one or to the other form of depend-
ence. I see, therefore, no opposition of physical and
psychical, but simple identity as regards these elements.
In the sensory sphere of my consciousness everything is
at once physical and psychical (cp. p. 17).
4-
The obscurity of this intellectual situation has, I take it,
arisen solely from the transference of a physical preposses-
THE ANALYSIS OF SENSATIONS 45
sion to the field of psychology. The physicist says : I
find everywhere bodies and the motions of bodies only,
no sensations ; sensations, therefore, must be something
entirely different from the physical objects I deal with.
The psychologist accepts the second portion of this
declaration. For him, as is proper, sensations are the
primary data ; but to these there corresponds a mysterious
physical something which, conformably with the pre-
possession, must be quite different from sensations. But
what is it that is the really mysterious thing ? Is it the
Physis or the Psyche ? Or is it perhaps both ? It would
almost appear so, as it is now the one and now the other
that appears unattainable and involved in impenetrable
obscurity. Or are we here being led round in a circle by
some evil spirit ? >
I believe that the latter is the case. For me the
elements A B C ... are immediately and indubitably
given, and for me they can never afterwards be volatilized
away by considerations which ultimately are always based
on their existence.
The task of specialized investigation in the sensory
physico-psychical sphere, which has not been made
superfluous by this general survey, is to ascertain the
peculiar method of combination of the A B C s. This
may be expressed symbolically by saying that it is the
object of special research to find equations of the form
f(AB C . . .) = o(zero).
III. MY RELATION TO RICHARD
AVENARIUS AND OTHER
THINKERS.
i.
I HAVE already alluded to points at which the views
here advocated are in touch with those of various
philosophers and philosophically inclined scientists. A
full enumeration of these points of contact would require
me to begin with Spinoza. That my starting-point is not
essentially different from Hume's is of course obvious. I
differ from Comte in holding that the psychological facts
are, as sources of knowledge, at least as important as the
physical facts. My position, moreover, borders closely on
that of the representatives of the philosophy of immanence.
This is especially true in the case of Schuppe, with whose
writings I became acquainted in 1902 ; his Outline of
Theory of Knoiuledge and Logic, a work which is packed
with thought and which can be read without a special
dictionary, struck a particularly sympathetic chord in me.
In this book I have found scarcely anything to which,
perhaps with some small modification, I cannot yield a
hearty assent. To be sure, his conception of the Ego
constitutes a point of difference between us ; but not a
point on which it would be hopeless to reach an under-
standing. As to the views of Avenarius, the affinity
between them and my own is as great as can possibly be
46
THE ANALYSIS OF SENSATIONS 47
imagined where two writers have undergone a different
process of development, work in different fields, and are
completely independent of one another. The agreement
is somewhat obscured by the great difference of form.
Avenarius presents us with a scheme, exhaustive indeed
but highly generalized, which is made more difficult to
grasp by a strange and unfamiliar terminology. For con-
structions of this kind I had neither occasion nor vocation,
neither inclination nor talent; I am a scientist and not
a philosopher. What I aimed at was merely to attain a
safe and clear philosophical standpoint, whence practicable
paths, shrouded in no metaphysical clouds, might be seen
leading not only into the field of physics but also into that
of psycho-physiology. With the attainment of this, my
battle was won. Although my theory is the fruit of long
years of meditation from earliest youth upwards, yet in its
brevity it has the form of a mere aperfu, nor shall I be
offended if it is regarded in that light. I willingly admit
that in my distaste for an artificial terminology I have
perhaps fallen into the opposite extreme to that of Avenarius.
While Avenarius is often not to be understood, or only
to be understood after much study, my words have often
enough been misunderstood. one acute critic considers
that many of my results are results which I ought not to
have reached (he is therefore in a position to save himself
the trouble of investigation, since he already knows the
results to which investigation ought to lead), and proceeds
to reproach me with being difficult to place, since I use
ordinary language, and it is consequently impossible to see
to what "system" I adhere. Thus, first and foremost,
you have to choose a system ; then within the walls of that
48 THE ANALYSIS OF SENSATIONS
system you may think and speak. In this way all kinds
of current popular views have been comfortably read into
my words ; I have been accused of idealism, Berkeleyanism,
even of materialism, and of other " -isms," of all of which
I believe myself to be innocent.
The fact is that each of the two methods of exposition
has its advantages and disadvantages. But the difference
of form has had a prejudicial effect also on the mutual
understanding between Avenarius and myself. I recognized
the affinity between our views at a very early stage, and
expressed my conviction of it in the Mechanik (1883) and
in the first edition of this book (1886), although at that
time I was only able to refer to one of Avenarius' minor
works (Denken der Welt nach dem Prinzip des kleinsten
J^ra/f masses), which had appeared in 1876 and had acci-
dentally come in my way shortly before the publication of
my Mechanik. It was only in 1888, 1891, and 1894,
by means of Avenarius' publications, Kritik der reinen
Erfahrung, Der menschliche Weltbegriff, and his psycho-
logical articles in the Vierteljahrsschrift, that the similarity
of our tendencies was fully revealed to me. As to the
first of these works, however, its somewhat hypermeta-
phorical terminology prevented me from tasting the full
rapture of agreement. It is asking rather much of an
elderly man that to the labour of learning the languages of
the nations he should add that of learning the language of
an individual. It was consequently reserved for the
younger generation to turn the work of Avenarius to
good use : in this connexion I am glad to be able to refer
to the writings of H. Cornelius, C. Hauptmann and J.
Petzoldt, which are in a fair way to bring to light and
THE ANALYSIS OF SENSATIONS 49
to develop further the real value of Avenarius' work.
Avenarius, too, acknowledged on his side the affinity
between us, and noticed it in the books that appeared
from 1888 to 1895. Yet with him, too, the conviction of
a profounder coincidence of view between us seems, as
I am forced to infer from remarks made by him in the
past to third persons, only to have been developed
gradually. The man himself I have never known person-
ally. Unmistakable efforts are being made to minimize
his importance, but, in spite of that, acquaintance with
his works is, I am glad to say, on the increase,
2.
I should now like to indicate more particularly those
points of agreement between us to which I attach import-
ance. The economy of thought, the economical repre-
sentation of the actual, this was indicated by me, in
summary fashion first in 1871 and 1872, as being the
essential task of science, and in 1882 and 1883 I gave
considerably enlarged expositions of this idea. As I have
shewn elsewhere, this conception, which implicitly contains
and anticipates KirchhofPs notion of "perfectly simple
description" (1874), was by no means quite new; it can
be traced back to Adam Smith, and, as P. Volkmann holds,
in its beginnings even to Newton. We find the same con-
ception again, with the exception of one feature that does
not come out clearly, fully developed in Avenarius (1876).
A broad foundation is laid for the theory in question,
and light is shed upon it from new sides, if, in conformity
with the stimulus given by Darwinism, we conceive of all
50 THE ANALYSIS OF SENSATIONS
psychical life including science as biological appearance,
and if we apply to the theory the Darwinian conceptions of
struggle for existence, of development, and of selection.
The theory is inseparable from the hypothesis that each
and every psychical entity is physically founded and
determined. Now, in his Kritik der reinen Erfahrung,
Avenarius tries to shew in detail that all theoretical and
practical activity is determined by change in the central
nervous system. In doing this he is merely basing him-
self on the very general assumption that the central organ
is subject to an impulse of self-preservation, a tendency to
maintain its equilibrium, not only as a whole, but also in
its parts. This agrees very well with the conceptions
developed by Hering as to the behaviour of living sub-
stance. In holding these views, Avenarius is brought into
close contact with modern positive research, particularly
in physiology. In my writings too, opinions of a corre-
sponding nature, briefly indeed, but definitely expressed,
appeared as long ago as 1863, and in 1883 I expounded
these opinions at greater length, though without develop-
ing a complete system, such as we find in Avenarius.
But it is to our agreement in the conception of the
relation between the physical and the psychical that I
attach the greatest importance. For me this is the main
point at issue. It was by means of his psychological
articles that I first became convinced of this coincidence
between Avenarius and myself. In order to be sure of
making no mistake, I addressed an inquiry on the subject
to Dr. Rudolf Wlassak, who I knew would be intimately
acquainted with Avenarius' standpoint, thanks to his associa-
tion with him for many years. His reply was as follows :
THE ANALYSIS OF SENSATIONS 51
"The conception of the relation of 'the physical' to
* the psychical ' is identical in Avenarius and Mach. Both
come to the conclusion that the difference between the
physical and the psychical consists solely in the difference
of the relations of dependence, which on the one hand are
the objects dealt with by Physics (in the widest sense of
the word), and on the other are the objects dealt with by
psychology. If I investigate the dependence of one con-
stituent (A) of an environment on another constituent ()
of an environment, I am studying physics ; if I inquire to
what extent A is changed by a change in the sense-organs
or the central nervous system, I am studying psychology.
Avenarius has accordingly proposed to abolish the terms
' physical ' and ' psychical ' and in future only to speak of
physical and psychological dependencies ("Observations,"
Vierteljahrsschrift) xix., p. 18). In Mach's work the same
view occurs, except that (?) the untenability of the old
conception of the psychical, and consequently of the proper
task of psychology, is not demonstrated.
" This task is performed by the exposure of ' Introjection/
or rather of the fallacy in formal logic which underlies
introjection. Avenarius starts from the fact that naive
realism, 'the natural view of the world,' stands at the
beginning of all philosophizing. Within the limits of this
natural view of the world it is possible for a relative
delimitation of the complex 'self and the complex 'en-
vironment ' to be carried out without necessarily involving
the 'dualism' of 'body' and 'soul,' since, from the
standpoint of naive realism, the constituents that belong to
the 'self,' to one's own body, are through and through
comparable with the constituents of the environment.
52 THE ANALYSIS OF SENSATIONS
Even when the preliminary survey has advanced to the
formation of concepts of substance (Mach, Analysts of
Sensations^ p. 5), this does not mean that a complete and
essential difference between body and soul is given. The
final splitting up of the world, originally conceived by naive
realism as a unity, is really occasioned, according to
Avenarius, by the interpretation of the utterances of our
fellow-men. As long as I say, ' the tree does not exist for
me alone ; it also, as their utterances permit me to assume,
exists for my fellow-men mthe same way as it exists for me,'
I am in no wise overstepping the analogy which formal
logic allows between me and my fellow-men. But I am
overstepping this analogy, if I say that the tree exists as
* a copy,' ( a sensation ' or ' a presentation ' in my fellow-
men, if I introduce or introject the tree ; since I am then
assuming something for my fellow-men which I cannot dis-
cover in my own experience, which always shews me the
constituents of my environment as standing in a definite
relation to my body, and never as being in my consciousness
or the like. Inasmuch as introjection is a way of passing
beyond experience, every attempt to bring it into harmony
with the facts of experience must become an inexhaustible
' source of pseudo-problems. This is most clearly seen in
the different forms which, in the course of the history of
philosophy, introjection has assumed. The oldest and
crudest theories of perception exhibited it in its crudest and
simplest form ; they supposed that copies were detached from
objects, and that these copies penetrated within the body.
Now in so far as it is recognized that the constituents of the
environment are not present inside the body in the same
way as they are present outside it, to that extent they are
THE ANALYSIS OF SENSATIONS 53
bound, the moment they are inside it, to become something
essentially different from the environment. The root of
dualism lies in the extension of introjection, in the attempt to
bring it into harmony with the complex of the environment.
" It may be doubted whether Avenarius' account of the
motives for introjection is satisfactory in all cases. He
holds that introjection is always connected with the ex-
planation of the * perceptions ' of one's fellow-men. But
it might well be urged that the fact that one and the same
constituent of the environment is at one time given in
sensations as a 'thing,' and at another given as a memory,
can be sufficient motive for conceiving this constituent as
being present twice over, namely, first ' materially ' in the
environment, and secondly in my 'consciousness,' in my
* soul.' Another point to be considered is, whether dream-
experiencies cannot equally constitute, at a primitive stage
of culture, an independent motive for dualism. 1 Avenarius,
indeed, represents introjection as the presupposition of the
dualist's interpretation of dream-experiences, but without
adducing conclusive reasons. But it is not justifiable to
regard prehistoric animism as the root of dualism, if by
' animism ' we understand merely the hypothesis that all
the lifeless constituents of our environment are beings like
ourselves. As long as deeper-lying physiological reasons
do not make it impossible, the * natural view of the world '
can also provide a foundation for the hypothesis that, in
the case of the tree, for example, the constituents of its
environment exist for it in the same sense as they do for
human beings. In other words : Anyone who held the
1 According to Tylor, they are in fact one of the strongest motives
(Mach).
54 THE ANALYSIS OF SENSATIONS
view of the psychical common to Avenarius and Mach,
might, if he were entirely ignorant of physiology, suppose
that a tree or a stone touches and sees its environment.
In that case he would still not be a dualist. He only
becomes a dualist when, in order to explain this touching
and seeing on the part of the tree or stone, he assumes that
the constituents of the environment, which the tree and
stone taste and see, are present over again in the tree as its
' sensations ' or its ' consciousness/ It is only then that
the world is duplicated by division into a spiritual part and
a material part.
" The discovery of the illegitimacy of introjection throws
light in two directions. on the one hand it is illuminating
on the side of theory of knowledge. All problems con-
nected with the relation of our 'sensations,' 'presenta-
tions ' and ' contents of consciousness ' to the material
things, of which the above-mentioned products of intro-
jection are supposed to be the 'copies,' 'signs,' and so
forth, are seen to be merely illusory. Instances of such
pseudo-problems are the problems as to projection which
we meet in theories of space, the exteriorization of the
space-sensations, etc.
" on the other hand, the elimination of introjection implies
that all psychology which is not physiological is illegitimate.
When I have recognized that the ' contents of conscious-
ness,' the 'psychic processes,' which accompany changes
in the nervous system, are nothing more than constituents
of my environment which I have introduced into my fellow-
men and ultimately also into myself, it is impossible for
me to look for anything in the nervous system except
physiological processes. All special psychical causality
THE ANALYSIS OF SENSATIONS 55
disappears ; all those problems disappear which are con-
nected with the question whether the intervention of
psychical forces in the physiological processes of the brain
is compatible with the principle of the conservation of
energy. 1
" When such a phrase is used as ' the continued existence
of presentations without their being in consciousness '
(Mach, Wdrmekhre p. 441), this is, strictly speaking, only
legitimate as an abbreviated ｅxpression for particular
processes of the central nervous system, and in any case it
savours strongly of dualistic conceptions."
The remaining difference between the way in which
Avenarius puts his views and the way in which I put mine
can be reduced to elements which are easily grasped. In
the first place, it was not my intention to give a complete
exposition of the development of my point of view out
of the preceding phrases of philosophical reflection about
the world. In the second place, Avenarius starts from a
1 I cannot refrain from here expressing my surprise that the principle
of the conservation of energy has so often been dragged in in connexion
with the question whether there is a special psychical agent. on the
assumption that energy is constant, the course of physical processes is
limited, but not necessarily determined with perfect uniqueness. That
the principle of conservation of energy is satisfied in all physiological
cases, merely tells us that the soul neither uses up work nor performs
it. For all that, the soul may still be a partly determinant factor.
When the philosopher asks a question which has reference to this case,
he usually misses the point of the principle of the conservation of
energy, and the stock reply of the physicist has no intelligible meaning
in relation to a case so far removed from the scope of his ideas. Cp.
the references to a similar discussion in Hofler's Psychologic, 1897,
pp. 58 sqq., note. Apart from the above considerations, the assump-
tion of a special psychical agent appears to me to be a presupposition
which is unfortunate and can only do harm by making investigation
difficult ; it is moreover unnecessary and improbable (Mach).
56 THE ANALYSIS OF SENSATIONS
realistic phase ; I, on the other hand, started from an idealist
phase (p. 30, above, footnote), such as I actually went
through in my early youth. In that way I might easily have
talked, for instance, about the elimination of " extrajection "
(pp. 6, 12-22, 29-35, 43> above). In the third place, it is
not necessary to attribute so important a role to the inter-
pretation of our fellow-men by means of introjection in the
bad sense, until after the new standpoint has been reached \
and then it is also not necessary to exclude this introjection
again. A solitary thinker might reach the new standpoint,
and even he, as Wlassak observes, might have to rise
superior to dualistic tendencies. But this standpoint once
reached, and the varying character of the dependence . of
the elements once recognized as the essential point, the
question whether we start from a phase of realism or of
idealism is of no greater importance for us than a change
in the fundamental variables of his equations is for the
mathematician or physicist.
What Avenarius puts forward, and consequently what I
also put forward, appears to me to contain scarcely any-
thing that is not self-evident self-evident at least for every
man who has shaken himself free from the pressure of " the
legacy of wild philosophy," as Tylor calls it. Science has
always required such self-evident propositions as a safe
foundation upon which to build. When I see the paths
pursued by different philosophical thinkers converging, and
especially when I contemplate the close coincidence
between general philosophical views and the views of
scientific specialists, I think that I am justified in detecting
here a hopeful presage of the mutual accommodation of
the sciences to one another.
IV. THE CHIEF POINTS OF VIEW
FOR THE INVESTIGATION OF
THE SENSES.
i.
IN order to get our bearings, we will now try to obtain,
from the standpoint we have reached, a broad view
of the special problems that will engage our attention.
When once the inquiring intellect has formed, through
adaptation, the habit of connecting two things, A and
B , in thought, it tries to retain this habit as far as pos-
sible, even where the circumstances are slightly altered.
Wherever A appears, B is added in thought. The prin-
ciple thus expressed, which has its root in an effort for
economy, and is particularly noticeable in the work of the
great investigators, may be termed the principle of continuity .
Every actually observed variation in the connexion of A
and B which is sufficiently large to be noticed makes itself
felt as a disturbance of the above-mentioned habit, and
continues to do so until the habit is sufficiently modified
to prevent the disturbance being felt. Suppose, for in-
stance, that we have become accustomed to seeing light
deflected when it impinges on the boundary between air and
glass. But these deflections vary noticeably in different
tiases, and the habit formed by observing some cases
cannot be transferred undisturbed to new cases, until we
are able to associate with every particular angle of in-
cidence (A) a particular angle of refraction (B\ which we
57
58 THE ANALYSIS OF SENSATIONS
are able to do by discovering the so-called law of refraction,
and by making ourselves familiar with- the rules contained
in that law. Thus another and modifying principle con-
fronts that of continuity ; we will call it the principle of
sufficient determination, or sufficient differentiation.
The joint action of the two principles may be very well
illustrated by a further analysis of the example cited. In
order to deal with the phenomena exhibited in the change
of color of light, the idea of the law of refraction must be
retained, but with every particular color a particular index
of refraction must be associated. We soon perceive that
with every particular temperature also, a particular index of
refraction must be associated ; and so on.
In the end, this process leads to temporary contentment and
satisfaction, the two things A and B being conceived as so con-
nected that to every change of the one that can be observed at
any moment there corresponds an appropriate change of the
other. It may happen that both A and B are conceived as
complexes of components, and that to every particular com-
ponent ofAa. particular component of B corresponds. This
occurs, for example, when B is a spectrum, and A the cor-
responding sample of a compound to be tested, in which case
to every component part of the spectrum one of the com-
ponents of the matter volatilized before the spectroscope is
correlated, independently of the others. only through com-
plete familiarity with this relation can the principle of sufficient
determination be satisfied.
2.
Suppose, now, that we are considering a color-sensation
B, not in its dependence on A, the heated matter tested,
THE ANALYSIS OF SENSATIONS 59
but in its dependence on the elements of the retinal process,
N. By doing this we change, not the kind, but only the direc-
tion of our point of view. None of the preceding observations
lose their force, and the principles to be followed remain the
same. And this holds good, of course, of all sensations.
Now, sensation may be analysed in itself, immediately,
that is, psychologically (which was the course adopted by
Johannes Millie r), or the physical (physiological) processes
correlated with it may be investigated according to the
methods of physics (the course usually preferred by the
modern school of physiologists), or, finally, the connexion
of psychologically observable data with the corresponding
physical (physiological) processes may be followed up a
mode of procedure which will carry us farthest, since in this
method observation is directed to all sides, and one investi-
gation serves to support the other. We shall endeavor to
attain this last-named end wherever it appears practicable.
This being our object, then, it is evident that the principle
of continuity and that of sufficient determination can be satis-
fied only on the condition that with the same B (this or that
sensation) we always associate the same N (the same nerve-
process) and discover for every observable change of B a cor-
responding change of N. \iB is psychologically analysable
into a number of independent components, then we shall rest
satisfied only on the discovery, in N, of equivalent components
corresponding to these. If, on the other hand, properties or
aspects have to be noticed in B which cannot appear in isola-
tion, as, for instance, pitch and intensity in tones, we shall
have to expect the same state of things in N. In a word,
for all psychically observable details of B we have to seek
the correlated physical details of N.
60 THE ANALYSIS OF SENSATIONS
I do not of course maintain that a (psychologically)
simple sensation cannot also be conditioned by very
complicated circumstances. For the circumstances would
hang together like the links of a chain and would not issue
in a sensation, unless the chain extended to the nerve.
But since the sensation may also appear in the form of a
hallucination, namely when no physically conditioned
circumstances are present outside the body, we see that a
certain nervous process, as the final link in the chain, is
the essential and immediate condition of the sensation.
Now we cannot think of this immediate condition as
being varied without conceiving of the sensation as being
varied, and vice versa. For the connexion between this final
link and the sensation we will regard the principle which
we have laid down as valid.
We may thus establish a guiding principle for the
investigation of the sensations. This may be termed the
principle of the complete parallelism of the psychical and
physical. According to our fundamental conception, which
recognizes no gulf between the two provinces (the
psychical and the physical), this principle is almost a matter
of course ; but we may also enunciate it, as I did years ago,
without the help of this fundamental conception, as a
heuristic principle of research. 1
The principle of which I am here making use goes further
than the widespread general belief that a physical entity cor-
responds to every psychical entity and vice versa ; it is much
1 Compare ifiy paper, Ueber die Wirkung der raumlichen Vertheilung
des Lichtreizes aufdie Netzhaut (Sitzungsberichte der Wiener Akadamie,
THE ANALYSIS OF SENSATIONS 61
more specialized. The general belief in question has been
proved to be correct in many cases, and may be held to be pro-
bably correct in all cases ; it constitutes moreover the neces-
sary presupposition of all exact research. At the same time
the view here advocated is different from Fechner's concep-
tion of the physical and psychical as two different aspects
of one and the same reality. In the first place, our view
has no metaphysical background, but corresponds only
to the generalized ｅxpression of experiences. Again, we
refuse to distinguish two different aspects of an unknown
tertium quid ; the elements given in experience, whose con-
nexion we are investigating, are always the same, and
are of only one nature, though they appear, according to
the nature of the connexion, at one moment as physical
and at another as psychical elements. 1 I have been asked
whether the parallelism between psychical and physical is
not meaningless and a mere tautology, if the psychical and
physical are not regarded as essentially different. The
question arises from a misunderstanding of the analysis
which I have given above. When I see a green leaf (an
Vol. LIL, 1865) ; further Reichert's und Dtibois' Archiv, 1865, p. 634,
and Grundlinien der Lehre von den Bewegimgsempfindungen (Leipzig,
Engelmann, 1875, p. 63). The principle is also implicitly contained in
an article of mine in Fichte's Zeitschrift filr Philosophic (Vol. XLVI.,
1865, p. 5), which is printed also in my Popular Scientific Lectures ,
Chicago, Open Court Publishing Co.
1 For the various aspects of the problem of parallelism, see C.
Stumpf's address to the Psychological Congress at Munich (Munich,
1897); G. Heymans, "Zur Parallelismusfrage," Zeitschrift filr
Psychologie der Sinnesorgane, Vol. XVII. ; O. Kiilpe, Ueber die Bezie-
hung z-wischen kb'rpcrlichen und seelischen Vorgangen, Zeitschrift fur
Hypnotismus, Vol. VII., J. von Kries, Uber die materiellen Grund-
lagen der Bewiisstseinserscheimmgen^ Freiburg im Breisgau, 1898; C.
Hauptmann, Die Metaphysik in der Psychologie ', Dresden, 1893.
62 THE ANALYSIS OF SENSATIONS
event which is conditioned by certain brain-processes) the
leaf is of course different in its form and color from the
forms, colors, etc., which I discover in investigating a
brain, although all forms, colors, etc., are of like nature
in themselves, being in themselves neither psychical nor
physical. The leaf which I see, considered as dependent
on the brain-process, is something psychical, while this
brain-process itself represents, in the connexion of its
elements, something physical. And the principle of
parallelism holds good for the dependence of the former
immediately given group of elements on the latter group,
which is only ascertained by means of a physical
investigation which may be extremely complicated (cp.
p. 44).
I have perhaps stated the principle in rather too abstract
a form. A few concrete examples may now help to explain
it. Wherever I have a sensation of space, whether through
the sensation of sight or through that of touch, or in
any other way, I am obliged to assume the presence of
a nerve-process of the same kind in all cases. For all
time-sensations, also, I must suppose like nerve-processes.
If I see figures which are the same in size and shape
but differently colored, I seek, in connexion with the
different color-sensations, certain identical space-sensations
and corresponding identical nerve - processes. If two
figures are similar (that is, if they yield partly identical
space-sensations) then the corresponding nerve-processes
also contain partly identical components. If two different
melodies have the same rhythm, then, side by side with
THE ANALYSIS OF SENSATIONS 63
the different tone-sensations there exists in both cases an
identical time-sensation with identical corresponding nerve-
processes. If two melodies of different pitch are identical,
then the tone-sensations as well as their physiological con-
ditions, have, in spite of the different pitch, identical
constituents. If the seemingly limitless multiplicity of
color-sensations is susceptible of being reduced, by psycho-
logical analysis (self-observation), to six elements (funda-
mental sensations), a like simplification may be expected
for the system of nerve-processes. If our system of space-
sensations appears in the character of a threefold manifold,
the system of the correlated nerve-processes will likewise
present itself as such.
This principle has, moreover, always been more or less
consciously, more or less consistently, followed.
For example, when Helmholtz 1 assumes for every tone-
sensation a special nerve-fibre (with its appurtenant nerve-
process), when he resolves clangs, or compound sounds,
into tone - sensations, when he reduces the affinity of
compound tones to the presence of like tone-sensations
(and nerve-processes), we have in this method of procedure a
practical illustration of our principle. It is only the applica-
tion that is not complete, as will be later shown. Brewster, 2
1 Helmholtz, Die Lehre von den Tonempfimkingen, Brunswick,
Vieweg, 1863. English translation by Alex. J. Ellis, London,
Longmans, Green, & Co., 2nd edition, 1885.
2 Brewster, A Treatise on Optics, London, 1831. Brewster regarded
the red, yellow, and blue light as extending over the whole solar
spectrum, though distributed there with varying intensity, so that,
to the eye, red appears at both ends (the red and the violet), yellow
in the middle, and blue at the end of greater refrangibility,
64 THE ANALYSIS OF SENSATIONS
guided by a psychological but defective analysis of color-
sensations, and by imperfect physical experiments, 1 was
led to the view that, corresponding to the three sensations,
red, yellow, and blue, there existed likewise physically
only three kinds of light, and that, therefore, Newton's
assumption of an unlimited number of kinds of light, with
a continuous series of refractive indices, was erroneous.
Brewster might easily fall into the error of regarding green
as a compound sensation. But had he reflected that color-
sensations may occur entirely without physical light, he
would have confined his conclusions to the nerve-process
and left untouched Newton's assumptions in the province of
physics, which are as well founded as his own. Thomas
Young corrected this error, at least in principle. He
perceived that an unlimited number of kinds of physical
light with a continuous series of refractive indices (and wave-
lengths) was compatible with a small number of color-
sensations and nerve-processes, that a discrete number of
color-sensations did answer to the continuum of deflexions
in the prism (to the continuum of the space-sensations).
But even Young did not apply the principle with full
consciousness or strict consistency, wholly apart from the
fact that he allowed himself to be misled, in his psycho-
logical analysis, by physical prejudices. Even he first
assumed, as fundamental sensations, red, yellow, and blue,
for which he later substituted red, green, and violet
misled, as Alfred Mayer, of Hoboken, has admirably
1 Brewster believed that he was able to alter by absorption the
nuances of the spectrum colors regarded by Newton as simple
a result which, if correct, would really destroy the Newtonian con-
ception. He experimented, however, as Helmholtz (Physiological
Optics) has shown, with an impure spectrum.
THE ANALYSIS OF SENSATIONS 65
shown, 1 by a physical error of Wollaston's. The direction
in which the theory of color- sensation, which has reached a
high degree of perfection through Hering, has still to be
modified, was pointed out by me many years ago in
another place.
6.
Here I will merely state shortly what I have to say
concerning the treatment of the theory of color-sensation.
We frequently meet with the assertion, in recent works, that
1 Philosophical Magazine, February 1876, p. in. Wollaston was
the first to notice (1802) the dark lines of the spectrum, later named
after Fraunhofer, and believed that he saw his narrow spectrum divided
by the strongest of these lines into a red, a green, and a violet part.
He regarded these lines as the dividing lines of the physical colors.
Young took up this conception, and substituted for his fundamental
sensations red, yellow, and blue, the colors red, green, and violet.
Thus, in his first conception, Young regarded green as a composite
sensation, in his second, both green and violet as simple. The question-
able results which psychological analysis may thus yield, are well
calculated to destroy belief in its usefulness in general. But we must
not forget that there is no principle in the application of which error is
excluded. Here, too, practice must determine. The circumstance
that the physical conditions of sensation almost always give rise to
composite sensations, and that the components of sensation seldom
make their appearance separately, renders psychological analysis very
difficult. Thus, green is a simple sensation ; a given pigment or
spectrum-green, however, will as a rule excite also a concomitant
yellow or blue sensation, and thus favor the erroneous idea (based
upon the results of pigment-mixing) that the sensation of green is
compounded of yellow and blue. Careful physical study, therefore, is
also an indispensable requisite of psychological analysis. on the other
hand, physical observation must not be overestimated. The mere
observation that a yellow and blue pigment mixed, yield a green pig-
ment, cannot by itself determine us to see yellow and blue in green,
unless one or the other color is actually contained in it. Certainly no
one sees yellow and blue in white, although, as a fact, spectrum-yellow
and spectrum-blue mixed give white.
B
66 THE ANALYSIS OF SENSATIONS
the six fundamental color-sensations, white, black, red,
green, yellow, blue, which Hering adopted, were first
proposed by Leonardo da Vinci, and later by Mach and
Aubert. From the very first it seemed to me highly
probable, in view of the conceptions prevalent at this time,
that the assertion was founded upon an error, as far as
Leonardo da Vinci was concerned. Let us hear what he
himself says in his Book of Painting (Nos. 254 and 255 in
the translation of Heinrich Ludwig, Quellenschriften zur
Kunstgeschichte, Vienna, Braumiiller, 1882, Vol. XVIII. ).
" 254. Of simple colors there are six. The first of these
is white, although philosophers admit neither white nor
black into the number of colors, since the one is the cause
of color, the other of its absence. But, inasmuch as the
painter cannot do without them, we shall include these two
also among the other colors and say that white in this
classification is the first among the simple colors, yellow
the second, green the third, blue the fourth, red the fifth,
black the sixth. And the white we will let represent the
light, without which one can see no color, the yellow the
earth, the green the water, blue the air, red fire, and black
the darkness which is above the element of fire, because in
that place there is no matter or solid substance upon which
the sunbeams can exert their force, and which as a result
they might illumine." "255. Blue and green are not
simple colors by themselves. For blue is composed of
light and darkness, as, the blue of the air, which is made
up of the most perfect black and perfectly pure white."
" Green is composed of a simple and a composite color,
namely, of yellow and blue." This will suffice to show that
Leonardo da Vinci is concerned partly with observations
THE ANALYSIS OF SENSATIONS 67
concerning pigments, partly with conceptions of natural
philosophy, but not with the subject of fundamental color-
sensations. The many remarkable and subtle scientific
observations of all sorts which are contained in Leonardo
da Vinci's book lead to the conviction that the artists, and
among them especially he himself, were the true forerunners
of the great scientists who came soon afterwards, These
men were obliged to understand nature in order to reproduce
it agreeably; they observed themselves and others in the
interest of pure pleasure. Yet Leonardo was far from being
the author of all the discoveries and inventions which
Groth, for example (Leonardo da Vinci ah Ingenieur und
Philosophy Berlin, 1874), ascribes to him. 1 My own
scattered remarks concerning the theory of color-sensations
were perfectly clear. I assumed the fundamental sensations
white, black, red, yellow, green, blue, and six different
corrresponding (chemical) processes (not nerve-fibres) in
the retina. (Compare Reicherfs und Dubois 1 Archiv^ 1865,
P' 633, et seq.) As a physicist, I was of course familiar
with the relation of the complementary colors. My con-
ception, however, was that the two complementary processes
together excited a new the white process. (Loc. cit. t
p. 634.) I gladly acknowledge the great advantages of
Hering's theory. They consist for me in the following.
First, the black process is regarded as a reaction against the
white process ; I can appreciate all the better the facilita-
tion involved in this, as it was just the relation of black
and white that for me presented the greatest difficulty.
Further, red and green, as also yellow and blue, are
1 Marie Herzfeld, Leonardo da Vinci, Auswahl aus den veroffent-
lichten Handschriften^ Leipzig, 1904.
68 THE ANALYSIS OF SENSATIONS
regarded as antagonistic processes which do not produce
a new process, but mutually annihilate each other. Ac-
cording to this conception white is not subsequently
produced but is already present beforehand, and still
survives on the annihilation of a color by the comple-
mentary color. The only point that still dissatisfies me
in Hering's theory is that it is difficult to perceive why
the two opposed processes of black and white may be
simultaneously produced and simultaneously felt, while
such is not the case with red-green and blue-yellow.
This objection has been partly removed by a further
development of Hering's theory. 1 The full explanation of
this relation lies undoubtedly in
the proof, which W. Pauli has
provided, that certain processes
l n colloidal and in living sub-
b stances can be reversed by opposite
processes along the same path, or
"homodromously," as in A, while other processes can only
be reversed by opposite processes along a different path,
or " heterodromously," as in J2. 2 I myself shewed long
ago that certain sensations are related to one another as
positive and negative magnitudes (e.g., red and green),
while others do not stand in this relation (e.g., white and
black). 3 Now all difficulties are reconciled if we suppose
1 Zur Lehre vom Lichtsinne, Vienna, 1878, p. 122. Cp. also my
paper, previously cited, in the Sitzungsberichte der Wiener Akademie,
Vol. LIL, 1865, October.
2 W. Pauli, Der Kolliodah Zustand und die Vorgange in der
lebendigen Substanz, Brunswick, Vieweg, 1902, pp. 22, 30.
3 Grundlinicn der Lehre von den Bewegungsempfindungen, 1895,
PP- 57 , sqq.
THE ANALYSIS OF SENSATIONS 69
with Pauli that the opposed processes as assumed by Hering,
which correspond to the first pair, are homodromous, and
that the processes underlying the second pair are hetero-
dromous. 1
The examples adduced will suffice to explain the signifi-
cance of the above-enunciated principle of inquiry, and at
the same time to show that this principle is not entirely
new. In formulating the principle, years ago, I had no
other object than that of making quite clear to my
own mind a truth which I had long instinctively felt.
It seemed to me a simple and natural, nay, an almost
self-evident supposition, that similarity must be founded on
a partial likeness or identity, and that consequently, where
sensations were similar, we had to look for their common
identical constituents and for the corresponding common
physiological processes. I wish, however, to make it quite
clear to the reader that this view by no means meets with
universal agreement. We constantly find it maintained in
philosophical books that similarity may be observed without
there being any question at all of such identical con-
stituents. Thus a physiologist 2 can speak as follows of the
principle under discussion : "The application of this prin-
ciple to the above problems leads him (Mach) to ask. what
is the physiological factor that corresponds to the qualities
thus postulated ? Now it seems to me that, of all axioms
1 A recent exposition of Hering's views will be found in Graefe-
Saemisch's Ilandbuck der ges. Aitgenheilkunde, Leipzig, 1905^
Vol. III.
2 J. Von Kries, Ueber die materiellen Grmidlagen der Bewusst-
seinserscheinu-hgcn^ Freiburg im Breisgau, 1898.
70 THE ANALYSIS OF SENSATIONS
and principles, none is more doubtful, none is exposed to
greater misunderstandings than is this principle. If it is
nothing more than a periphrasis for the so-called principle
of parallelism, then it cannot be considered either new or
particularly fruitful, and it does not deserve the importance
that is attached to it. If, on the other hand, it is intended
to mean that a definite element or constituent of a
physiological event must correspond to everything which
we can distinguish as having some sort of psychological
unity, to every relation, to every form, in a word to
everything that we can denote by a general concep-
tion, then this formulation can only be characterized
as dubious and misleading." And I am taken as
holding that the principle in question (with the re-
servation made on p. 59) must be understood in this
last "dubious and misleading" sense. I must leave it
entirely to the reader to choose whether he will
accompany me any further and enter with me on that
preliminary stage of inquiry which is clearly denned by
means of our principle, or whether, bowing to the authority
of my opponents, he will turn back and satisfy himself
merely with considering the difficulties which confront
him. If he chooses the former alternative, he will,
I hope, discover, that when simpler cases have been
disposed of, the difficulties in cases of deeper-lying
abstract similarity no longer appear in such a formidable
light as before. All I will add at present is, that in these
more] complicated cases of similarity the similarity arises
not from the presence of one common element, but from a
common system of elements, as I shall explain at length
in connexion with conceptual thinking (Cf. Chap. XIV.).
THE ANALYSIS OF SENSATIONS 71
8.
As we recognize no real gulf between the physical and
the psychical, it is a matter of course that, in the study
of the sense-organs, general physical as well as special
biological observations may be employed. Much that
appears to us difficult of comprehension when we draw a
parallel between a sense-organ and a physical apparatus,
is rendered quite obvious in the light of the theory of
evolution, simply by assuming that we are concerned with
a living organism with particular memories, particular
habits and manners, which owe their origin to a long and
eventful race-history. The sense-organs themselves are a
fragment of soul ; they themselves do part of the psychical
work, and hand over the completed result to conscious-
ness. I will here briefly put together what I have to say
on this subject.
The idea of applying the theory of evolution to physio-
logy in general, and to the physiology of the senses in
particular, was advanced, prior to Darwin, by Spencer
(1855). It received an immense impetus through Darwin's
book The ｅxpression of the Emotions. Later, P. R.
Schuster (1879) discussed the question whether there were
" inherited ideas " in the Darwinian sense. I, too, expressed
myself in favor of the application of the idea of evolution
to the theory of the sense-organs (Sitzungsberichte der
Wiener Akademie, October 1866). one of the finest
and most instructive discussions, in the way of a psycho-
logico-physiological application of the theory of evolution,
72 THE ANALYSIS OF SENSATIONS
is to be found in the Academic Anniversary Address of
Hering, on Memory as a General Function of Organized
Matter ; 1870 (English translation, Open Court Publishing
Company, Chicago, 1913). As a fact, memory and here-
dity almost coincide in one concept if we reflect that
organisms, which were part of the parent-body, emigrate
and become the basis of new individuals. Heredity is
rendered almost as intelligible to us by this thought as,
for example, is the fact that Americans speak English, or
that their state-institutions resemble the English in many
respects, etc. The problem involved in the fact that
organisms possess memory, a property which is apparently
lacking to inorganic matter, is, of course, not affected by
these considerations, but still exists (cp. Chapters V., XL).
If we want to avoid criticizing Hering's theory unfairly, we
must observe that he uses the conception of memory in a
rather broad sense. He perceived the affinity between the
lasting traces imprinted on organisms by their racial history,
and the more evanescent impressions which the individual
life leaves behind it in consciousness. He recognizes that
the spontaneous reappearance, in response to a slight
stimulus, of a process which has once been set up, is
essentially the same event, whether it can be observed
within the narrow framework of consciousness or not.
The perception of this common feature in a long series of
phenomena is an essential step in advance, even though
this fundamental feature itself still remains unexplained. 1
Recently Weismann (Ueber die Dauer des Lebens, 1882)
has conceived death as a phenomenon of heredity. This
admirable book, also, has a very stimulating effect. The
1 R. Semon, Die Mneme, Leipzig, 1904.
THE ANALYSIS OF SENSATIONS 73
difficulty which might be found in the fact that a character-
istic should be inherited which can make its appearance in
the parent-organism only after the process of inheritance is
ended, lies probably only in the manner of statement.
It disappears when we consider that the power of the
somatic cells to multiply can increase, as Weismann shows,
at the cost of the increase of the germ-cells. Accordingly,
we may say that greater length of life on the part of the
cell-society and lessened propagation are two phenomena
of adaptation which mutually condition each other. While
a Gymnasium student, I heard it stated that plants from
the Southern Hemisphere bloom in our latitudes, when it
is spring in their native place. I recall clearly the mental
shock which this communication caused me. If it is true,
we may actually say that plants have a sort of memory,
even though it be admitted that the chief point involved
is the periodicity of the phenomena of life. The so-called
reflex movements of animals may be explained in a natural
manner as phenomena of memory outside the organ of
consciousness. I was a witness of a very remarkable
phenomenon of this kind in 1865, I think with Rollett,
who was experimenting with pigeons whose brains had
been removed. These birds drink whenever their feet are
placed in a cold liquid, whether the liquid is water,
mercury, or sulphuric acid. Now since a bird must
ordinarily wet its feet when it seeks to quench its thirst,
the view arises quite naturally that we have here a habit
adapted to an end, which is conditioned by the mode of
life and fixed by inheritance, and which, even when con-
sciousness is eliminated, takes place with the precision of
clockwork on the application of the stimulus appropriate
74 THE ANALYSIS OF SENSATIONS
to its excitation. Goltz, in his wonderful book Die Ner-
vencentren des Frosches, 1869, and in later writings, has
described many phenomena of the sort. I will take this
opportunity of mentioning some further observations which
I recall with a great deal of pleasure. In the autumn
vacation of 1873, m Y ntt l e DOV brought me a sparrow a
few days old, which had fallen from its nest, and wanted
to bring it up. But the matter was not so easy. The
little creature could not be induced to swallow, and would
certainly soon have succumbed to the indignities that
would have been unavoidable in feeding it by force. I
then fell into the following train of thought : "Whether or
not the Darwinian theory is correct, the new-born child
would certainly perish if it had not the specially formed
organs and inherited impulse to suck, which are brought
into activity quite automatically and mechanically by the
appropriate stimulus. Something similar (in another form)
must exist likewise in the case of the bird." I exerted
myself to discover the appropriate stimulus. A small
insect was stuck upon a sharp stick and swung rapidly
about the head of the bird. Immediately the bird opened
its bill, beat its wings, and eagerly devoured the proffered
food. I had thus discovered the right stimulus for setting
the impulse and the automatic movement free. The
creature grew perceptibly stronger and greedier, it began
to snatch at the food, and once seized an insect that had
accidentally fallen from the stick to the table ; from that
time on it ate, without ceremony, of itself. In proportion
as its intellect and memory developed, a smaller portion of
the stimulus was required. on reaching .independence,
the creature took on, little by little, all the characteristic
THE ANALYSIS OF SENSATIONS 75
ways of sparrows, which it certainly had not learnt by
itself. By day, with its intellect awake, it was very
trustful and friendly. In the evening, other phenomena
were regularly exhibited. It grew timid. It always
sought out the highest places in the room, and would
become quiet only when it was prevented by the ceiling
from going higher. Here again we have an inherited
habit adapted to an end. on the coming of darkness,
its demeanour changed totally. When approached, it
ruffled its feathers, began to hiss, and showed every
appearance of terror and real physical fear of ghosts. Nor
is this fear without its reasons and its purpose in a
creature which, under normal circumstances, may at any
moment be devoured by some monster.
This last observation strengthened me in an opinion
already formed, that my children's terror of ghosts did
not have its source in nursery tales, which were carefully
excluded from them, but was innate. one of my children
would regard with anxiety an arm-chair, which stood in the
shadow ; another carefully avoided, in the evening, a coal-
scuttle by the stove, especially when this stood with the lid
open, looking like gaping jaws. The fear of ghosts is the
true mother of religions. Neither scientific analysis nor
the careful historical criticism of a David Strauss, as applied
to myths, which, for the strong intellect, are refuted even
before they are invented, will all at once do away with and
banish these things. A motive which has so long answered,
and in a measure still answers, to actual economic needs
(fear of something worse, hope of something better), will
long continue to exist in mysterious and uncontrollable in-
stinctive trains of thought. Just as the birds on uninhabited
7 6 THE ANALYSIS OF SENSATIONS
islands (according to Darwin) learn the fear of man only after
the lapse of generations, so we shall unlearn, only after many
generations, that useless habit known as the creeping of flesh.
Every presentation of Faust may teach us the extent to which
we are still in secret sympathy with the conceptions of the
age of witchcraft. The exact knowledge of nature and of the
conditions of this life gradually becomes more useful to man
than fear of the unknown. And in time the most impor-
tant thing of all for him is to be on his guard against his
fellow-men who want to oppress him violently or abuse him
treacherously by misleading his understanding and emotions.
I will here relate one other curious observation, for the
knowledge of which I am indebted to my father (an
enthusiastic Darwinian and in the latter part of his life a
landed proprietor in Carniola). My father occupied him-
self much with silk-culture, raised the yama-mai in the open
oak-woods, etc. The ordinary mulberry silkworm has, for
many generations, been raised indoors, and has consequently
become exceedingly helpless and dependent. When the
time for passing into the chrysalitic state arrives, it is the
custom to give the creatures bundles of straw, upon which
they spin their cocoons. Now it one day occurred to my
father not to prepare the usual bundles of straw for a
colony of silk-worms. The result was that the majority of
the worms perished, and only a small portion, the geniuses
(those with the greatest power of adaptation) spun their
cocoons. Whether, as my sister believes she has observed,
the experiences of one generation are utilized, in noticeable
degree, in the very next generation, is a question which
probably requires to be left to further investigation. The
experiments made by C. Lloyd Morgan (Comparative
THE ANALYSIS OF SENSATIONS 77
Psychology, London, 1894) with young chickens, ducks,
etc., shew that, at any rate in the case of the higher animals,
scarcely anything is innate but the reflexes. The newly-
hatched chick at once begins to peck with great assurance
at everything that it sees ; but it has to learn what is suit-
able to pick up by its individual experience. The simpler
the organism, the smaller the part played by individual
memory. From all these remarkable phenomena we need
derive no mysticism of the Unconscious. A memory
reaching beyond the individual (in the broader sense
defined above) renders them intelligible. A psychology in
the Spencer-Darwinian sense, founded upon the theory of
evolution, but supported by detailed positive investigation,
would yield richer results than all previous speculation has
done. These observations and reflections had long been
made and written down when Schneider's valuable work,
Der thierische Wille, Leipzig, 1880, which contains many
that are similar, made its appearance. I agree with the
details of Schneider's discussions (in so far as they have
not been made problematical by Lloyd Morgan's experi-
ments) almost throughout, although his fundamental con-
ceptions in the realms of natural science with regard to
the relation of sensation and physical process, the signifi-
cance of the survival of species, etc., are essentially different
from mine, and although I hold, for instance, the distinction
between sensation-impulses and perception-impulses to be
quite superfluous. An important revolution in our views
on heredity may perhaps be produced by Weismann's work,
Ueber die Vererbung, Jena, 1883 (English translation, Essays
on Heredity and Kindred Biological Problems, Oxford, The
Clarendon Press, 1889). Weismann regards the inheritance
78 THE ANALYSIS OF SENSATIONS
of traits acquired by use as highly improbable, and finds in
chance variation of the germ-elements and in the selection
of the germ-elements the most important factors. Whatever
attitude we adopt towards Weismann's theories, the dis
cussion initiated by him must contribute to the elucidation
of these questions. No one will refuse to recognize the
almost mathematical acuteness and depth of the way in
which he states the problem, and it cannot be denied that
his arguments have much force. He makes, for instance,
the extremely suggestive remark that it is impossible that
the peculiar and unusual forms of sexless ants, which must
apparently be referred to use and adaptation, and which
moreover deviate so remarkably from the forms of ants
that are capable of propagation, should be produced by
inheritance of characteristics acquired by use. 1 That the
germ-elements themselves may be altered by external in-
fluences appears to be clearly shewn by the formation
of new races, which maintain themselves as such, trans-
mit their racial traits by inheritance, and are themselves,
again, capable of transformation, under other circum-
stances. Accordingly, some influence must certainly be
exerted on the germ-plasm by the body which envelops it
(as Weismann himself admits). Thus an influence of the
individual life upon its descendents can certainly not be
entirely excluded, even although a direct transmission to
the descendents of the results of use in the individual can
(according to Weismann) no longer be expected. In
entertaining the notion that the germ-elements vary acci-
1 But perhaps the powerful mandibles of the sexless ants are the
original acquisition of the species, and merely appear in an atrophied
form in the individuals to whom propagation of the race is confined.
THE ANALYSIS OF SENSATIONS 79
dentally, we must bear in mind that chance is not a principle
of action. When periodic circumstances of different kinds
and different periodicities coincide in accordance with
definite causal laws, the circumstances overlap in such a
way that in any particular case it is impossible to see that
any law is involved. But the law reveals itself with the
lapse of a long enough time, and permits us to calculate on
certain average values or probabilities of effects. 1 Without
some such principle of action, chance or probability is
meaningless. And what principle of action can be con-
ceived as exercising more influence on the variation of the
germ-elements than the body of the parent ? Personally I
cannot understand how it is possible that the species should
succumb to the influence of varying circumstances, and yet
that these circumstances should not affect the individual.
Moreover, I am certain that I myself vary with every
thought, every memory, every experience ; all these factors
undoubtedly change my whole physical behaviour. 2
Although it is scarcely necessary, I should like to add
explicitly that I regard the theory of evolution, in whatever
form, as a working scientific hypothesis, capable of being
modified and of being made more precise, which is valuable
in so far as it facilitates the provisional understanding of
what is given in experience. I have been a witness of the
powerful impetus which Darwin's work gave in my time
not merely to biology, but to all scientific enquiry, and it
is not likely that I should underestimate the value of the
theory of evolution. But I would not quarrel with anyone
1 Vorlesungen ilber Psychophysik, Zeitschrift fur prakt. Heilkunde,
pp. 148, 168, 169, Vienna, 1863.
2 Popular Scientific Lectures, Chicago, Open Court Publishing Co.
8o THE ANALYSIS OF SENSATIONS
who should rate its value very low. As long ago as 1883
and 1886 I dwelt on the necessity of advancing by means
of more precise conceptions obtained by the study of
biological facts for their own sakes. 1 Thus I am by no
means committed to a refusal to understand investigations
such as those of Driesch. But whether Driesch's criticism
of my attitude towards the theory of evolution is justified, 2
I leave to anyone to decide who, even after this criticism,
still cares to be at the pains of reading my works.
10.
Teleological conceptions, as aids to investigation, are not
to be shunned. It is true, our comprehension of the facts
of reality is not enhanced by referring them to an unknown
World-Purpose, itself problematical, or to the equally
problematical purpose of a living being. Nevertheless,
the question as to the value that a given function has for
the existence of an organism, or as to what are its actual
contributions to the preservation of the organism, may be
of great assistance in the comprehension of this function
itself. 3 Of course we must not suppose, on this account,
1 Cp. Popular Scientific Lectures, and Analyse der Empfindungen^
1886, pp. 34, sqq.
2 Driesch, Die organisatorischen Regulationen, pp. 165, sqq., 1901.
3 Such teleological conceptions have often been useful and instructive
to me. The remark, for example, that a visible object under varying
intensity of illumination can be recognized as the same only when the
sensation excited depends on the ratio of the illumination-intensities of
object and surroundings, makes intelligible a whole train of organic
properties of the eye. (Cp. Hering in Graefe-Saemisch's Handbrich der
Augenheilkunde, Vol. III., Ch. 12, pp. 13, sqq.) In this way we under-
stand also, how the organism, in the interest of its survival, was obliged
THE ANALYSIS OF SENSATIONS 81
as many Darwinians have done, that we have " mechanically
explained " a function, when we discover that it is necessary
for the survival of the species. Darwin himself is doubt-
less quite free from this short-sighted conception. By
what physical means a function is developed, still remains
a physical problem ; while the how and why of an organism's
voluntary adaptation continues to be a psychological pro-
blem. The preservation of the species is only one, though
an actual and very valuable, point of departure for inquiry,
but it is by no means the last and the highest. Species
to adjust itself to the requirement mentioned and to adapt itself to feel
the ratios of light-intensity. The so-called law of Weber, or the funda-
mental psycho-physical formula of Fechner, thus appears not as some-
thing fundamental, but as the explicable result of organic adjustments.
The belief in the universal validity of this law is, naturally, herewith
relinquished. I have given the arguments on this point in various
papers. (Sitzungsberichte der Wiener Akademie, Vol. LI I., 1865 ;
Vierteljahrsschrijt fur Psychiatric^ Neuwied and Leipzig, 1868;
Sitzimgsberichte der Wiener Akademie, Vol. LVIL, 1868). In the
last-named paper, proceeding from the postulate of the parallelism
between the psychical and the physical, or, as I then expressed myself,
from the proportionality between stimulus and sensation, I abandoned
the metrical formula of Fechner (the logarithmic law), and brought
forward another conception of the fundamental formula, the validity of
which for light-sensation I never disputed. This is apparent beyond
all doubt from the way in which that paper is worked out. Thus one
cannot say, as Hering has done, that I everywhere take the psycho-
physical law as my foundation, if by this is understood the metrical
formula. How could I have maintained the proportionality between
stimulus and sensation at the same time with the logarithmic depend-
ence? It was sufficient for me to render my meaning clear; to
criticize and contest Fechner's law in detail, I had, for many obvious
reasons, no need. Strictly speaking I consider the ｅxpression "pro-
portionality " also to be inappropriate, since there can be no question
of an actual measurement of the sensations ; all that can be done is to
characterize them exactly and make an inventory of them by numerical
means. Cp. what I have said about the characterization of states of
heat (Prinzipien der Warmelehre, p. 56).
F
82 THE ANALYSIS OF SENSATIONS
have certainly been destroyed, and new ones have as
certainly arisen. The pleasure-seeking and pain-avoiding
will, 1 therefore, is directed perforce beyond the preservation
of the species. It preserves the species when it is advan-
tageous to do so, and destroys it when its survival is no
longer advantageous. Were it directed merely to the
preservation of the species, it would move aimlessly about
in a vicious circle, deceiving both itself and all individuals.
This would be the biological counterpart of the notorious
"perpetual motion" of physics. The same absurdity is
committed by the statesman who regards the state as an
end in itself.
1 Schopenhauer's conception of the relation between Will and Force
can quite well be adopted without seeing anything metaphysical in
either.
V. PHYSICS AND BIOLOGY.
CAUSALITY AND TELEOLOGY.
IT often happens that the development of two different
fields of science goes on side by side for long
periods, without either of them exercising an influence on
the other. on occasion, again, they may come into closer
contact, when it is noticed that unexpected light is thrown
on the doctrines of the one by the doctrines of the other.
In that case a natural tendency may even be manifested
to allow the first field to be completely absorbed in the
second. 1 But the period of buoyant hope, the period of
over-estimation of this relation which is supposed to
explain everything, is quickly followed by a period of
disillusionment, when the two fields in question are once
more separated, and each pursues its own aims, putting
its own special questions and applying its own peculiar
methods. But on both of them the temporary contact
leaves abiding traces behind. Apart from the positive
addition to knowledge, which is not to be despised, the
temporary relation between them brings about a trans-
formation of our conceptions, clarifying them and permitting
of their application over a wider field than that for which
they were originally formed.
1 Cp. W. Pauli, Physikalische-chemische Methods* in der Medizin^
Vienna, 1900, where an allied, but more narrowly limited, question
is dealt with.
83
84 THE ANALYSIS 'OF SENSATIONS
2.
We are living at present in such a period of complicated
cross-relations, and the consequent fermentation of ideas
gives rise to very remarkable phenomena. While many
physicists are concerned to purify physical conceptions by
psychological, logical and mathematical methods, other
physicists, mistrustful of this tendency, and more philo-
sophical than the philosophers themselves, are coming
forward as advocates of the old metaphysical conceptions
which the philosophers have already largely abandoned.
Philosophers, psychologists, biologists, and chemists, all
make the most widely extended applications of the principle
of energy and of other physical conceptions, with a freedom
which the physicist would hardly venture to use in his
own field. We may almost say that the customary roles
of the special departments have been interchanged. The
success of this movement may be partly positive and
partly negative, but in any case the result of it will be a
more precise determination of our conceptions, a more
accurate delimitation of the sphere to which they apply,
and a clearer idea of the difference and the affinity between
the methods of the departments in question.
We are here concerned in particular with the relations
between the physical and biological fields in the broadest
sense. The distinction between effective causes and final
causes, or ends, dates from Aristotle. It has been
generally assumed that physical phenomena are throughout
THE ANALYSIS OF SENSATIONS 85
determined by effective causes, and biological phenomena
by final causes. The acceleration of a body, for example,
is determined solely by the effective causes, by the
circumstances of the movement, such as the presence of
other gravitating magnetic or electrical bodies. Up to the
present we are not able to deduce the development of a
growing animal, or the development of a plant in its peculiar
determinate forms, or the instinctive actions of an animal,
from effective causes alone ; but such facts as these can
be at any rate partially understood when we take into
consideration the purpose of self-preservation under the
particular circumstances of the organism's life. Whatever
theoretical reservations we may make as to the application
to biology of the conception of purpose, it would certainly
be perverse, in a field where the "causality" theory still
affords such imperfect explanations, to refuse to make use
of the clues which a consideration of purpose puts into our
hands. I do not know what it is that compels the cater-
pillar of the hawk-moth to spin a cocoon with a bristly
flap opening outwards, but I see that such a cocoon exactly
corresponds to the purpose of preserving the caterpillar's
existence. I am far from being able to understand
" causally " the numerous remarkable phenomena, described
and studied by Reimarus and Autenrieth, of the develop-
ment and instinctive action of animals ; but I understand
them in the light of the purpose of preserving the animal's
existence in the particular conditions of life involved.
These phenomena consequently merit attention ; they
become fused in the picture which we form of the life of
the organism as ineffaceable constituents ; and it is only
through them that that picture can be rounded out into a
86 THE ANALYSIS OF SENSATIONS
united and connected whole. But it is only quite recently,
and particularly through the investigations of Sachs in
the physiology of plants and, in animal physiology, through
the work of Loeb on geotropism, heliotropism, stereo-
tropism, etc., that the relations between growth and
instinct have been really explained in such a way that we
can begin to conceive these relations also as "causal."
History testifies in a manner that cannot be gainsaid to
the utility of the conception of purpose in biological
research. Consider only Kepler's investigation of the
eye. It was impossible for him, in view of the purpose of
the eye, namely clear vision at different distances, to doubt
the existence of accommodation; but it was not until 150
years later that the processes which effect the accommo-
dation were really discovered. Harvey discovered the
circulation of the blood in the course of an attempt to
make clear to himself the problematical purpose of the
position of the valves of the heart and veins.
Even when a department of facts has been completely
explained teleologically, the need to understand it " causally "
still persists. The belief in the completely different nature
of the two departments we are considering, in virtue of
which one is to be understood only in a causal sense and
the other only in a teleological sense, is not justified. A
complex of physical facts is something simple, or at any
rate in many cases can, at will, be experimentally represented
in such a simple form that the immediate relations between
its parts become visible. Now supposing that we have
done sufficient work in this department to have enabled us
to acquire, as regards the nature of these relations, con-
ceptions which we think correspond to the facts universally,
THE ANALYSIS OF SENSATIONS 87
then we are logically bound to expect that any particular
fact which may present itself will correspond to these con-
ceptions. But this implies no necessity in nature. 1 It is in
this that " causal " understanding consists. A biological
factual complex, on the other hand, is compounded in such
a way that the immediate relations between its parts cannot
be taken in at a glance. Accordingly we are satisfied if we
are able to represent as being connected with one another
prominent parts of the complex which are not immediately
connected. But the intellect which has been trained to
familiarity with the simpler causal relation finds, in the
absence of the intermediate links, difficulties which it tries
to remove as best it can, either by trying to discover these
iniermediate links, or by grasping at the hypothesis of a
quite new kind of connecting relations. The latter alter-
native is unnecessary, if we regard our knowledge as
imperfect and provisional, and reflect that in the department
of physics absolutely analogous cases arise. The scientists
of antiquity, indeed, did not draw this precise distinction
between the two departments. Aristotle, for example, con-
ceives heavy bodies as seeking out their position; Hero
thinks that, from motives of economy, nature conducts light
by the shortest paths and in the shortest times. These
inquirers thus set up no such definite boundary between
the physical and the biological. Moreover, by an imper-
ceptible modification in our thought, we can formulate
every teleological question in such a way as completely to
exclude the conception of purpose. The eye sees clearly
at different distances ; the apparatus of dioptrical vision
1 Prinzipien der Wcirmelehre, 2nd edition, Leipzig, 1900, pp. 434,
457-
88 THE ANALYSIS OF SENSATIONS
must therefore be capable of change ; in what does this
change consist? The valves of the heart and veins all
open in the same direction ; this being so, the circulation
of the blood can only take place in one direction. Is this
the fact ? The modern theory of evolution has made this
sober method of thought its own. Even in the very ad-
vanced parts of physics, on the other hand, we come across
considerations having a great affinity with those of the
biological sciences. The investigation, for example, of the
possibility, under certain conditions, of stationary vibrations
(i.e., vibrations which can maintain themselves) has for some
time past been in an advanced state. It is only quite
recent work, however, which has made clear the manner in
which they arise. 1 We explain the movement of light along
the shortest paths by means of a selection of the affective
paths. At present the conceptions used by chemists are
even closer to those of the biologist. According to these
conceptions all possible combinations are formed by the
resolution of elements ; but combinations which cannot be
resolved, and have greater power of resistance to new attacks,
get the better of the others and survive. It thus would
appear that there is as yet no necessity to assume a funda-
mental difference between teleological and causal methods
of investigation. The former is simply a provisional
method.
5-
To confirm this conclusion in greater detail, let us return
1 Cp. W. C. L. van Schaik, Ueber die Tonerregung in Labialpfeifen.
Rotterdam, 1891 ; V. Hensen, Annalen der Physik, 4th Series, Vol.
III., p. 719, 1900.
THE ANALYSIS OF SENSATIONS 89
to the various conceptions of causality. The old traditional
conception of causality is of something perfectly rigid : a
dose of effect follows on a dose of cause. A sort of
primitive, pharmaceutical conception of the universe is ex-
pressed in this view, as in the doctrine of the four elements.
The very word " cause " makes this clear. The connections
of nature are seldom so simple, that in any given case we
can point to one cause and one effect. I therefore long ago
proposed to replace the conception of cause by the mathe-
matical conception of function, that is to say, by the con-
ception of the dependence of phenomena on one another,
or, more accurately, the dependence of the characteristics of
phenomena on one another. 1 This conception is capable
of any extension or limitation that may be desired, accord-
ing to what is required by the facts under investigation.
Perhaps, therefore, great importance need not be attached
to the objections that have been raised against it. 2 Consider,
as a simple example, the relation of gravitating masses. If
a mass B comes into opposition to a mass A, a movement
of A towards B follows. This is the old formula. But, if
1 Die Geschichte und die Wurzel des Satzes der Erhaltung der Arbeit,
Prague, Calve, 1872. (English translation, History and Root of the
Principle of the Conservation of Energy, by P. E B. Jourdain,
Chicago, Open Court Publishing Co., 1911.)
2 Such objections have been raised by Kiilpe in his Ueber die
Beziehungen zwischen kbrperlichen und seelischen Vorgdngen (Zeitschrift
fur Hypnotismus, Vol. VII., p. 97), also by Cossman in his Empirische
Teleologie, Stuttgart, 1899, p. 22. I do not think that my view differs
so greatly from Cossman's that an understanding is impossible. If he
had considered the matter further, he would have seen that I substituted
the notion of function for the old notion of causality, and that the
notion of function is sufficient also for those cases which he has in view.
I have no further objection to make to his " Empirical teleology." Cp.
also C. Ilauptmann Die Metaphysik in der Physiologic, Dresden, 1893.
go THE ANALYSIS OF SENSATIONS
we consider the matter more accurately, we see that the
masses A B C D. . . determine mutual accelerations in
one another, accelerations which, therefore, are given as
soon as the masses are posited. The accelerations allow us
to infer the velocities which will be attained at some future
moment. Hence also the positions of A B C D. . . are
determined for every moment. But the physical measure-
ment of time is based in its turn upon a measurement of
space, namely the rotation of the earth. We are thus ulti-
mately left with a mutual dependence of positions on one
another. Thus, even in this simplest case, the old formula
is incapable of embracing the multiplicity of the relations
that exist in nature. Similarly in other cases everything is
resolved into relations of mutual dependence, 1 as to the
form of which nothing of course can be said beforehand,
since this is a question which can only be settled by special-
ized inquiry. With a relation of mutual dependence change
is only possible when some group of the related elements
can be regarded as an independent variable. Consequently,
though it may be possible to complete in detail the picture
of the world in a scientifically determined manner when a
sufficient part of the world is given, yet science cannot tell
us what the total result of the world process will be.
Given a well-defined mechanical system (defined, say,
by central forces), with its positions and velocities, its con-
figuration is determined as a function of time. We know
its configuration for any time we like before and after the
time of commencement, and can thus prophesy both back-
wards and forwards. This can only happen in both cases
when no disturbance intervenes from outside, when, that is
1 Cp. Erkenntnis und Irrttim (1905), p. 274.
THE ANALYSIS OF SENSATIONS 91
to say, the system can be regarded as in a certain sense a
closed system. We cannot, indeed, regard any system as
being completely isolated from the rest of the world, inas-
much as the determination of time, and consequently also
that of the velocities, presupposes dependence on a para-
meter which is determined by the path traversed by some
body, such as a planet, lying outside the system. The
actual dependence, even though it be not an immediate
dependence of all processes on the position of one body,
guarantees to us the interconnection of the whole world.
Analogous considerations hold for any physical system,
Fig. i b.
even when it is not conceived as a mechanical system also.
All accurately and clearly recognized relations may be re-
garded as mutual relations of simultaneity.
Let us consider, by way of contrast, the popular concep-
tion of cause and effect. Let 5 in Fig. i, b, represent the sun,
which illumines a body ^placed in any medium whatever.
Then the sun, or the heat of the sun, is the cause of a rise
in temperature in the body K. The rise follows regularly
on the illumination of K. on the other hand, the body
K) or the change in its temperature, cannot be regarded
as the cause of the change in the sun's temperature, as
would actually be the case if S and K stood alone in an
immediate relation to one another. The two changes
would then be simultaneous, and would mutually determine
one another. The reason that this is not so is to be sought
92 THE ANALYSIS OF SENSATIONS
in the intermediate links, the elements, A B, of the
medium, which determine changes not only in K^ but also
in other elements, and in their turn are determined by
these latter. Thus K stands in relations of mutual deter-
mination with innumerable elements, and only a vanishing
portion of the light it reflects finds its way back to the
sun. It is in analogous circumstances that we must
look for the reason why a body K throws an image upon
the retina N^ and sets up a visual sensation E, from which
a memory remains behind, although the memory does not
restore either the retina N or the whole body K. The
principal advantage for me of the notion of function over
that of cause lies in the fact that the former forces us to
greater accuracy of ｅxpression, and that it is free from the
incompleteness, indefmiteness and one-sidedness of the.
latter. The notion of cause is, in fact, a primitive and
provisional way out of a difficulty. Every modern man of
science must, I think, feel this, when, for instance, he
glances at J. S. Mill's discussion of the methods of experi-
mental inquiry. If he were to try to apply these methods
he would never get beyond the most rudimentary results.
The range of spatial and temporal functional relations
within which our conjectures operate, may be one of which
the limits lie very far apart : starting from the present we may
try to prophesy into the distant future or past, and we may
make fortunate guesses. But, the greater the distance, the
less secure must the basis of our reasoning be. It is there-
fore, without prejudice to the greatness of Newton's concep-
tion of action at a distance, a very important step in advance
that modern physics, wherever it can, requires that due con-
sideration should be paid to spatial and temporal continuity.
THE ANALYSIS OF SENSATIONS 93
6.
It might seem from what has been said that, both in
physics and biology, the notion of function was all that we
wanted, and that this notion would prove equal to all
requirements. We need not be alarmed by the great
difference in point of view displayed by the two sciences.
Quite closely related groups of physical phenomena, as for
example frictional electricity and galvanic electricity, look
so different that at first sight it might seem impossible to
expect that the two should be capable of reduction to the
same fundamental facts. The magnetic and chemical
phenomena, which are scarcely observable in the case of
frictional electricity, and could only with difficulty have been
discovered there at all, are extremely prominent in galvanic
electricity ; whereas, contrariwise, it is only in the case of the
former that ponderomotive phenomena and phenomena of
tension present themselves easily and unsought for. Now
it is well known that each of these two studies supplements
and throws great light on the other ; so much so that we
have reached the point of discovering the chemical nature
of frictional electricity by means of galvanic electricity.
An analogous relation also holds between physics and
biology. Both contain the same fundamental facts; but
many sides of these facts come to light only in one of
them, while many other sides are only noticeable in the
other, so that physics, standing side by side with biology,
can afford help to and throw light upon biology, and vice
versa. No one can deny that the application of physics
to biology has accomplished much ; but against these
94 THE ANALYSIS OF SENSATIONS
achievements we have to set other cases in which it was
reserved for biology to bring to light new physical facts
(galvanism, PfefTer's cells, etc.). Physics will accomplish
much more in biology, if only she will submit to have
additions made to her by the latter.
If anyone familiar with the physical sciences alone were
to turn to the study of biology, and thereupon were to
suppose that an animal grows special organs which it finds
ready to be applied to some useful purpose at a later stage
of its life, or that it can perform instinctive actions which it
cannot have learnt and which can only inure to the advan-
tage of future members of the race, or that it adapts its
coloration to its environment in order to avoid possible
future enemies, on such suppositions he would in fact
easily arrive at the assumption that quite peculiar factors
were here at work. one excellent reason why this mysteri-
ous operation of the future at a distance cannot be com-
pared with any physical relation, is that the operation does
not take place exactly and without exception, since many
organisms prepare themselves for a later stage of their life,
but are destroyed before attaining it. It is impossible to
regard something which is not determined for ourselves, or
is only partially determined, namely the uncertain past or
the uncertain future, as being the determining factor in a
present process which is going on before our eyes. But
when we reflect that the processes in the life of generations
return periodically, we see that the conception of a par-
ticular stage of life as being in the future and operating at
THE ANALYSIS OF SENSATIONS 95
a distance is an arbitrary and hazardous conception, and
that the stage of life in question can also be regarded as a
process in the past, as something given which has left its
traces behind. In this way the element of the unfamiliar
and incomprehensible is greatly decreased. What we then
have is not a possible future which might produce an effect,
but a past which certainly has recurred countless times,
and which certainly has produced an effect.
As an example of our contention that Physics is capable
of co-operating fruitfully in the solution of what are appar-
ently specifically biological problems, we have only to
remember the remarkable progress made by experimental
embryology and the mechanism of development with its
physico-chemical methods. 1 We have another very remark-
able fact in O. Wiener's demonstration of the probable
connexion between color-photography and color-adaptation
in nature. 2 By means of stationary light-waves stratification
may be formed in a medium that is sensitive to light, and
then the incident light may be reflected back as an inter-
ference-color ; but there is yet another way in which a
coloration corresponding to the illumination may arise.
Of materials that are sensitive to light, there are some
which can take on almost any hue. When such materials
are exposed to a colored illumination, they retain the color
of the illumination, because they do not absorb the rays
of the same color as themselves, and consequently the
light is incapable of producing any further change in
1 Cp. W. Roux, Vortrdge und Aufsatze iiber Entivickelungsmechanik
der Organismen, Leipzig, W. Engelmann, 1905.
2 O. Wiener, " Farbenphotographie und Farbenanpassung in der
Natur," Wiedemann's AnnaZen, Vol. LV., 1895, p. 225.
96 THE ANALYSIS OF SENSATIONS
them. According to Poulton's observations l it is probable
that many of the adaptive colors of chrysalises arise in this
manner. Thus in such cases we do not need to look far
afield from the means that produce the effect, in order to
find the " purpose " that is attained. Avoiding all rashness
of statement, we may say that the equilibrium is determined
by the circumstances under which it is attained.
8.
The conceptions of " effective cause " and of " purpose "
both have their origin in animistic views, as is quite clearly
seen from the scientific attitude of antiquity. The savage,
no doubt, does not puzzle his head by reflecting on his own
movements, which seem to him quite spontaneous, natural
and self-evident. But as soon as he perceives unexpected
and striking movements in nature, he instinctively interprets
these movements on the analogy of his own. In this way
the distinction between his own and someone else's volition
begins to dawn upon him. 2 Gradually the similarities and
differences between physical and biological processes stand
1 Poulton, The Colors of Animals, London, 1890.
-I once set a Holtz electrical machine going for the benefit of one of
my boys when he was about three years old. He was delighted by the
dancing sparks. But when I let go the machine and it went on rotating
by itself, he started back in terror and apparently thought it was alive :
"It goes by itself!" he exclaimed, in startled and anxious tones.
Perhaps it is the same with dogs when they run barking after every
moving cart. (For another plausible explanation, which does not
agree with this view, see Zell, Sinddie Tiere unvernunftig? Kosmos-
verlag, p. 38. ) I remember that when I was about three years old I
was frightened when the elastic seed-capsule of a plant of garden-
balsam opened on being pressed, and pinched my finger. It seemed
to me alive, like an animal.
THE ANALYSIS OF SENSATIONS 97
out alternately with ever greater clearness against the back-
ground of the fundamental scheme of volitional action.
Where volitional action is conscious, cause and purpose
still coincide. As regards physical processes, their great
simplicity and their susceptibility to calculation cause the
animistic conception to fade gradually away. Through
a series of rigid forms the conception of cause merges by
degrees into the conceptions of dependence and function.
It is only for the phenomena of organic life, which offer
less resistance to the animistic view, that the conception
of purpose, the notion of an activity that is conscious of its
end, is still maintained ; and where conscious purposive
action cannot be ascribed to the organism itself, some
higher entity that strives towards a goal (Nature, or the
like) is assumed as watching over the organism and guiding
its activities.
Animism, or anthropomorphism, is not an epistomological
fallacy ; if it were, every analogy would be such a fallacy.
The fallacy lies merely in the application of this view to
cases in which the premises for it are lacking or are not
sufficient. Nature, in producing man, has created a pro-
fusion of analogies between lower, and doubtless also
between higher, stages of evolution.
When any process which is completely determined by
the circumstances of the moment, and which remains
limited to itself without further consequences, occurs in
an inorganic, or even in an organic, body, we should
scarcely speak of a purpose, as, for instance, when a
sensation of light or a muscular contraction is excited by
a stimulus. But when the hungry frog snaps at the fly
which it sees, and swallows and digests it, we naturally
98 THE ANALYSIS OF SENSATIONS
adopt the notion of purposive action. Purposiveness only
comes in when the organic functions are resolved into
one another, when they are seen as interconnected, as not
limited to the immediate, as proceeding by way of detours.
In the sphere of the organic a much larger section of the
world-process is manifested ; we are aware of the influence
of a wider spatial and temporal environment. That is why
the organic is more difficult to understand. Real under-
standing is attained when, and only when, we have suc-
ceeded in resolving the complex into its immediately
connected parts. Accordingly, the peculiar characteristics
of the organic must be regarded only as provisional clues.
The perusal of recent biological writings (Driesch, Reinke,
etc.), though perhaps they are opposed to my own
tendencies, only confirms me in this view. And if teleo-
logical investigation can only be provisional, the same is
true of historical investigation also, since all historical
research needs to be supplemented by causal explanation,
a point which is very properly emphasized in Loeb's
biological works, and in K. Menger's writings on economics.
Every organism together with its parts is subject to the
laws of physics. Hence the legitimate attempt gradually
to conceive of an organism as something physical, and to
establish the consideration of it in a "causal" point of
view as alone valid. But whenever we try to do this we
are always brought face to face with the peculiar character-
istics of the organic, for which no analogy can be found in
the physical phenomena of "lifeless" nature, so far as they
THE ANALYSIS OF SENSATIONS 99
have been investigated at present. Every organism is a
system that is able to maintain its peculiar properties, its
chemical composition, its temperature and so forth, in the
face of external influences, and which manifests a state of
dynamic equilibrium of considerable stability. 1 By an
expenditure of energy the organism is able to draw more
energy to itself from its environment, and thus to replace
the loss of energy by an equal or a greater amount. 2 A
steam-engine which should fetch its coal itself and heat
itself, is only a feeble and artificial image of an organism.
The organism possesses these properties even in its minuter
parts ; it regenerates itself from these parts ; that is to say,
it grows and propagates itself. Physics therefore still has
much that is new to learn from a study of the organic
before it is in a position to control the organic. 3
The best physical image of a living process is still
afforded by a conflagration, or some similar process, which
automatically transfers itself to the environment. A con-
flagration keeps itself going, produces its own combustion-
temperature, brings neighbouring bodies up to that tempera-
ture and thereby drags them into the process, assimilates
and grows, expands and propagates itself. Nay, animal
life itself is nothing but combustion in complicated cir-
cumstances .4
10.
Let us compare our volitional action with some reflex
1 Hering, Vorgdnge in der lebendigen Substanz, Lotos, Prague, 1888.
2 Hirth, Energetische Epigenesis, Munich, 1898, pp. x., xi.
3 Hering, Zur Theorie der Nerventatigkeit, Leipzig, 1899.
4 Cf. Ostwald, Naturphilo sophie, and the work of Roux cited on
p. 95, above.
TOO THE ANALYSIS OF SENSATIONS
movement which we have observed in ourselves, and which
causes us surprise when it occurs, or with the reflex move-
ment of an animal. In the two latter cases we can detect
an inclination to regard the whole process as physically
determined by the momentary circumstances of the
organism. Now what we call volition is nothing more
than the totality of those conditions of a movement which
enter partly into consciousness and are connected with a
prevision of the result. If we analyse these conditions, so
far as they enter into consciousness, we find nothing more
than memory-traces of former experiences and their inter-
connection (association). It seems that the preservation
of such traces and their associations is a fundamental
function of elementary organisms, even though, in the case
of such organisms, we are no longer able to speak of
consciousness or of any arrangement in a system of
memories.
If we may take memory and association, in Hering's
wider sense, to be fundamental properties of elementary
organisms, then adaptation would become intelligible. 1
Favourable combinations occur more often than in the
ratio of compound probability, and remain associated.
The presence of food, the feeling of satiety, and swallowing
movements remain interconnected. The fact that phylo-
genesis is repeated in ontogenesis in an abbreviated form,
would constitute a parallel to the well-known phenomenon
by which thoughts return by preference along the paths
which they have once taken, similar thoughts under similar
conditions evoking similar thoughts. We do not indeed
1 Hering, Ueber das Gcdachtnis als allegemeine runktion der organi-
sierten Materie, Vienna, 1870.
THE ANALYSIS OF SENSATIONS 101
know what are the physical counterparts to memory and
association. All the explanations that have been attempted
are very much forced. In this respect it seems as if- there
were almost no analogy between the organic and the in-
organic. It is possible, however, that, in the physiology
of the senses, psychological observation on the one side
and physical observation on the other, may make such
progress that they will ultimately come into contact, and
that in this way new facts may be brought to light. 1 The
result of this investigation will not be a dualism, but rather
a science which, embracing both the organic and the
inorganic, shall interpret the facts that are common to the
two departments.
1 I first tentatively suggested this notion, though still in terms of
Fechner's theories, in the Kompendiiim der Physikfur Mediziner,
1863, p. 234.
VI. THE SPACE SENSATIONS OF
THE EYE.
i.
tree with its hard, rough, grey trunk, its many
-L branches swayed by the wind, its smooth, soft,
shining leaves, appears to us at first a single, indivisible
whole. In like manner, we regard the sweet, round, yellow
fruit, the warm, bright fire, with its manifold moving
tongues, as a single thing. one name designates the
whole, one word draws forth from the depths of oblivion
all the associated memories at once, as if they were strung
upon a single thread.
The reflexion of the tree, the fruit, or the fire in a mirror
is visible, but not tangible. When we turn our glance
away or close our eyes, we can touch the tree, taste the
fruit, feel the fire, but we cannot see them. Thus the
apparently indivisible thing separates into parts, which are
not only attached to one another but also to other condi-
tions. The visible is separable from the tangible, from
that which may be tasted, etc.
What is merely visible also appears at first sight to be a
single thing. But we may see a round, yellow fruit together
with a yellow, star-shaped blossom. A second fruit may be
just as round as the first, but is green or red. Two things
may be alike in color but unlike in form ; they may be
different in color but like in form. Thus sensations of
102
THE ANALYSIS OF SENSATIONS 103
sight are separable into color-sensations and space -sensa-
tions, which are different from one another even though
they cannot be represented in isolation from another.
2.
Color-sensation, into the details of which we shall not
enter here, is essentially a sensation of favorable or un-
favorable chemical conditions of life. In the process of
adaptation to these conditions, color-sensation has probably
been developed and modified. 1 Light introduces organic
1 Compare Grant Allen, The Color-Sense, London, Triibner & Co.,
1879. The attempt of H. Magnus to show a considerable develop-
ment of the color-sense within historical times, cannot, I think, be
regarded as felicitous. Immediately after the appearance of the
writings of Magnus, I corresponded with a philologist, Prof. F. Polle
of Dresden, on this subject, and both of us soon came to the conclusion
that the views of Magnus could not hold their own before the critical
examination either of natural science or of philology. As each of us
left the publication of the results of our discussion to the other, these
were never made public. Meantime, however, the matter has been
disposed of by E. Krause, and in detail by A. Marty. I shall take the
liberty of adding only a few brief remarks. From defects of termin-
ology we cannot infer the absence of corresponding qualities of sensation.
Terms, even to-day, are always indistinct, hazy, defective, and few in
number, where there is no necessity for sharp discrimination. The
color-terminology of the countryman of to-day, and his terminology of
sensations in general, is no more developed than that of the Greek
poets. The peasants of the Marchfeld say, for example, as I have
often proved by personal experience, that salt is "sour," because the
ｅxpression "salty" is not familiar to them. The terminology of
colors must not be looked for in the poets, but in technical works.
And, furthermore, as my colleague Benndorf has remarked, we must
not take an enumeration of vase -pigments for an enumeration of all
colors, as does Magnus. When we consider the polychromy of the
ancient Egyptians and Pompeiians, when we take into account the
fact that these decorations can scarcely have been produced by the
104 THE ANALYSIS OF SENSATIONS
life. The green chlorophyll and the (complementary) red
haemoglobin play a prominent part in the chemical pro-
cesses of the plant-body and in the chemical reactions of
the animal body. The two substances present themselves
to us in the most varied modifications of tint. The dis-
covery of the visual purple, and observations in photography
and photo-chemistry, allow us to conceive visual processes
also as chemical processes. The r61e which color plays in
analytical chemistry, in spectrum-analysis, in crystallography,
is well known. It suggests a new conception for the so-
called vibrations of light, according to which they should
be regarded, not as mechanical, but as chemical vibrations,
as successive union and separation, as an oscillatory process
of the same sort that takes place, though only in one direc-
tion, in photo-chemical phenomena. This conception,
which is substantially supported by recent investigations in
anomalous dispersion, accords with the electro-magnetic
color-blind, when we note that Pompeii was buried in ashes only
seventy years after Vergil's death, whilst Vergil on this theory is sup-
posed to have been nearly color-blind, the untenability of the whole
conception is sufficiently apparent. The question has lately been taken
up again, with recourse to fuller authorities, by W. Schultz (Das
Farbenempjind^lngs system der Hellenen, Leipzig, 1904). Applications
of the Darwinian theory are also to be made with caution in another
direction. We like to picture to ourselves a condition in which the
color-sense is lacking, or in which little color-sense exists, as preceding
another in which the color-sense is highly developed. For the beginner
it is natural to proceed from the simple to the complex. But this is
not necessarily the path of Nature. The color-sense exists, and it is
probably variable. But whether it is being enriched or impoverished
who can tell? Is it not possible that, with the awakening of intelli-
gence and the use of artificial contrivance, the whole development will
be shifted to the intellect, which certainly is chiefly called into play
from this point on, and that the development of the lower organs of
man will be relegated to second place ?
THE ANALYSIS OF SENSATIONS 105
theory of light. In the case of electrolysis, in fact, chemistry
yields the most intelligible conception of the electric current
by regarding the two components of the electrolyte as pass-
ing through each other in opposite directions. It is likely,
therefore, that in a future theory of colors, many biologico-
psychological and chemico-physical threads will be united.
Adaptation to the chemical conditions of life which
manifest themselves in color, renders locomotion necessary
to a far greater extent than adaptation to those which mani-
fest themselves through taste and smell. At least this is so
in the case of man, which is here in question, and as to
which alone a direct and certain judgment is within our
power. The close association of space-sensation (a
mechanical factor) with color-sensation (a chemical factor)
is thus rendered intelligible. We shall now proceed to the
analysis of optical space-sensations.
In examining two figures which are alike but differently
colored (for example, two letters of the same size and shape,
but of different colors), we recognize
their sameness of form at the first glance,
in spite of the difference of color-sensa-
tion. The sight-perceptions, therefore,
must contain some identical sensation-
components. These are the space-sensations which are
the same in the two cases.
IB
io6 THE ANALYSIS OF SENSATIONS
5-
We will now investigate the character of the space-
sensations that physiologically condition the recognition of
a figure. First, it is clear that this recognition is not the
result of geometrical considerations which are a matter,
not of sensation, but of intellect. on the contrary, the
space-sensations in question serve as the starting-point and
foundation of all geometry. Two figures may be geometri-
cally congruent, but physiologically quite different, as is
Fig. 3-
shewn by the two adjoined squares (Fig. 3), which could
never be recognized as the same without mechanical and
intellectual operations. 1 A few simple experi-
ments will render us familiar with the relations
here involved. Look at the spot in Fig. 4.
Place the same spot twice or several times in
exactly the same position in a row (Fig. 5) ; the
result is a peculiar, agreeable impression, and we recog-
nize at once and without difficulty the identity of all the
1 Compare my brief paper, Ueber das Sehen von Lagenund Winkeln,
in the Sitzungsberichte der Wiener Akademie, Vol. XLIIL, 1861, p. 215.
Fig. 4-
THE ANALYSIS OF SENSATIONS 107
Fig. 5-
figures. When, however, we turn one spot far enough
round with respect to the other (Fig. 6), their identity of
form is not recognizable without intellectual
assistance. on the other hand, if we
place two of the spots in positions sym-
metrical to the median plane of the
observer (Fig. 7) the relationship of form
is strikingly apparent. But if the plane
of symmetry diverges considerably from
the median plane of the observer, as in
Fig. 8, the affinity of form is recogniz-
able only by turning the figure around or by an intellectual
act. on the other hand, the affinity of form is
again apparent on contrasting with such a spot
the same spot rotated through an angle of 180
in the same plane (Fig. 9). In this case we have
the so-called centric symmetry.
If we reduce all the dimensions of the spot
proportionately, we obtain a geometrically similar
spot. But as the geometrically congruent is not
necessarily physiologically (optically) congruent, nor
the geometrically symmetrical necessarily optically
symmetrical, analogously the geometrically similar
is not necessarily optically similar. It is only when
the two geometrically similar spots are placed beside Fi - 9-
each other in the same relative positions (Fig. 10), that they
will also appear optically similar. Turning one of the spots
io8 THE ANALYSIS OF SENSATIONS
round destroys the resemblance (Fig. n). If we substitute
for one of the spots a spot symmetrical to the other in
respect of the median plane
of the observer (Fig. 12), a
symmetrical similarity will be
produced which has also an
optical value. The turning
of one of the figures through
1 80 in its own plane, pro-
ducing thereby centrically
symmetrical similarity, has
also a physiologico-optical value (Fig. 13).
6.
In what, now, does the essential nature of optical similarity,
as contrasted with geometrical similarity, consist ? In geo-
metrically similar figures, all homologous distances are
proportional. But that is an affair of the intellect, not of
sensation. If we place beside a triangle with the sides
a, b, , a triangle with the sides 20, 26, 2C, we do not
recognize this simple relation between the two immediately,
but intellectually, by measurement. If the similarity is to
become optically perceptible, the proper position must be
added. That a simple relation of two objects for the
intellect does not necessarily condition a similarity of
sensation, may be perceived by comparing two triangles
having respectively the sides, a, b, c, and a + m,l> + m, + m.
The two triangles do not look at all alike. Similarly all
conic sections do not look alike, although all stand in a
simple geometric relation to each other ; still less do curves
of the third order exhibit optical similarity, etc.
THE ANALYSIS OF SENSATIONS 109
The geometrical similarity of two figures is determined
by all their homologous lines being proportional or by all
their homologous angles being equal. But to appear optically
similar the figures must also
be similarly situated^ that is
all their homologous direc-
tions must be parallel or, as
we prefer to say, must be the
same (Fig. 14). The import-
ance of direction for sensation will be evident upon a careful
consideration of Fig. 3. It is by identity of direction,
accordingly, that are determined the identical space-sensa-
tions which are characteristic of the physiologico-optical
similarity of the figures. 1
We may obtain an idea of the physiological significance
of the direction of a given straight line or curve-element,
by the following reflexion. Let y^=f(x) be the equation
of a plane curve. We can read at a glance the course of
the values of dy\dx on the curve, for they are determined
1 Some forty years ago, in a society of physicists and physiologists, I
proposed for discussion the question, why geometrically similar figures
were also optically similar. I remember quite well the attitude taken
with regard to this question, which was accounted not only superfluous,
but even ludicrous. Nevertheless, I am now as strongly convinced as
I was then that this question involves the whole problem of form-vision.
That a problem cannot be solved which is not recognized as such is
clear. In this non-recognition, however, is manifested, in my opinion,
that one-sided mathematico-physical direction of thought, which alone
accounts for the opposition, from so many sides and extending over so
many years, instead of cheerful acceptance, with which the writings of
Hering have been received-
no THE ANALYSIS OF SENSATIONS
by its steepness ; and the eye gives us, likewise, qualitative
information concerning the values of d 2 yjdx 2 t for they are
characterized by the curvature. The question naturally
presents itself, why can we not arrive at as immediate
conclusions concerning the values d 3 y/dx 3 , d 4 y/dx\ etc.
The answer is easy. What we see is of course not the
differential coefficients, which are an intellectual affair, but
only the direction of the curve-elements, and the deviation
of the direction of one curve-element from that of another.
In fine, since we are immediately cognisant of the
similarity of figures lying in similar positions, and are also
able to distinguish at once the special case of congruity,
therefore our space-sensations yield us information con-
cerning identity or difference of directions and equality or
inequality of dimensions.
8.
It is a priori extremely probable that sensations of space
are connected in some way with the motor apparatus of
the eye. Without entering into particulars, we may observe,
first, that the whole apparatus of the eye, and especially the
motor apparatus, is symmetrical with respect to the median
plane of the head. Hence, symmetrical movements of
looking will be connected with like or approximately like
space-sensations. Children constantly confound the letters
b and d, p and q. Adults, too, do not readily notice a
change from left to right, unless some special points of
apprehension for sensev or intellect make it noticeable.
The symmetry of the motor apparatus of the eye is very
perfect. The like excitation of its symmetrical organs
would, by itself, scarcely account for the distinction of
THE ANALYSIS OF SENSATIONS in
right and left. But the whole human body, especially the
brain, is affected with a slight asymmetry, which leads,
for example, to the preference of one (generally the right)
hand, in motor functions. And this leads, again, to a
further and better development of the motor functions of
the right side, and to a modification of the attendant
sensations. After the space-sensations of the eye have
become associated, through writing, with the motor sensa-
tions of the right hand, a confusion of those vertically
symmetrical figures with which the art and habit of writing
are concerned no longer ensues. This association may
even become so strong that the memories follow only the
accustomed tracks, and we read, for example, the reflexion
of written words in a mirror only with the greatest difficulty.
The confusion of right and left still occurs, however, with
regard to figures which have no motor, but only a purely
optical (for example, ornamental) interest. A noticeable
difference between right and left must be felt, moreover,
by animals, as in many predicaments they have no other
means of finding their way. How similar, moreover, are
the sensations connected with symmetrical motor functions
is easily remarked by the attentive observer. If, for
example, because my right hand happens to be engaged,
I grasp a micrometer-screw or a key with my left hand,
I am certain (unless I reflect beforehand) to turn it in
the wrong direction, that is, I always perform the move-
ment which is symmetrical to the usual movement, con-
fusing the two because of the similarity of the sensation.
The observations of Heidenhain regarding the reflected
writing of persons hypnotized on one side should also be
cited in this connexion.
H2 THE ANALYSIS OF SENSATIONS
The idea that the distinction between right and left
depends upon an asymmetry, and possibly in the last
resort upon a chemical difference, is one which has been
present to me from my earliest years. I gave ｅxpression
to it in the first lectures I ever delivered, in 1861. Since
then this idea has forced itself upon me again and again.
I learned by chance from a retired army-officer that on dark
nights or in snow-storms, when external landmarks are
absent, troops will move approximately in a circle of large
radius so that they almost return to their point of departure,
though all the time they are under the impression that
they are marching straight forward. An analogous pheno-
menon is narrated in Tolstoi's story, Master and Servant.
Probably the only way to understand these phenomena is
to assume a slight motor asymmetry. They are analogous
to the way in which a ball with a slight deviation from
the true cylindrical shape rolls in a circle of large radius.
This is actually the way in which the matter is regarded
by F. O. Guldberg, 1 who has carried out detailed researches
on the phenomena presented in this connexion by human
beings and animals that have lost their way. Human
beings and animals that have lost their direction move,
almost without exception, nearly in circles, of which the
radii vary according to the species, while the centre lies
sometimes on the left hand of the individual travelling
along the circumference, and sometimes on his right,
1 F. O. Guldberg, " Die Zirkularbewegung," Zeitschrift far Biologic,
Vol. XXV., p. 419, 1897. Dr W. Pauli drew my attention to this
article in conversation.
THE ANALYSIS OF SENSATIONS 113
according to the individual and the species. According
to Guldberg we have here a teleological device to help
parents to find their hungry young again when they have
been lost. Experiments on the lower animals, with whom
this factor is absent, would therefore be interesting. For
the fest, we should expect, on grounds of general proba-
bility, to find imperfect symmetry in the lower animals also.
Again, Loeb's researches " on the Spatial Feeling of
the Hand," J have taught us, amongst other things, that
when the eyes are bandaged, a given movement of the
right hand, if imitated by the left, is always reproduced
in an exaggerated or a diminished form ; the degree of
exaggeration or diminution varying with the individual.
Loeb thinks that the phenomena of regeneration allow us
to infer that the distinction between right and left is
specific. I am certain, however, that I personally have
never regarded it as a merely geometrical and quantitative
motor difference.
10.
With looking upwards and looking downwards, funda-
mentally different space - sensations are associated, as
ordinary experience shows. This is, moreover, compre-
hensible, since the motor apparatus of the eye is asym-
metrical with respect to a horizontal plane. The direction
of gravity also is so very decisive and important for the
motor apparatus of the rest of the body that this fact has
assuredly also found its ｅxpression in the apparatus of the
eye, which serves the rest. It is well known that the
1 Loeb, " Ueber den Ftihlraum der Hand," Pflliger's Archiv, Vols,
XLI. and XLVI.
H
H4 THE ANALYSIS OF SENSATIONS
symmetry of a landscape and of its reflexion in water is
not felt. The portrait of a familiar personage, when turned
upside down, is strange aid puzzling to a person who
does not recognize it intellectually. If we place ourselves
behind the head of a person lying upon a couch, and
unreflectingly give ourselves up to the impression which
the face makes upon us, we shall find that our impression
is altogether strange, especially when the person speaks.
The letters b and /, and d and ^, are not confused even
by children.
Our previous remarks concerning symmetry, similarity,
and the rest, naturally apply not only to plane figures, but
also to those in space. Hence, we have yet a remark to
add concerning the sensation of space-depth. The sight
of something at a distance causes different sensations from
the sight of something near at hand. These sensations
must not be confused, because of the supreme importance
of the difference between near and far, both for animals and
human beings. They cannot be confused, because the
motor apparatus is asymmetrical with respect to a plane
perpendicular to the direction from front to rear. It is a
common experience that a portrait-bust of a person whom
we know quite well cannot be replaced by the mould
in which the bust is cast, and this experience is quite
analogous to the observations consequent upon the inver-
sion of objects.
ii.
If we suppose that identical dimensions and identical
directions excite identical space-sensations, and that direc-
tions symmetrical with respect to the median plane of the
THE ANALYSIS OF SENSATIONS 115
head excite similar space-sensations, it becomes easy to
understand the above-mentioned facts. The straight line
has, in all its elements, the same direction, and everywhere
excites the same space-sensations. Herein consists its
aesthetic value. Moreover, straight lines which lie in the
median plane or are perpendicular to it are brought into
special relief by the circumstance that, thanks to this
position of symmetry, they stand in the same relation to
both of the two halves of the visual apparatus. Every other
position of the straight line is felt as an obliquity, as a
deviation from the position of symmetry.
The repetition of the same space-figure in the same posi-
tion conditions a repetition of the same space-sensation.
All lines connecting prominent (noticeable) homologous
points have the same direction and excite the same sensa-
tion. Likewise when merely geometrically similar figures
are placed side by side in the same positions, this relation
holds. The sameness of the dimensions alone is absent.
But when the positions are disturbed, this relation, and
with it, the impression of unity the aesthetic impression
are also disturbed.
In a figure symmetrical with respect to the median plane,
similar space-sensations corresponding to the symmetrical
directions take the place of the identical space-sensations.
The right half of the figure stands in the same relation to
the right half of the visual apparatus as the left half of
the figure does to the left half of the visual apparatus.
If we alter the sameness of the dimensions, the sensa-
tion of symmetrical similarity is still felt. An oblique
position of the plane of symmetry upsets the whole
relation.
n6 THE ANALYSIS OF SENSATIONS
If we turn a figure through 180, contrasting it with
itself in its original position, centric symmetry is produced.
That is, if two pairs of homologous points be connected,
the connecting lines will cut each other at a point <9,
through which, as their point of bisection, all lines connect-
ing homologous points will pass. Moreover, in the case
of centric symmetry, all lines of connexion between homo-
logous points have the same direction, a fact which
produces an agreeable sensation. If the sameness of the
dimensions is eliminated, there still remains, for sensation,
centrically symmetrical similarity.
Regularity appears to have no special physiological value,
in distinction from symmetry. The value of regularity
probably lies only in its manifold symmetry, which is
perceptible in more than one single position.
12.
The correctness of these observations will be apparent
on glancing over the work of Owen Jones A Grammar of
Ornament^ London, 1865. In almost every plate one
finds new and different kinds of symmetry as fresh testi-
mony in favor of the conceptions above advanced. The
art of decoration, which, like pure instrumental music, aims
at no ulterior end, but ministers only to pleasure in form
and color, is the best source of material for our present
studies. Writing is governed by other considerations than
that of beauty. Nevertheless, we find among the twenty-
four large Latin letters ten which are vertically symmetrical
(A, H, I, M, O, T, V, W, X, Y), five which are horizon-
tally symmetrical (B, C, D, E, K), three which are centri-
THE ANALYSIS OF SENSATIONS 117
cally symmetrical (N, S, Z), and only six which are
unsymmetrical (F, G, L, P, Q, R).
The study of the evolution of primitive art is extremely
instructive in connexion with the problems under discussion.
The character of primitive art is determined, firstly, by
the natural objects that offer themselves to the imitation
of the artist j secondly, by the degree of mechanical skill
attained ; and finally by the effort to make use of repetition
in its various forms. 1
I have clearly explained briefly in previous writings the
aesthetic significance of the above-mentioned facts, to treat
of which in detail was not part of my plan. I cannot, how-
ever, refrain from mentioning that this has been done by a
physicist, the late J. L. Soret of Geneva, in an admirable
book published in 1892,2 for which the way was prepared
by a lecture delivered by him at the meeting of the Swiss
Scientific Association in 1866. Soret's views are connected
with those of Helmholtz, and he does not seem to be
acquainted with my theories. He does not go into the
physiological side of the question, but on the aesthetic side
his exposition is very copious and illustrated by appropriate
examples. He discusses the aesthetic effect of symmetry, of
repetition, of similarity and of continuity, which last he
regards as a special case of repetition. According to him
slight deviations from symmetry can more than compensate
1 Alfred C. Haddon, Evolution in Art, as illustrated by the Life-
histories of Designs ; London, 1895.
2 J. L. Soret, Sur les conditions physiques de la perception du bcatt,
Geneva, 1892.
n8 THE ANALYSIS OF SENSATIONS
for the loss in sensual satisfaction by the multiplicity which
they introduce and by the intellectual aesthetic pleasure
bound up with that multiplicity. This is illustrated from
the sculptured ornaments of Gothic cathedrals. This
intellectual pleasure is also produced by the virtual or
potential symmetry which we perceive when the human
figure or some other symmetrical form is placed in an
asymmetrical position. And he does not merely apply
these reflexions to optical cases, but extends them to all
departments, as also has been done by me. He notices
rhythm, music, movements, dancing, the beauties of Nature,
and even literature. Particularly interesting are his
observations on blind people, which the Asylum for the
Blind at Lausanne gave him the opportunity of carrying out.
Blind people take pleasure in the periodic repetition of the
same forms in tangible objects, and have a decided sense
of formal symmetry. Striking disturbances in symmetry of
form are unpleasant to them, and sometimes even seem to
them ludicrous. A blind man, who had been accustomed
to study a large-scale map of Europe in relief, recognized
that continent by means of geometrical similarity when he
found it as part of a larger raised map on a smaller scale.
The symmetrical organs of touch, the two arms and hands,
are in fact arranged in an analogous way to the organs of
sight, so that we need not be surprised at the agreement.
Even in antiquity this agreement was not without its
influence upon inquirers, to say nothing of a modern
thinker like Descartes; it even produced a number of
unfortunate notions which are partly operative even to-day.
Soret's chapter on literature seems less successful. True,
in metre, rhyme, etc., we have phenomena similar to those
THE ANALYSIS OF SENSATIONS 119
noticed in the previously treated departments. But when,
for example, he draws a parallel between the effect of the
sixfold repetition of the phrase " Que diable allait il faire
dans cette galere," in Moliere's well-known play, 1 and the
repetition of an ornamental motive, probably few will agree
with him. It is certain that the effect of this repetition is
not produced by the repetition as such, but by the succes-
sive heightening of a comic contrast, and that consequently
it is merely intellectual.
Finally, I should like to draw the attention of the reader
to an article by Arnold Emch in The Monist for October,
1900, on "Mathematical Principles of ^Esthetic Forms."
Emch gives attractive examples of the way in which a
number of forms arranged in a series co-operate to produce
an aesthetic impression by observing one and the same
geometrical principle. He is following out the line of
thought on which I touched in my lecture of 1871, accord-
ing to which production in accordance with a fixed rule
has an aesthetic effect (Popular Scientific Lectures, Chicago,
Open Court Publishing Co., 1894). But in that place I
laid stress upon the point, and should like to do so again,
that the rule, considered as an affair of the intellect, has no
aesthetic effect in itself, but that the effect depends on the
repetition, determined by the rule, of one and the same
sensational motive.
14.
Here we must once more point out that the geometrical
and. the physiological properties of a figure in space are to be
1 Les Fotirberies de Scapin.
120 THE ANALYSIS OF SENSATIONS
sharply distinguished. The physiological properties are
determined by the geometrical properties coincidently with
these, but are not determined by these solely. on the
other hand, physiological properties very probably gave
the first impulse to geometrical investigations. The
straight line doubtless first attracted attention not because
of its being the shortest line between two points, but
because of its physiological simplicity. The plane likewise
possesses, in addition to its geometrical properties, a special
physiologico-optical (aesthetic) value, which causes it to be
noticed, as will be shown later on. The division of the
plane and of space by right angles has not only the
advantage of producing equal parts, but also an additional
and special symmetry-value. The circumstance that
congruent and similar geometrical figures can be brought
into positions where their relationship is physiologically
felt, led, no doubt, to an earlier investigation of these
kinds of geometrical relationship than of those that are less
noticeable, such as affinity, collineation, and others. With-
out the co-operation of sense-perception and understanding,
'a scientific geometry is inconceivable. But H. Hankel
has admirably shewn in his History of Mathematics (Leipzig,
1874) that in Greek geometry the factor of pure under-
standing is decidedly dominant, whereas in Indian geometry
the factor of sense has the upper hand. The Hindus
make use of the principles of symmetry and similarity (see,
for example, p. 206 of Hankel's book) with a generality
which is totally foreign to the Greeks. Hankel's proposal
to unite the rigor of the Greek method with the perspicuity
of the Indian in a new mode of presentation is well worthy
of encouragement. Furthermore, in so doing, we should
THE ANALYSIS OF SENSATIONS 121
only be following in the footsteps of Newton and John
Bernoulli, who, even in mechanics, applied the principle of
similarity in a still more general manner. The advantages
that the principle of symmetry affords in the last-named
department, I have shown at length elsewhere. 1
1 I have given less complete discussions of the leading thoughts of
this chapter in the paper already mentioned, Ueberdas Sehen von Lagen
und Winkeln (1861), further (in Fichte's Zeitschrift fur Philosophic,
Vol. XLVL, 1865, p. 5, and in The Forms of Liquids, and Symmetry
(1872) now also published in my Popular Scientific Lectures, translated
by Thomas J. McCormack, Open Court Publishing Co., Chicago, 1894.
With regard to the use of the principle of symmetry in mechanics,
compare my work The Science of Mechanics (1883), translated by
Thomas J. McCormack, 1893, Open Court Pub. Co., Chicago.
VII. FURTHER INVESTIGATION OF
SPACE-SENSATIONS. 1
i.
OUR knowledge of spatial vision made important
advances in the course of the nineteenth century, not
merely because a gain in positive understanding was
involved, but also because the prejudices accumulated
by various philosophers and physicists in this department,
especially since Descartes, have been finally disposed of,
and thereby that freedom from preconceptions attained
which is the first requisite for making positive discoveries.
Johannes Miiller, 2 created the doctrine of specific
energies, and also put forward with great lucidity the
theory of identical retinal positions, which, for the rest,
can be clearly traced back as far as Ptolemy. 3 on Miiller's
1 So far as I know, the matter treated in the preceding chapter has
not yet been discussed, except in three small works of my own, and in
Soret's book. The considerations of the present chapter, moreover,
are, for me, founded upon those of the preceding chapter. I indicate
here the methods by which I have myself reached clear ideas as to the
sensation of space, without laying the least claim to that which has
been accomplished by others in this direction, particularly by the theory
of Hering. The extensive literature of this subject is, moreover, too
imperfectly known to me for me to give exact references on all points.
The point of Hering's theory which I regard as the most important I
will especially notice.
2 J. Miiller, Vergleichende Physiologic des Gesichtsinnes, 1826;
Handbuch der Physiologic, Vol., II., 1840.
3 L'Ottica di Claudio Tolomeo, published by G. Govi, Turin, 1885.
122
THE ANALYSIS OF SENSATIONS 123
theory that the retina has sensations of itself in its own
activity, "visual space" is, for him, something immediately
given. My own body also appears in my field of vision.
All questions of direction can only refer to the relative
positions of parts of the field of vision. The direc-
tion of vision depends exclusively on the arrangement
of the sensitive parts of the retina. All theories as to
projection, and problems as to why we see things upright,
disappear. But estimation of the distance of an object
seen is, for Miiller, still through and through an affair of
the intellect.
Wheatstone's 1 discovery of the spectroscope led at once
to the conviction that in certain circumstances images
could be seen as simple, and with different degrees of depth
according to the stereoscopic difference, not only when the
images fell upon identical parts of the retina, but also when
they fell upon other parts, provided the difference between
the parts was not too great. The result of this was to throw
doubt on the doctrine of identity, and to stimulate the
formulation of psychological explanations of how we come
to see things as having depth. Hence arose Briicke's
theory of successive fixation in spatial vision, which in its
turn was proved to be untenable by Dove's experiments in
instantaneous illumination with the stereoscope.
Panum 2 opposed these theories with arguments of great
force, and by admirably contrived experiments. Taking his
stand on the phenomenon of binocular rivalry and the
prominent part played therein by contours, he came to the
1 Wheatstone, " Contributions to the Theory of Vision," Philosophical
Transactions 1838, 1852.
2 Panum, Untersuchungen liber das Sehen mit zwei Augen, 1858.
124 THE ANALYSIS OF SENSATIONS
conclusion that our seeing things as having depth depends
upon a reciprocal action, or " Synergy/' of the two retinae,
and that the sensation of depth is an innate specific energy.
The more similar the two monocular images, and especially
the contours, are in form, color, and position, the more
easily do they coalesce into a single binocular image, of
which the depth is determined by the stereoscopic
difference. But Panum still maintains that this depth
corresponds to what is given by means of lines of
projection.
It is to Hering * that we owe the most thorough clearing
away of old prejudices. His starting-point is the view that
our immediately given visual space must be completely dis-
tinguished from the conceptual space which we obtain by
means of experiences of a special kind. He proves by
decisive experiments that the direction in which we see an
object is different from the line, the line of vision, or of
projection,- between the object and the retinal image.
There are two lines of vision, one for each eye ; but there
is only one direction of vision, bisecting the angle formed
by these two lines. We have to think of this direction of
vision as proceeding from the point of bisection of the
line connecting the two eyes. In order to exclude all
reference to geometrical space, we may put it thus : The
two eyes together see the same relative horizontal and
perpendicular arrangements that a single eye would see
if it were situated half-way between the two eyes. Suppose
that, looking in a horizontal direction and with symmetrical
1 Hering, Beitrdge zur Physiologic, 1861-1865 ; Archivfar Anatomie
und Physiologic, 1864, 1865 ; " Der Raumsinn und die Bewegungen des
Auges," in Hermann's Handbuch der Physiologic, Vol. III., I, 1879.
THE ANALYSIS OF SENSATIONS 125
convergence, we fix our gaze upon a point on the window-
pane ; then we see this point in the median plane, but at
the same time we see behind it in the same plane objects
lying a long way to one side. In the stereoptical experi-
ment we still see objects in front of us, even when there is
only a slight divergence of the axes of the eyes, although the
directions of projection no longer lead to these objects, or
at any rate have no longer any physical or physiological
meaning. Again, the distances which we see do not agree
with the results of the theory of projection. When, with
horizontal lines of vision, we stretch vertical threads through
Miiller's circular horopter, the cylinder thereby produced
appears to us like a plane. We see not only the image of
the fixed or "nucleus" point, but also the collective con-
ception of all the points (the " nucleus-surface ") represented
in identical, or "corresponding," positions, as a plane lying
before us at a definite distance. It is impossible to explain
these and many other analogous facts on the theory of
projection. Hering reduces spatial vision to a simple
principle. Identical, or "corresponding," points on the
retina have identical height and breadth-values ; symmetri-
cal points on the retina, on the other hand, have identical
depth-values, and these last increase from the outer edges
of the retina inwards. When similarity of the monocular
images in color, shape and position causes them to coalesce
into a singular binocular image, the binocular image con-
tains the mean value of the depth-values of the single
images. Such mean values of the single images play a
decisive part in general, and in particular as regards the
directions of vision. These indications must be sufficient
for us here, since we cannot now discuss in detail the varied
126 THE ANALYSIS OF SENSATIONS
contents of the works in which Hering has laid the secure
foundations on which this chapter is based. 1 The only
further remark I will make is, that, according to him, the
two eyes are to be conceived as a single united organ, the
associated movements of which rest on an innate anatomical
foundation, a point that had already been brought out
by Johannes Miiller.
Biological and psychological 2 research combine to con-
firm the conclusion that, as regards the intuition of
space, the nativistic view can a fortiori be maintained.
The chick has scarcely broken from its shell than it is
seen to be at home in space and pecking at everything
that excites its attention. For the new-born human being
we can at most suppose only a lower degree of maturity,
but otherwise the conditions must be essentially the same.
Panum has brought out this point. Spatial intuition
is therefore present at birth. Whether we shall ever be
in a position to explain it, in the sort of way attempted
by Helmholtz, by means of the history of evolution or the
history of the race, is a separate question.
Perhaps clues towards the solution of this problem
may be found in the facts of phylogenetic develop-
ment and the variation of retinal correspondence
(investigated by Johannes Miiller 3 ) which takes place
at the transition between one animal species and
another. Another promising field for research is pre-
1 Among the works of younger investigators connected with Hering's
researches, those of F. Hillebrand are of particular interest for
psychology.
2 Stumpf Der psychologische Urspwng der Raumvorstellungen, 1873.
3 Vergleichende Physiologic des Gesichtssinnes, pp. 106, sqq.
THE ANALYSIS OF SENSATIONS 127
sented by the pathological anomalies of people who
squint and the phenomena of adaptation to be observed
in these cases. 1
2.
That space-sensation is connected with motor processes
has long since ceased to be disputed. Opinions differ only
as to how this connexion is to be understood.
If two congruent images of different colors fall in
succession on the same parts of the retina, they are at once
recognized as identical figures. We may, therefore, regard
different space-sensations as connected with different parts
of the retina. But that these space-sensations are not
unalterably connected with particular parts of the retina,
we perceive on moving our eyes freely and voluntarily,
whereby the objects observed do not change their position
or form, although their images are displaced on the retina.
If I look straight before me, fixing my eyes upon an
object O, an object A, which is re-
flected on the retina in a, at a certain
distance below the point of most
distinct vision, appears to me to be
situated at a certain height. If I
, . Fig. 15-
now raise my eyes, fixing them upon
B, A retains its former height. It would necessarily appear
1 Tschermak, ' * Ueber anomale Sehrichtungsgemeinschaft der
Netzhaute bei Schielenden," Graefe's Archiv, XLVIL, 3, p. 508 ;
Tschermak, Ueber physiologische und pathologischc Anpass^^ng des
Auges, Leipzig, 1900; Schlodtmann, " Studien iiber anomale
Sehrichtungsgemeinschaft bei Schielenden," Graefe's Archiv,
LI-, 2, 1900.
128 THE ANALYSIS OF SENSATIONS
lower down if the position of the image on the retina, or the
arc 0a, alone determined the space-sensation. I can raise my
glance as far as A and farther without any change in this
relation. Thus, the physiological process which conditions
the voluntary raising of the eye, can entirely or partly take
the place of the height-sensation, is homogeneous with it,
or, in brief, algebraically summable with it. If I turn my
eyeball upward by a slight pressure of the finger, the
object A actually appears to sink, proportionately to the
shortening of the arc oa. The same thing happens when,
by any other unconscious or involuntary process for
example, through a cramp of the muscles of the eye the
eyeball is turned upward. According to an experience now
familiar to oculists for some decades patients with paralysis
of the rectus externus reach too far to the right in attempt-
ing to grasp objects at the right. Since they need to exert
a stronger impulse of the will than persons of sound eyes,
in order to fix their glance upon an object to the right,
the thought naturally suggests itself that the will to look
to the right determines the optical space-sensation "right."
Some years ago, 1 I put this observation into the form of
an experiment, which every one can try for himself. Let
the eyes be turned as Jar as possible towards the left and
two large lumps of moderately hard putty firmly pressed
against the right side of each eye-ball. If, now, we attempt
to glance quickly to the right, we shall succeed only very
imperfectly, owing to the imperfectly spherical form of the
eyes, and the objects will suffer a strong displacement to
the right. Thus the mere will to look to the right imparts
1 Shortly after finishing my Grundlinien der Lehre von den Beweg-
ungsempfindungen (1875).
THE ANALYSIS OF SENSATIONS 129
to the images at certain points of the retina a larger " right-
ward value," as we may term it for brevity. The experiment
is, at first, surprising. It will soon be perceived, however, that
both facts viz., that by voluntarily turning the eyes to the
right, objects are not displaced, and that by the forced, in-
voluntary turning of the eyes to the left, objects are displaced
to the right together teach the same lesson. My eye, which
I wish to, and cannot, turn to the right, may be regarded as
voluntarily turned to the right and compulsorily turned back
by an external force. Professor W. James l could not get
the experiment just mentioned to succeed. I have often re-
peated it, and always found it confirmed. I think that the
fact is certain, but of course that decides nothing as to its
correct interpretation.
3-
The will to perform movements of the eyes, or the
innervation to the act, is itself the space-sensation. This
follows naturally from the preceding consideration. 2 If we
have a sensation of itching or pricking in a certain spot of
our skin, by which our attention is sufficiently secured, we
immediately grasp at the spot with the correct amount of
movement. In the same manner we turn our eyes with
the correct amount of exertion towards an object reflected
on the retina, as soon as this exerts a sufficient stimulus to
draw our attention. By virtue of organic arrangements
and long exercise we hit immediately upon the exact
1 W. James, The Principles of Psychology, II., p. 509.
2 1 retain the ｅxpression which first immediately suggested itself to
me (1875), with no intention of forestalling future inquiry. Here and in
what follows I leave it an open question whether innervation is a con-
sequence of space-sensation, or vice versa. They are certainly closely
connected.
130 THE ANALYSIS OF SENSATIONS
degree of innervation sufficient to enable us to fix our
eyes upon an object reflected on a certain point of the
retina. If the eyes are already turned towards the right,
and we begin to give our attention to an object further to
the right or the left, a new innervation of the same sort is
algebraically added to that already present. A disturbance
of the process arises only when alien, involuntary innerva-
tions or externally moving forces are added to the innerva-
tions determined by the will.
Years ago, while occupied with the questions now under
discussion, I noticed a peculiar phenomenon, which has
not yet, so far as I know,
been described. In a
very dark room we fix
our eyes upon a light
A, and then suddenly
look at a light lower
down, B. At this, the
light A appears to make
a rapid sweep A A'
(quickly ended) up-
wards. The light B, of course, does the same ; but to avoid
complications, this is not indicated in the diagram. The
sweep is, of course, an after-image, which enters conscious-
ness only on completion, or shortly before completion, of the
glance-movement, but and this is the remarkable point
with positional values that correspond, not to the later,
but to the earlier innervations and position of the eye.
Similar phenomena are often noticed in experiments with
THE ANALYSIS OF SENSATIONS 131
Holtz's electrical machine. If the experimenter is surprised
by a spark during a glance downwards, the spark often
appears high above the electrodes. If it yields a lasting
after-image, the image appears, of course, below the
electrodes. The preceding phenomena answer to the so-
called personal equation of astronomers, except that they
are confined to the province of sight. By what organic
arrangements this relation is determined must be left an
open question, but it is probably of some value in pre-
venting confusion of position in movements of the eyes. 1
For the sake of simplicity we have hitherto regarded
only the eyes as in motion, and have considered the head
and the body generally as at rest. If, now, we move the
head about without intentionally fixing the eyes upon any
object, the objects seen remain motionless. But at the
same time another observer may notice that the eyes, like
frictionless, inert masses, take no
part in the turning movements.
Still more noticeable is the pheno.
menon if we turn with continuous
motion, actively or passively, about a
vertical axis, as viewed from above,
say, in the direction of the hands of a clock. In this case, as
Breuer has observed, the open or closed eyes turn, about
ten times to a full revolution of the body, in the opposite
direction to that of the clock-hands, with a uniform
motion, and as frequently back again in the opposite
1 For a different explanation see Lipps, Zcitschrift fur Psychologic
Tind Physiologic der Sinnesorgane^ Vol. I., p. 60.
132 THE ANALYSIS OF SENSATIONS
direction by jerks. The process is represented in the
diagram of Fig. 17. on O T, the times are laid off as
abscissae, the angles described in the direction of the
clock-hands are laid off as ordinates upwards, and the
angles described in the opposite direction as ordinates
downwards. Tne curve OA corresponds to the rotation
of the body, O B B to the relative, and O C C to the
absolute, rotation of the eyes. No one, on repeating the
experiment, can avoid the conclusion that we are concerned
here with an automatic (unconscious) movement of the
eyes, reflexively excited by the rotation of the body. This
movement disappears as soon as the passive rotation is no
longer felt. How it is brought about remains, naturally, to
be investigated. A simple way of looking at it would be that
there are two antagonistic organs of innervation, and that the
stimulus which reaches them both uniformly when the body
rotates, is answered by one with a uniform stream of
innervation, while the other delivers its impulse of innerva-
tion only after the lapse of a certain time, like a rain-gauge
suddenly tipping up when it is full. For us it suffices,
provisionally, to know that this automatic, unconscious
compensational movement of the eye is actually present.
The compensational wheel-like movement of the eyes,
which takes place when the head is inclined to one side, is
well-known. Nagel * has proved that it amounts to from
one-tenth to one-sixth of the angle of inclination of the
head. And recently Breuer and Kreidl 2 have made similar
1 Nagel, " Ueber Kompensatorische Raddrehungen der Augen," Zeit-
schriftfurPsychologieundPhysiologie der Sinnesorgane, Vol. XII. , p. 338.
2 Breuer and Kreidl, " Ueber scheinbare Drehung des Gesichtsfeldes
wahrend der Einwirkung einer Zentrifugalkraft," Pfltiger's Archiv,
Vol. LXX., p. 494-
THE ANALYSIS OF SENSATIONS 133
experiments in the rotatory apparatus also, with the follow-
ing results :
" We have a sensation, as Purkynie and Mach have
maintained, of the direction of the acceleration of masses.
When this direction is changed by the interference of a
horizontal acceleration affecting the body on one side, a
wheel-like movement of the eyes is set up and persists as
long as the interference lasts. It amounts to 0-5 or o'6 of
the angle of deviation. The rotation of visual space, and
the appearance of vertical lines as oblique, which takes
place under such conditions, depend therefore on an actual
but unconscious rotation of the eyes."
I must also mention here two papers by Crum Browne J
on compensating movements of the eyes.
6.
The slower unconscious compensating movement of the
eye (the jerking movement leaves behind it no optical
impression) is thus the reason why, when the head is turned,
objects seem to retain their position a fact which is very
important for orientation. If, now, in turning our head, we
also voluntarily turn the eyes in the same direction, fixing
them upon one object after another, we must overcompen-
sate the automatic, involuntary innervation by the voluntary
innervation. We need the same innervation as if the whole
angle turned through were described by the eye alone. In
1 Crum Brown, " Note on Normal Nystagmus/* Proc. of the Royal
Society of Edinburgh, 4th Feb. 1895: "The Relation between the
Movements of the Eye and the Movements of the Head," Robert Boyle
Lechtre, I3th May 1895.
134 THE ANALYSIS OF SENSATIONS
this way is explained why, when we turn about, the whole
optical space appears to us a continuum and not an aggre-
gation of fields of vision ; and why, at the same time, the
optical objects remain stationary. That which we see of
our own body, in turning, we see, for obvious reasons,
optically in motion.
Thus we arrive at the practically valuable conception of
our body as in motion in a fixed space. We understand
why it is that, in our numerous turnings and ramblings in
the streets and in buildings, and in our passive turnings in
a wagon or in the cabin of a ship, even in the dark, we do
not lose our sense of direction, though it is true that the
primary co-ordinates from which we started gradually sink
unnoticed into unconsciousness, and we soon begin to reckon
from new objects around us. That peculiar state of con-
fusion as to locality in which we sometimes find ourselves
on suddenly awaking at night, where we look about help-
lessly for the window or the table, is probably due to dreams
of movement immediately preceding our awaking.
Similar phenomena to those which manifest themselves on
the rotation of the body make their appearance in connexion
with the movements of the body generally. If I move my
head or my whole body sidewise, I do not lose sight of an
object on which my eyes rest. The latter seems to continue
motionless, while the more distant objects undergo a dis-
placement in the same direction as that of the body, and nearer
objects a parallactic displacement in the opposite direction.
The parallactic displacements to which we are accustomed are
perceived, but do not cause us any disturbance and are cor-
rectly interpreted. But in the monocular inversion of a Plateau
wire -net, the parallactic displacements, which in the present
THE ANALYSIS OF SENSATIONS 135
case are unusual as regards amount and direction, immediately
attract the eye, and apparently present to us a revolving object. 1
7-
When I turn my head, I not only see that part of it turn-
ing which I am able to see (as will be immediately under-
stood from the foregoing) but I also feel it turning. This is
due to the fact that conditions exist in the province of touch
which are entirely analogous to those in the province of sight. 2
'Compare my " Beobachtungen liber monoculare Stereoscopic,"
Sitzungsberichte der Wiener Akademie, Vol. LVIII., 1868.
2 The view that the sense of sight and the sense of touch involve, so
to speak, the same space-sense as a common element, was advanced
by Locke and contested by Berkeley. Diderot also (Lettres sur les
aveugles) is of opinion that the space-sense of the blind is altogether
different from that of a person who sees. Compare on this point the
acute remarks of Dr. Th. Loewy ( Common Sensibles. Die Gemeinideen
des Gesichts- und Tastsinnes nach Locke und Berkeley, Leipzig, 1884),
with whose results, however, I cannot agree. The circumstance that
a man blind from birth does not, after being operated upon, in accord-
ance with the experiment proposed by Molyneux, visually distinguish
the cubes and spheres with which he is familiar from touch, proves
to my mind nothing at all against Locke and nothing in favor of
Berkeley and Diderot. Even persons who see recognize figures
that are turned upside down only after much practice. The fact
is that at the first moment of sight all the associations connected
with the optical process, which may subserve its application intel-
lectually, are wanting. A further point is that, when optical
stimuli have been absent for a long period in early youth, the develop-
ment of the central visual spheres may be arrested, or perhaps
degeneration may even take place, as has been shewn by Schnabel's
beautiful observations (" Beitrage zur Lehre von der Schlechtsichtig-
keit durch Nichtgebrauch der Augen," Berichte des naturwissenschaft-
lich-medikalischen Vereins in Innsbruck, Vol. XI., p. 32), and by
Munk's experiments on new-born puppies (Berliner klinische Wochen-
schrift, 1877, No. 35). Even in the case of people who are not
actually blind, the visual sphere may be so little developed that a
special education is required to enable them to turn their sight-sensa-
136 THE ANALYSIS OF SENSATIONS
When I reach out my hand to grasp an object, a sensation
of touch is combined with an innervation. If I look towards
tions to account. The case of the boy described by S. Heller, the
Director of the Vienna Institute for the Blind ( Wiener klinische Wochen-
schrift, 25th April 1901), is probably such a case of partial optical
idiotism. It is only with great caution, therefore, that conclusions
should be drawn from the behaviour, after operations, of those born
blind. Chesselden, for instance, gave an account of an operation
performed on a man blind from birth, who at first believed that every-
thing he saw was in contact with his eyes ; from this the false conclusion
was drawn that the perception of the dimension of depth depends on
extra-optical experiences. An accident put me in the way of under-
standing this phenomenon. once when I was walking on a dark
night in a district with which I was unfamiliar, I was all the time
afraid of running up against a large black object. This turned out to
be a hill several kilometres distant, which brought about this pheno-
menon through my being unable to fix and accommodate my sight,
in much the same way as people who have been newly operated must
be unabk to do. If any one is not convinced by his own stereoscopy
that the dimension of depth also is optically given, he is not likely to
be convinced by the experiences of truncated people without arms and
legs, such as Eva Lark andKobelkoff(G. Hirth, Energische Epigenesis,
1898, p. 165).
All systems of space-sensation, however different they may be, are
connected by a common associative link, the movements which they
serve to guide. If Locke was wrong, how could the blind Saunderson
have written a geometry intelligible to those who are not blind ?
Without doubt there are analogies between the sense of space given
through sight and that given through touch. I have already mentioned
something of this sort in discussing Soret's work (p. n 8, above), and
many of these phenomena were known to the Aristotelian school.
Thus in the Parva Naturalia we find mentioned the experiment by
which a little ball is felt as double when touched by the index-finger
and the middle finger placed across it. With me this experiment
produces an even more striking effect when I cross my fingers and
move them up and down a little stick ; and when I take two parallel
sticks, and arranging my fingers in this way. run them between them,
I feel the two sticks as single. The analogy with seeing the single
as double and seeing the double as single is here complete. But the
differences also are so great that the man of normal sight finds it
difficult to picture to himself a blind man's space-presentation, since
THE ANALYSIS OF SENSATIONS 137
the object, a luminous sensation is substituted for the sen-
sation of touch. Even where objects are not touched, skin-
sensations may always be perceived when the attention is
turned to them, and these, combined with changing inner-
vations, also yield the conception of our body as in motion,
which quite accords with that acquired by optical means.
Thus, in active movements, the skin-sensations are
delocalized, as we may briefly express it. In passive move-
ments of the body, reflex, unconscious compensatory innerva-
tions and movements of compensation make their appearance.
In turning round to the right, for example, my skin-sensations
are compounded with the same innervations as would be
combined with the touching of objects in turning to the right.
I feel myself turning to the right. If I am passively turned
toward the right, the reflex endeavour arises to compensate
the turning. I either actually remain stationary and feel
myself at rest, or I repress the motion toward the left. But
for this I need to exert the same voluntary innervation as
for an active turning to the right, which has also the same
sensation as its result.
8.
At the time when my work on the Sensations of Move-
ment was written, I had not yet attained to a thoroughly
comprehensive view of the simple relation here described.
I encountered, consequently, difficulties in the explanation
of certain phenomena, observed partly by Breuer and
partly by myself, which are now easy of explanation, and
he is always introducing his own visual presentations by way of inter-
pretation. Even so acute a mind as Diderot's can fall on occasion
into the strange error of denying that the blind can imagine space.
Cf. Loeb's work; on tactual space (p. 113, above), and Heller's Studien
zur Blindenpsychologie (Leipzig, 1895). See Chapter IX.
138 THE ANALYSIS OF SENSATIONS
which I will briefly notice. If an observer be shut up in
a closed receptacle, and the receptacle be set in rotation
toward the right, it will appear to the observer as optically
in rotation, although every ground of inference for relative
rotation is wanting. If his eyes perform involuntary com-
pensatory movements to the left, the images on the retina
will be displaced, with the result that he has the sensation
of movement toward the right. If, however, he fixes his
eyes upon the receptacle, he must voluntarily compensate
the involuntary movements, and thus again he is conscious
of movement towards the right. It is plain, therefore, that
Breuer's explanation of the apparent motion of optical
vertigo is correct, and also that this movement cannot be
made to disappear by the voluntary fixation of the eyes.
The remaining cases of optical vertigo noticed in my work
may be disposed of in like manner. 1
In voluntary forward motion or rotation, we have not
only a sensation of every single successive position of the
parts of our body, but also the much more simple sensation
of movement forward or of turning round. As a fact, we
do not compound the notion of forward movement from
the notions of the various individual movements of the
legs, or at least we do not need to do so. There are cases,
indeed, in which the sensation of forward movement is
undoubtedly present while that of the movements of the
legs is equally undoubtedly lacking. This is true, for
instance, of a railway journey, or even of the thought of
a journey, and may occur also in recalling a distant place,
etc. The only possible explanation of this can be that the
1 Grundlinien der Lehre von den Bewegiingsempfindungen, Leipzig,
Engelmann, 1875, p. 83.
THE ANALYSIS OF SENSATIONS 139
will to move forward or to turn about, which furnishes to
the extremities their motor impulses, impulses which may
be further modified by particular innervations, is of a com-
paratively simple nature. The conditions existing here are pro-
bably similar to, although more complicated than, those con-
nected with the movements of the eyes, which Hering has so
felicitously interpreted, and to which we shall presently return.
We shall scarcely go far wrong if we suppose that the
comparatively simple motor-sensations J stimulated from
the labyrinth of the brain stand in the closest connexion
with the will to move. These motor-sensations may also
correspond to the feelings of direction which Riehl has
postulated and investigated, 2 The blind man has them
equally with the man of normal sight, and they probably
form an important part of the foundation on which the
understanding of tactual space reposes.
I summed up a series of observations on optical sensations
and motor-sensations in these words : " It looks as if visual
space would turn into a second space, which is held to be
immovably stationary, although this second space is char-
acterized by complete absence of visibility." The space
which is built up from motor-sensations seems, in fact, to
be the original space. 3
At that time I was preoccupied with physical methods
of thought, and was consequently inclined to believe that
sensations of progressive acceleration behaved in a manner
completely analogous to sensations of angular acceleration.
And in fact every physicist who studies this subject is liable
1 Bewegungsempfindungen ) p. 124.
2 Riehl, Der philosophische Kritizismus, Vol. II., p. 143.
3 Beiuegtingsempfindtingen, p. 26.
140 THE ANALYSIS OF SENSATIONS
to think at once of the three equations for the rotatory
movement of a body and the three equations for its move-
ment of translation. I believed further, that, in accordance
with the principle of specific energy, we ought to assume
special sensations of the position of the head.
Breuer, 1 in a later piece of research, has made it probable
that the sensations of progressive acceleration vanish very
much more quickly than those of angular acceleration, and
that perhaps the organ of the former, at any rate in human
beings, is atrophied. Further, Breuer finds that, except for
the semicircular canals, B, the otolithic apparatus, <9, with
its planes of sliding corresponding to the planes of the
semicircular canals, is the only organ adapted to the signaliz-
ing of progressive accelerations and position simultaneously.
The three components of gravity corresponding to the three
planes of sliding characterize the position of the head. Every
alteration of the position alters these components, and in-
stantaneously sets the apparatus of the semicircular canals
going. But progressive accelerations alter these components
without making any demands on the semicircular canals.
Consequently, according to Breuer, the three combinations,
O alone, O + B, and B alone, would suffice for the decision
of all cases. Thus this theory, if it can be maintained,
would be an important simplification.
If I still had it in my power to carry out experiments, I
would submit the motor-sensations in themselves to a re-
newed and thorough investigation. The difference in the
behaviour of the sensations of angular and progressive
accelerations now seems to me significant. Acceleration of
1 Breuer, " Ueber die Funktion des Otolithen-Apparates," Pfliiger's
Archiv, Vol. XLVL, p. 195.
THE ANALYSIS OF SENSATIONS 141
rotation gives rise to a sensation which, long after the
acceleration has become nil, persists with a decreasing
force which can be quantitatively x measured. Progressive
acceleration is felt in its pure form only in the case of
vertically accelerated falling or rising. When the accelera-
tion vanishes the sensation also disappears quickly. The
simplest means of producing a constant acceleration in a
constant direction with respect to the body is by uniform
rotation. We soon cease to have any sensation of uniform
rotation. But a constant centrifugal acceleration also does
not evoke the illusion of flying away in its direction, but
rather calls up the sensation of changed position, which
sensation again vanishes immediately with the disappearance
of the centrifugal acceleration. Does this mean that pro-
gressive acceleration exhausts itself as a stimulus, or that
when the stimulus becomes constant the sensation changes
in character ? In that case we shall have to suppose that
the sensation is composed of two elements.
We have sensations, not of uniform motion, but only of
acceleration. To the elements of the change in progressive
and angular velocity there correspond elements of the
motor-sensations ; and, of these, those sensations at any
rate which correspond to angular velocities persist with
gradually decreasing force, and moreover are algebraically
summable just like the sensations corresponding to pro-
gressive velocities ; so that a sensation p, corresponding
to the total change in velocity, and consequently to the
velocity attained #, is correlated with a movement, usually
of velocity nil upwards, set up in a short time. 2 Now the
1 Beweg^mgsem.pfind^^ngen, p. 96, Experiment 2.
- Bewegungsempfindungen, pp. 116 sqq.
142 THE ANALYSIS OF SENSATIONS
aggregate of sight and-touch-impressions that we passed in
review increases with p and with the time /. We need not
therefore be surprised that experience teaches us to
interpret p conceptually as a velocity and pt as a path,
although of course p in itself has nothing to do with con-
cepts of spatial measurement. In this way it seems to
me that we get rid of the last remaining paradox in the
theory of the motor sensations. This paradox still troubled
me in 1875, an d I see that it has also troubled others. 1
The following experiments and reflexions, which form a
sequel to an earlier publication of mine, 2 will perhaps assist
us in obtaining a correct view of these phenomena.
If we take our stand upon a bridge, and look fixedly at
the water flowing beneath, we shall generally have the
sensation of being ourselves at rest, whilst the water will
seem in motion. Prolonged gazing, however, as is well
known, almost invariably results in the sensation that
suddenly the bridge, with the observer and his whole
environment, begins to move in the direction opposite to
that of the water, while the water assumes the appearance
of being at rest. 3 The relative motion of the objects is in
1 Bewegungsempfindungcn, p. 122.
8 Bewegungsempfindungen^ p. 85.
3 As we all know, the most varied forms of the same impression are
obtained in the midst of a number of railway trains some of which are
in motion and some at rest. A short time ago, while making a steam-
boat excursion on the Elbe, I was astonished at getting the impression,
just before landing, that the ship was standing still and that the whole
landscape was moving towards it an experience that will be readily
understood from what follows.
THE ANALYSIS OF SENSATIONS 143
both cases the same, and there must therefore be some
adequate physiological reason why at one time one, and at
another another, part of them is felt to move. In order to
investigate the matter at my leisure, I had the simple
apparatus constructed which is represented in Fig. 18. An
oil-cloth of simple pattern is drawn horizontally over two
rollers, two metres long and fixed three metres apart in bear-
ings, and is kept in uniform motion by means of a crank.
Across the oil-cloth and about
thirty centimetres above it,
is stretched a string ff> with
a knot K, which serves as a
fixation-point for the eye of
the observer stationed at A.
Now, if the oil-cloth be set
in motion in the direction of
the arrow, and the observer
follow the pattern with his eyes, he will see it in motion,
himself and his surroundings at rest. on the other
hand, if he gazes at the knot, he and the whole room
will presently appear in motion in the contrary direction
to the arrow, while the oil-cloth will stand still. This
change in the aspect of the motion takes more or
less time according to the mental condition of the
observer, but usually requires only a few seconds. If we
once get the knack of it, the two impressions may be made
to alternate with some rapidity and at will. Every follow-
ing of the oil-cloth brings the observer to rest, every fixation
of K) or non-attention to the oil-cloth, by which its pattern
becomes blurred, sets the observer in motion. Two in-
vestigators, for whom I have the deepest respect, do not
144 THE ANALYSIS OF SENSATIONS
agree with me as to the result of this experiment in the
circumstances indicated. one is William James, 1 the other
Crum Brown. 2 I have performed the experiment over and
over again with the same result. I am at present not in
a position to carry out experiments, and must consequently
renounce any idea of a new test ; but the method of after-
images described by Brown seems to have much to recom-
mend it. I pass over for the moment the different possible
theoretical explanations of the experiment.
10.
This phenomenon, of course, must not be confounded
with the familiar Plateau-Oppel phenomenon, which is a
local retinal effect. In the preceding experiment, the entire
environment, so far as it is distinctly visible, is in motion,
whilst in the latter a moving veil is drawn along in front of
the object, which is at rest. The attendant stereoscopic
phenomena, for example, the appearance of the thread
and knot underneath the transparent oil-cloth, are quite
immaterial in this connexion.
In my book on Bewegungsempfindungen (p. 63) I made it
clear that the Plateau-Oppel phenomenon was the result ot
a peculiar process, which had nothing to do with the other
sensations of movement. I wrote there as follows :
" We must therefore suppose that, during the movement
of an image on the retina, a peculiar process is excited
which is absent during rest, and that in the case of move-
ments in opposite directions, very similar processes are
1 W. James, Principles of Psychology, II., pp. 512, sqq.
2 Crum Brown, " on Normal Nystagmus " (see p. 133 above).
THE ANALYSIS OF SENSATIONS 145
excited in similar organs, processes which are, however,
mutually exclusive, so that with the commencement of the
one, the other must cease, and with the exhaustion of the
one, the other begins."
This statement of mine seems to have been overlooked
by S. Exner and Vierordt, who subsequently expressed
similar views on the same subject.
ii.
Before we proceed to the explanation of the experiment
(Fig. 1 8), it will be well to introduce a few variations. An
observer stationed at B seems, under the same conditions,
to be speeding, with all his surroundings, towards the left.
We now place above the oil-cloth T T, Fig. 1 9, a mirror
S S, inclined at an angle of 45 to the horizon. We
observe the reflexion T T' in S S, after having placed on
our nose a shade n , which intercepts
the direct view of T Thorn the eye, O.
If TT moves in the direction of the
arrow, while we are looking at K f > the
reflexion of K^ we shall presently fancy
ourselves sinking downward with the
whole room, whereas if the motion be
reversed, we shall seem to ascend as Fig- 19.
if in a balloon. 1 Finally, the experi-
ments with the paper drum, which I have elsewhere de-
o
1 Such phenomena often make their appearance quite unsought. As
my little daughter was once standing near a window, on a calm winter's
day, during a heavy snowfall, she suddenly cried out that she and
the whole house were rising upward.
K
146 THE ANALYSIS OF SENSATIONS
scribed, 1 and to which the following explanation also applies,
should be cited here. None of these phenomena are purely
optical, but all are accompanied by unmistakable motor
sensations of the whole body.
12.
What form, now, must our thoughts take on, in order to
acquire the simplest explanatory setting for the preceding
phenomena ? Objects in motion exert, as is well known, a
peculiar motor stimulus upon the eye, and draw our atten-
tion and our gaze after them. If the eye really follows
them, we must assume, from what has gone before, that
the objects appear to move. But if the eye is kept for some
time at rest in spite of the moving objects, the constant
motor stimulus proceeding from the latter must be com-
pensated by an equally constant stream of innervation flow-
ing to the motor apparatus of the eye, exactly as if the
motionless point on which the eyes rest were moving uni-
formly in the opposite direction, and we were following it
with our eyes. But when this process begins, all motion-
less objects on which the eyes are fastened must appear in
motion. It is obviously unnecessary that this stream of
innervation should always be consciously and deliberately
called into action. All that is requisite is that it should
proceed from the same centre and by the same paths as
voluntary fixation.
No special apparatus is necessary for observing the fore-
1 Bewegungsempfindtmgen, p. 85. For more recent experiments see
A. von, Szily, " Bewegungsnachbild und Bewegungskontrast,"
Ztitschrift far Psychologic nnd Physiologic der Sinnesorgane, 1905.
Vol. XXXVIII., p. 81,
THE ANALYSIS OF SENSATIONS 147
going phenomena. They are to be met with on all hands.
I walk forward by a simple act of the will. My legs swing
to and fro without my having to attend to them particularly.
My eyes are fixed steadfastly upon my goal without suffer-
ing themselves to be drawn aside by the motion of the
retinal images consequent upon progression. All this is
brought about by a single act of the will, and this act of the
will itself is the sensation of forward movement. The same
process, or at least a part of it, must also be set up, if the
eyes are to resist for any length of time the stimulus of a
mass of moving objects. Hence the motor sensations ex-
perienced in the above experiments.
The eyes of a child in a railway train will be observed to
follow almost uninterruptedly and with a jerking motion the
objects outside, which appear to it to be running. The
adult has the same sensation if he will passively yield him-
self to the natural impressions. If I am riding forwards,
the whole space to my left, for obvious reasons, rotates, in
the direction of the hands of a watch, about a very distant
vertical axis and the space to my right does the same, but
in the opposite direction. only when I resist following the
objects with my eyes, does the sensation of forward motion
arise.
My views regarding the sensations of movement have
been repeatedly attacked, as is well known, but invariably
the adverse arguments have been aimed solely at the
hypothesis, to which I attached comparatively little import-
ance. That I am ready and willing to modify my views in
accordance with newly discovered facts, the present work
148 THE ANALYSIS OF SENSATIONS
will testify. The decision as to how far I am in the right
I will cheerfully leave to the future. on the other hand, I
should like to mention that observations have been made
that strongly favor the theory propounded by myself, Breuer,
and Brown. To these belong, first, the facts collected by
Dr. Guye of Amsterdam (Du Vertigo de Meniere : Rapport
lu dans la section cFotologie dit congres periodique international
de sciences medicales a Amsterdam^ 1879). Guye observed,
in diseases of the middle ear, that reflex turnings of the
head were induced when air was blown into the cavity of
the tympanum, and found a patient who was able to state
exactly the direction and number of the turnings which he
had felt during the injection of liquids. Prof. Crum Brown
(on a Case of Dyspeptic Vertigo," Proceedings of the
Royal Society of Edinburgh, 1881-1882), has described an
interesting case of pathological vertigo observed in him-
self, which admitted of explanation, as a whole, by the
increased intensity and lengthened duration of the sensa-
tion incident upon every turning of the body. But most
remarkable of all are the observations of William James
(" The Sense of Dizziness in Deaf-Mutes," American Journal
of Otology, Vol. IV., 1882). James discovered in deaf-
mutes a striking and relatively general insensibility to the
dizziness of whirling, often great uncertainty in their walk
when their eyes were closed, and in many cases an astonish-
ing loss of the sense of direction on being plunged under
water, in which case there always resulted alarm and com-
plete uncertainty as to up and down. These facts speak
very strongly in favor of the view, which naturally follows
from my conception, that in deaf-mutes the sense of
equilibrium proper is considerably degenerated, and that
THE ANALYSIS OF SENSATIONS 149
the two other senses that give direction, the sense of sight
and the muscular sense (the latter of which loses all its
points of reference when the weight of the body is neutra-
lized by immersion in water), are rendered proportionately
more necessary.
It is impossible to maintain the view that we arrive at
knowledge of equilibrium and of movement solely by means
of the semi-circular canals. on the contrary, it is extremely
probable that lower animals, in whom this organ is entirely
wanting, also have sensations of movement. I have not yet
been able to undertake experiments in this direction. But
the experiments which Lubbock has described in his work,
Ants, Bees, and Wasps, become much more comprehensible
to me on the assumption of sensations of movement. As
experiments of this sort may be interesting to others, it will
not be amiss perhaps to consider an apparatus which I have
briefly described before (Anzeiger der Wiener Akademie,
3oth December 1876). Other apparatuses of the same kind
have since been constructed by Govi and Ewald. They have
been called "cyclostats."
The apparatus serves for the observation of the conduct
of animals while in rapid rotation. Since, however, the
view of the animal will necessarily be effaced by the rotatory
motion, the passive rotation must be optically nullified and
eliminated, so that the active movements of the animal
alone shall be left and rendered observable. The optical
neutralization of the rotatory motion is attained simply by
causing a totally reflecting prism to revolve, with the aid of
gearing, above the disk of the whirling machine, about
exactly the same axis, in the same direction, and with half
the angular velocity of the disk.
150 THE ANALYSIS OF SENSATIONS
Fig. 20 gives a view of the apparatus. on the disk of the
whirling machine is a glass receiver, g, in which the animals
to be observed are enclosed. By means of gearing the eye-
piece o is made to revolve with half the angular velocity
and in the same direction as g. The following figure gives
the gearing in a separate diagram. The eyepiece oo, and
Fig. 20.
the receiver gg, revolve about the axis A A, while a pair of
cog-wheels, rigidly connected together, revolve about BB.
Let the radius of the cog-wheel act, rigidly connected with
gg, be = r. Then r is the radius of M, and 2^/3 is the
radius of cc t but the radius of dd is = 4^/3, wherewith
the desired relation of velocity between oo and gg is
obtained.
In order to centre the apparatus, a mirror S, provided
with le veiling-screws, is laid upon the bottom of the receiver
THE ANALYSIS OF SENSATIONS 151
and so adjusted that, on rotation, the reflexions in it remain
at rest. It is then perpendicular to the axis of rotation. A
second small mirror, *S', in the silvering of which is a small
hole Zj is so adjusted to the open tube of the eyepiece,
with its reflecting surface downward, that, on rotation, the
images seen through the hole, in the mirrored reflexion of
S' in S, remain motionless. Then S' stands perpendicular
to the axis of the eyepiece. With the aid of a brush we
may now mark upon the mirror S a point P 9 whose position
is not altered on rotation (a result which is easily accom-
plished after a few trials),
and so place the hole in
the mirror S' that it also
remains stationary on
rotation. In this way J
points on both axes of
rotation are found. If
now by means of screws
we so adjust the eye-
piece, that, on looking
through the hole in S',
the point P on S and the reflexion of L in S f (or really the
many reflexions of P and Z) fall on the same spot, then
the two axes are not only parallel but coincident.
The simplest eyepiece that can be employed is a mirror
whose plane coincides with the axis, and I adopted this
device in the initial form of my apparatus. But one-half of
the field of vision is lost by this method. A prism of total
reflexion, therefore, is much more advantageous. Let ABC
(Fig. 22) represent a plane section of such a prismatic eye-
piece cut perpendicularly to the planes of the hypothenuse
Fig. 21.
152 THE ANALYSIS OF SENSATIONS
and the two sides. Let this section include, also, the axis
of rotation onPQ, which is parallel to AB. The ray
which passes along the axis QP must, after refraction and
reflexion in the prism, proceed again along the axis NO
and will meet the eye O in the prolongation of the axis.
This done, the points of the axis can suffer no displacement
from rotation, and the apparatus is centred. The ray in
question must accordingly fall at M, the middle point of
AB, and, hence, since it falls on crown glass at an angle of
incidence of 45, will meet AB
at about 16 40'. Therefore, OP
must be distant about 0*115 AB
from the axis, a relation which
can best be obtained by trial, by
so moving the prism in the eye-
piece that oscillations of the
objects in gg during rotation are
eliminated.
Fig. 22 also shows the field of
vision for the eye at O. The ray
OA, which falls vertically upon
AC, is reflected at AB in the
direction AC and passes out
towards S. The ray OR, on the
other hand, is reflected at B and emerges, after refraction,
in the direction of T.
The apparatus has hitherto proved quite sufficient for
my experiments. If a printed page is placed in gg, and the
apparatus turned so rapidly that the image on the retina is
entirely obliterated, one can easily read the print through
the eyepiece. The inversion of the image by reflexion could
Fig. 22.
THE ANALYSIS OF SENSATIONS 153
be removed by placing a second, stationary reflecting prism
above the revolving prism of the eyepiece. But this com-
plication appeared to me unnecessary.
With the exception of a few physical experiments, I have
hitherto undertaken rotation-experiments only with various
small vertebrates (birds, fishes), and have found the data
given in my work on Motor Sensations fully confirmed.
However, it would probably be of advantage to make
similar experiments with insects and other lower animals,
especially with marine animals.
Such experiments have subsequently been carried out,
with most instructive results, by Schafer (Natunvissen-
schaftliche Wochenschrift, No. 25, 1891), by Loeb (Helio-
tropismus der Tiere, Wiirzburg, 1890, p. 117), and by
others. In my lecture " on Sensations of Direction "
(Schriften des Vereins zur Verbreitung naturwissenschaft-
licher Kenntnisse in Wien, 1897, and Populdrwissenschaft-
liche Vorlesungen, 3rd edition, 1903) will be found the
remainder of what I have to say on the sense of direction.
But I should like to refer particularly to Breuer's researches
on the otolithic apparatus, to Pollak and Kreidl's experi-
ments on deaf-mutes, and above all to Ewald's work of
fundamental importance, Ueber das Endorgan des Nervus
octavus (Wiesbaden, 1892). In the third volume of the
Handbuch der Physiologic des Menschen (1905), by W.
Nagel, there is a full account of the "theory of the
sensations of position, movement, and resistance." Since
for some years past I have not been in a position to
follow the experimental work that has been done in this
department with any closeness, I have asked Professor
Josef Pollak to give an account here of so much of the
154 THE ANALYSIS OF SENSATIONS
most recent work as is likely to interest readers of this
book. Dr. Pollak has very kindly complied with my
request, and the following paragraphs 14-19 are from
his pen.
14.
The results in the course of the last ten years of
morphological research and of research in comparative
and experimental physiology in connexion with the laby-
rinth of the ear (the cochlea, the semicircular canals,
and the otolithic apparatus) have been almost without
exception favorable to the Mach-Breuer hypothesis.
It may now be taken as proved that the organ of hearing
is constituted by the cochlea alone, and that the vestibular
apparatus has no acoustic functions. A complete proof
of this has been furnished by Biehl, 1 who, by intracranial
operations on sheep, succeeded in severing the vestibular
branch of the acoustic nerve without injuring the ramus
cochlearis ; the result was that disturbances of equilibrium
were produced, though the sense of hearing remained
unaffected. Further, that part of the theory of the static
function of the labyrinth is firmly founded and scarcely
open to attack, which regards the semicircular canals as
sense-organs that serve the perception of turnings of the
head (and, mediately, of the body), especially since this
hypothesis has received at the hands of Breuer important
modifications based on his anatomical studies of the
epithelial hairs of the ampullae. 2
1 Karl Biehl, " Ueber intrakranielle Durchtrennung des Nervus
vestibularis und deren Folgen," Sitzungsberichte of the Vienna Academy
of Science, 1900.
2 J. Breuer, "Studien liber den Vestibularapparat," Ibid., Vol. CXIL,
1903.
THE ANALYSIS OF SENSATIONS 155
This hypothesis now runs as follows :
" Persistent uniform rotations are not felt, however
rapid they are ; but the beginning and end of the rotation,
acceleration and retardation, are felt. The ampullary
apparatus is not affected by angular velocities that persist,
but only by positive and negative angular accelerations.
These cause a momentary displacement of the endolymph-
ring and of the cupula terminalis (which as a consistent
mass holds the epithelial hairs together in a constant
figure of fixed shape), and, concomitantly, set up a
tension of the cell-hairs and an excitement of the terminal
apparatus of the nerves on one side of the crista involved.
As long as these excitations last, they give rise to a sensa-
tion of rotation, which persists until the contrary impulse
of negative acceleration, when the rotation stops, or the
gradual effect of the elasticity of the stretched complexes,
restores the normal state of things again."
The system of semicircular canals, moreover, possesses,
like all other sense-organs, the property of giving rise not
only to sensations but also to reflexes (Breuer, Delage,
Nagel). Prominent among reactive organs are the muscles
of the eyes, which communicate rotations to the eyes
when the body rotates.
Previously, however, the opinion had been conjecturally
put forward by Mach that progressively accelerated motion
could exercise no influence on the lymph enclosed in the
semicircular canals; he had also suggested that special
organs exist in the labyrinth for the perception of accelera-
tions and for the sensation of the position of the head.
156 THE ANALYSIS OF SENSATIONS
Breuer then succeeded in making it at least very probable
that this function belongs to the otolithic apparatus. He
supposes that the otoliths exert, by means of their weight,
a definite pressure on the hair-cells underneath them.
Every inclination of the head must change the position
of the sacculus, and consequently that of the sense-
epithelia also. By determining the position of the
directions in which the otoliths slide for different positions
of the head, Breuer shewed that an unambiguous pro-
nouncement as to the position of the head is only made
possible by the co-operation of the two sacks. " For every
position of the head there is only one definite combina-
tion of magnitudes of gravitation of the otoliths in the
four maculae. When, as we suppose, the gravitation of the
otoliths is felt, then every position of the head is charac-
terized by a definite combination of these sensations." In
the case of acceleration in a straight line, every shock that
causes motion will evoke, owing to the inertia of the
otolithic masses, a relative acceleration of these masses
in the opposite direction, this relative acceleration repre-
senting the adequate sensational stimulus.
Heuristically, this part of the hypothesis is now on a very
firm footing. It has become the basis of research on
the lower animals in which otoliths alone occur, and in the
case of higher animals also it has pointed the way to the
isolation and experimental testing of the functions of the
otoliths.
From the mass of facts concerning the lower animals,
which have been discovered of recent years, I will only
select a few pregnant instances. The phenomena that
result on the removal of the otoliths have been studied,
THE ANALYSIS OF SENSATIONS 157
also the behaviour of animals under rotation and the com-
pensatory movements. The experiments of Prentiss, 1 are
particularly interesting. He first repeated Kreidl's famous
experiments in compelling sloughing Crustacea to absorb
" iron " otoliths ; he confirmed the fact that the behaviour
of these towards magnets is in accordance with the theory.
But he was also so fortunate as to obtain observations on
free-swimming larvse of lobsters, which had been deprived
of the power of growing otoliths after they had sloughed
their skin. He was able to convince himself that they
present the same phenomena as full-grown shrimps, from
which the otoliths have been removed : they roll from one
side to another, swim with belly upwards, are more easily
turned over on to their backs than normal larvae, and,
when they are blinded, the loss of equilibrium is still more
striking. The same writer also describes as follows the
behaviour of a crustacean (Virbius zostericula\ in which
the statocyst is normally absent.
" It is not a free-swimming form, but attaches itself to
grasses, in the positions that are independent of gravity.
If it is compelled to swim, it does so in a very uncertain
manner, but generally back upwards. It is easily turned
over on to its back, and, once in this position, is very slow
at setting itself right. Its uncertain manner of swimming
is reminiscent of that of other Crustacea after their stato-
cysts have been destroyed. If the eyes are covered with
lamp-black, all sense of direction in swimming is
lost."
The experiments of Prentiss recall those of K. L.
1 " The Otocyst of Decapod Crustacea, its Structure, Development
and Functions," Bulletin of the Museum of Comparative Zoology ',
Harvard, 1900-1. (Quoted by Kreidl.)
158 THE ANALYSIS OF SENSATIONS
Schafer. 1 Schafer rotated the larvae of frogs, and dis-
covered that the first appearance of rotatory vertigo
coincides in time with the completion of the formation of
the semicircular canals.
Ach's 2 researches on frogs are important. He discovered
that the otoliths are connected with the lid-reflex of the
crossed side ; from the fact that, in the case of a frog de-
prived of its otoliths and subjected to rapid movement,
the lid-reflex vanishes both horizontally and vertically, he
concluded that the function of the otoliths is to subserve
displacements of the body in a straight line in space.
16.
on the other hand, the wheel-like movements of the
eyes that take place when the position of the head under-
goes a series of changes, and the nystagmic movements
caused by rotation and by passing a galvanic current through
the head, have long been known and have been sufficiently
analysed. The typical movements of the head, and the
jerking movements of the eyes which are repeated at
regular intervals when the head is continuously rotated
or when a galvanic current is passed through it, and which
can also be easily felt through the closed eyelids, are sure
objective signs of vertigo. Nystagmus of eyes and head
is completely absent in animals without a labyrinth, as has
been shown by Ewald in the case of doves, and by Breuer
1 K. L. Schafer, " Funktion und Funktionsentwicklung der Bogen-
giinge, Zeitschrift fur Psychologic und Physiologic der Sinnesorgane,
1894.
2 Ach, " Ueber die Otolithenfunktion und Labyrinth tonus," Pfliiger's
Archiv, Vol. LXXXVL, 1900.
THE ANALYSIS OF SENSATIONS 159
in the case of cats, whose nervous octavus had been
severed on both sides. Breuer and Kreidl have proved
that the optical distortion of the vertical, experienced by
anyone who rides in a whirling chair or sits in a railway
train passing quickly enough over a sharp curve, depends
upon a real wheel-like movement of the eyes. Again, we
owe to Breuer the proof that individual ampullae, even
when isolated, can be galvanically stimulated ; when that
is done, they produce a movement of the head in the
plane of the canal involved, whereas, according to Breuer,
the consequence of diffused stimulation is the so-called
galvanotropic reaction, consisting in an inclination of the
head towards the anode.
So much having been premised, the phenomena observed
by James, 1 Kreidl 2 and Pollak 3 as resulting with deaf-
mutes when affected with rotatory or galvanic vertigo, can
easily be explained on the Mach-Breuer theory. Accord-
ing to Mygind, 4 out of 118 deaf-mutes subjected to an
anatomical examination, pathological changes of the
vestibulary apparatus were present in 56 per cent. ; 50 to
58 per cent, of the deaf-mutes experimented on by Kreidl
felt no rotatory vertigo ; 2 1 per cent, of those on whom
Kreidl reproduced the conditions of Mach's experiment
with the whirling chair, did not succumb to the illusion as
to position with respect to the vertical, which is inevitable
1 William James, American Journal of Otology, 1887.
2 A. Kreidl, " Beitrage zur Physiologic des Ohrlabyrinths auf
Grund von Versuchen bei Taubstummen," Pfliiger's Archiv, Vol. LI.
3 J. Pollak, " Ueber den galvanischen Schwindelbei Taubstummen,"
etc., 7^^., Vol. LIV.
4 H. Mygind, " Ueber die pathologisch-anatomischen Veranderungen
der Gehororgane Taubstummer," Ibid., Vol. XXV.
i6o THE ANALYSIS OF SENSATIONS
in normal persons : they also without exception displayed,
when rotated, no reflex movements of the eyes. The
explanation of the lower percentage is that, according to
Mygind's statistics, the semicircular canals are more
frequently found to be diseased than the vestibule.
Pollak found that 30% of the deaf-mutes he investigated
experienced no galvanic vertigo, and that most of the deaf-
mutes who display no eye-movements and no illusion as to
the vertical when placed on the rotating platform or the
whirling chair, are also devoid of the characteristic symptoms
of galvanic vertigo. Further researches by Strehl, Kreidl,
Alexander and Hammerschlag confirmed these facts ; the
three latter discovered, further, that, when the deaf-mutes
were divided into congenital deaf-mutes and those with
acquired deafness, an extremely high percentage of the
former (in Kreidl and Alexander's experiments 84/ , in
Hammerschlag's 95%) displayed normal galvanic reaction,
while only 29% of the subjects with acquired deafness
reacted normally to the galvanic current.
Congenital deaf-mutes, i.e., those with hereditary degenera-
tion, behave in this connexion in the same way as Japanese
dancing mice, the explanation of whose physiological
behaviour lies, as Kreidl and Alexander I have shewn, in
their anatomical structure.
These mice are completely deaf, and progress in a sprawl-
ing, hobbling fashion ; to a superficial observer their power
of equilibrium seems unimpaired ; but if one tries experi-
mentally to get them to move along a narrow path, the
1 Alexander and Kreidl, " Zur Physiologic des Labyrinthes der
Tanzmaus," Pfliiger's Archiv, I., II., III., Vols. LXXXIL,
LXXXVIII.
THE ANALYSIS OF SENSATIONS 161
high degree in which their power of balance is defective
becomes immediately obvious. They are free from rotatory
vertigo, but when a galvanic current is passed through their
heads they behave like normal animals. Anatomical
examination gives the following results. Destruction of the
papilla basilaris cochleae, advanced emaciation of the ramus
inferior of the eighth nerve, advanced atrophy of the spiral
ganglion, destruction of the macula sacculi, medium
emaciation of the branches and roots of the ramus superior
and medius of the eighth nerve, and medium diminution of
both vestibular ganglia.
Among recent experiments in the field of comparative
physiology. those of Dreyfuss 1 seem to me very remarkable.
He observed the behaviour of normal guinea-pigs, and of
guinea-pigs deprived of their labyrinths (operated on one
side only and on both sides), when placed on a rotating
platform, his special object being to study the compensatory
movements of the eyeball and the head. He records a
striking difference in the behaviour under rotation of the
operated animal as contrasted with the behaviour of the
intact animal. The animal that has been deprived of both
labyrinths remains motionless in one place under rotation ;
it displays no displacement of the longitudinal axis of the
vertebral column, and no nystagmus of head or eyes. It
is unconscious of the rotation. To prove this, Dreyfuss
devised the following experiment in feeding the guinea-pigs.
If four of them, one normal, one with the left, one with
1 Dreyfuss, " Experimentale Beitrage zu der Lehre von der nichtakus-
tischen Funktion des Ohrlabyrinthes," Pfluger's Archiv, Vol. LXXXI.
162 THE ANALYSIS OF SENSATIONS
the right, and one with both labyrinths destroyed, are
placed on the rotating platform, and the experimenter waits
until they have all begun to feed, the normal guinea-pig
stops eating during rotation ; the guinea-pig without the
right labyrinth goes on eating while the rotation is to the
right, and stops when it is to the left; the one without
the left labyrinth goes on eating when the rotation is to the
left, and stops when it is to the right ; and the one with
neither labyrinth goes on eating whichever the direction of
rotation. Breuer and Kreidl obtained analogous results
from comparative experiments with normal and acoustically
defective cats.
1 8.
Morphologically, and from the teleological standpoint,
Alexander's work on the organs of equilibrium and hearing
in animals with congenitally defective visual apparatus, the
mole (Talpa europced} and the blind mouse (Spalax typhlus^
is interesting. 1
It is well-known that, in comparison with the lower
animals, the vestibular apparatus in the higher animals and
in man is defectively developed. In the case of all animals
that are able to move in air or water, we find three nerve-
ends carrying statoliths ; in the higher mammals there are
only two. As regards the higher animals, Mach and Breuer
have repeatedly emphasized the fact " that they are far from
meaning to imply that the labyrinth alone furnishes the
sensations necessary for the maintenance of equilibrium ;
1 G. Alexander, " Zur Frage der phylogenetischen Ausbildung der
Sinnesorgane," Zeitschrift fur Psychologic und Physiologic der Sinnes-
organe, Vol. XXXVIII.
THE ANALYSIS OF SENSATIONS 163
rather it co-operates to this end with the sense of pressure
and the muscular sense, as well as with the sense of sight."
It has never been denied, and is indeed quite certain, that
absence or loss of the labyrinth-sensations can to a large
extent be replaced by the other sense-perceptions just
mentioned, so that, as Ewald pre-eminently has shewn, the
major functions of the maintenance of equilibrium, such as
walking and standing, can be adequately performed even
when the labyrinth-function has been lost, or when there is
some congenital defect in it. We see this, not only in the_
case of operated animals, but also in that of those deaf
mutes in whom we have reason to assume some lesion of
the semicircular canals (Breuer). However, James and
Krei'dl have shewn that deaf-mutes who are not subject to
rotatory vertigo are very unskilful in all the more delicate
problems of balance.
The mole, on the other hand, is an animal whose move-
ments take place principally underground, though the
surface on which it moves is solid ; moreover it dispenses
almost completely with any sense of orientation by means
of the organ of sight, and Alexander has shewn that this
is fully compensated by its exquisite power of balance. This
is anatomically expressed by the unusual size of the terminal
nerve cells, by the relatively large number of the sense-cells,
and especially by the presence, in the sinus utricularis
inferior, of a macula neglecta which is wanting in other
mammals, and which, apart from birds and reptiles, has
only been found in one other lower mammal, Echidna
aculeata.
It is Alexander's merit to have proved that, in respect
of the structure of its static terminal nerve-cells, Echidna
164 THE ANALYSIS OF SENSATIONS
represents the hitherto unknown transition from mammals
to birds. Echidna possesses a cortical organ which, in histo-
logical structure, corresponds with that of mammals, whereas
in the number of the other terminal points of nerves it
agrees with the labyrinth of birds ; in addition to the three
macular nerve-terminations (macula utriculi, macula sacculi,
and macula lagenae) it exhibits a macula neglecta Retzii.
19.
The results of these researches, of which only a small
selection has been mentioned, may be summed up as follows.
The compensation in the visual field of every movement of
the head by means of movements of the eyes, which are
carried out also by the blind and by normal persons with
their eyes shut ; the absence of these movements in many
deaf-mutes ; the nystagmus of the eyes that takes place
under continued rotation ; the wheel-like movement of the
eyes when the direction of the acceleration of masses in the
body is altered by a centrifugal force ; rotatory vertigo and
its law; the absence "of this vertigo in many deaf-mutes;
finally, the identical character of galvanic vertigo in man
and in animals, all these facts serve strongly to confirm
the theory of Mach and Breuer, although it cannot be denied
that many questions still remain unsolved. As against other
hypotheses, such as those of Ewald and Cyon, this theory has
at any rate the advantage that, in the case of the ampullary
and otolithic apparatus, it provides a clearer explanation of
the specific disposition to the adequate stimulus than we
have for any other sense organ, and also that, in accord-
dance with it, the two sense-organs in the labyrinth are
THE ANALYSIS OF SENSATIONS 165
readily brought under the principle of specific sense-
energies (Nagel). In any case the sensation of motion is
proved to be a special and peculiar department of sensa-
tion.
20.
Professor Pollak's communication here comes to an end.
Without doing violence to the facts described in my
book on The Sensations of 'Movement ', the preceding observa-
tions suggest the possibility of modifying the theoretical
view there taken of the facts, as we shall point out in what
follows. It remains extremely probable that an organ
exists in the head it may be called the terminal organ
(TO] which reacts upon accelerations, and by means
of which we are made aware of movements. To me person-
ally the existence of sensations of movement, of the same
nature as other sensations, does not seem doubtful, and I
can scarcely understand how anyone, who has really re-
peated on himself the experiments in question, can deny
the existence of these sensations.
But instead of imagining that the terminal organ excites
special motor-sensations, which proceed from this apparatus
as from a sense-organ, we might also assume that this organ
simply disengages innervations after the manner of reflexes.
Innervations may be voluntary and conscious or involuntary
and unconscious. The two different organs from which
these proceed may be designated by the letters WI and
UI. Both sorts of innervation may pass to the oculo- motor
apparatus (OM) and to the locomotor apparatus (LM).
Let us now consider the accompanying diagram. We
induce by the will, that is by a stimulus from WI> an active
166 THE ANALYSIS OF SENSATIONS
movement, which passes in the direction of the unfeathered
arrows, to OM and LM. The appropriate innervation,
whether it precedes or follows the movement, is directly
felt. In this case, therefore, a specific sensation of move-
ment, differing from the innervation, is unnecessary. If the
motion in the direction of the unfeathered arrows is a
passive one (taking us by surprise), then, as experience
shews, reflexes pass from TO to 77, which produce com-
pensatory movements, indicated by the feathered arrows.
If WI takes no part in the process, and the compensation
is effected, both the
motion and the neces-
sity for motor sensa-
tion are absent. But
if the compensatory
movement is inten-
tionally suppressed,
that is, by intervention
Fig. 23. from WI, then the
same innervation is
necessary for achieving this result as for active movement,
and it consequently produces the same motor sensation.
The terminal organ TO is accordingly so adjusted to
WI and UI that upon a given motor stimulus in the first,
contrary innervations are set up in the last two. But
further, we have to notice the following difference in the
relation of TO to fF/and UI. For TO, the motor excita-
tion is naturally the same whether the movement induced
is passive or active. In active movements, too, the inner-
vations proceeding from WI would eventually be neutralized
by TO and UI, did not an inhibitory innervation proceed
THE ANALYSIS OF SENSATIONS 167
simultaneously with the willed innervation from WI to TO
or UI. The influence of TO upon WI must be conceived
as much weaker than its influence upon UI. If we should
picture to ourselves three animals, WI, UI, and TO,
between whom there was a division of labor, such that the
first executed only movements of attack, the second only
those of defence or flight, while the third filled the post of
sentinel, all of whom were united into a single new organism
in which WI held the dominant position, we should have a
conception approximately corresponding to the relation
represented. There is much in favor of such a conception
of the higher animals. 1
I do not offer the preceding view as a complete and
perfectly apposite picture of the facts. on the contrary, I
am fully aware of the defects in my treatment. But the
attempt to reduce to one and the same quality of sensation,
in accordance with the cardinal principle evolved in our
investigation (p. 62), all sensations of space and movement
which arise in the province of sight and touch during
change of place, and which, even when locomotion is only
remembered, or a distant spot only thought of, arise in a
shadowy form, will be found to be not without justification.
The assumption that this quality of sensation is the will,
so far as the will is occupied with position in space and
spatial movement, or that it is innervation, does not fore-
1 If I grasp a little bird in my hand, the bird will behave towards
my hand exactly as a human being would towards a giant cuttle-fish.
In watching a company of little children whose movements are largely
unreflecting and unpractised, the hands and eyes remind one very
strongly of polypoid creatures. Of course, such impressions do not
afford solutions of scientific questions, but it is often very suggestive to
abandon oneself to their influence.
168 THE ANALYSIS OF SENSATIONS
stall future investigation and only represents the facts as
they are known at the present time. 1
21.
From the discussions of the previous chapter relative to
symmetry and similarity, we may immediately draw the
conclusion that to like directions of lines which are seen,
the same kind of innervation-sensations, and to lines
symmetrical with respect to the median plane very similar
sensations of innervation correspond, but that with looking
upwards and looking downwards, or with looking at ob-
jects afar off and at objects near at hand, very different
sensations of innervation are associated, as we should
naturally be led to expect from the symmetrical arrange-
ment of the motor apparatus of the eye. With this single
observation we explain at once a long chain of peculiar
physiologico-optical phenomena, which have as yet received
scarcely any attention. I now come to the point which, at
least from the physical point of view, is the most important.
The space of the geometrician is a mental construction
of three-dimensional multiplicity, that has grown up on the
basis of manual and intellectual operations. Optical space
(Hering's "sight-space") bears a somewhat complicated
geometrical relationship to the former. The matter may
be best expressed in familiar terms by saying that optical
space represents geometrical space (Euclid's space) in a
1 Compare Hering's opinion given in Hermann's Handbiich der
Physiologie^ Vol. III., Part I., p. 547. I do not wish to conceal the
method by which I was led to my theory, although now the view repre-
sented by James, Miinsterberg and Hering, as explained in Chapter
VIII., seems to me preferable.
THE ANALYSIS OF SENSATIONS 169
sort of relievo-perspective a fact which can be teleo-
logically explained. In any event, optical space also is a
three-dimensional multiplicity. The space of the geome-
trician exhibits at every point and in all directions the
same properties a quality which is by no means charac-
teristic of physiological space. But the influence of
physiological space may nevertheless be abundantly
observed in geometry. Such is the case, for example,
when we distinguish between convex and concave curva-
tures. The geometrician should really know only the
amount of deviation from the mean of the ordinates.
22.
As long as we conceive the (12) muscles of the eye to be
separately innervated, we are not in a position to understand
the fundamental fact that optical space is presented as a
three-dimensional multiplicity. I felt this difficulty for
years, and also recognized the direction in which, on the
principle of the parallelism of the physical and the psychical,
the explanation was to be sought ; but owing to my defec-
tive experience in this province, the solution itself remained
hidden from me. All the better, therefore, am I able to
appreciate the service rendered by Hering, who discovered
it. To the three optical space co-ordinates, viz., to the
sensations of height, breadth and depth, corresponds
according to the shewing of this investigator (Hering,
Beitrdge zur Physiologic, Leipzig, Engelmann, 1861-1865;
Die Lehre vom binokularen Sehen, 1868) simply a threefold
innervation, which turns the eyes to the right or to the
left, raises or lowers them, and causes them to converge,
170 THE ANALYSIS OF SENSATIONS
according to the respective needs of the case. This is the
point which I regard as the most important and essential. 1
Whether we regard the innervation itself as the space-
sensation, or whether we conceive the space-sensation as
before or behind the innervation, a question neither
easy nor necessary to decide, nevertheless Hering's
account throws a flood of light on the psychical obscurity
of the visual process. The phenomena cited by myself
with regard to symmetry and similarity, moreover, accord
excellently with this conception. But it is unnecessary,
I think, to dwell any further on this. 2
1 This is the point to which reference was made above (p. 122, note
i, p. 138).
2 This conception also removes a difficulty which I still felt in 1871,
and to which I gave utterance in my lecture on " Symmetry " (Prague,
Calve, 1872), now translated into English in my Popular Scientific
Lectures, Chicago, 1894, in the following words : "The possession of
a sense for symmetry by persons who are one-eyed from birth is certainly
an enigma. Yet the sense for symmetry, although originally acquired
by the eyes, could not have been confined exclusively to the visual
organs. By thousands of years of practice it must also have been
implanted in other parts of the human organism, and cannot, therefore,
be immediately eliminated on the loss of an eye." As a fact, the
symmetrical apparatus of innervation remains, even when one eye
is lost.
VIII. THE WILL.
i.
IN what precedes, the phrase " the will " has often been
used, and has always been intended merely to denote a
generally recognized psychic phenomenon. I do not mean
by the will any special psychical or metaphysical agent, nor
do I assume a specific psychical causality. Rather, I am
convinced, in company with the overwhelming majority of
physiologists and modern psychologists, that the phenomena
of volition must to put it briefly, but in a way that
everyone can understand be explained by means of the
physical forces of the organism alone. I would not lay any
special emphasis on the fact that this is a matter of course,
were it not that the remarks of many critics have shewn the
emphasis to be necessary.
The movements of lower animals, and, equally, the first
movements of all new-born animals, are immediately set
free by some stimulus; they follow the stimulus quite
mechanically;, they are reflex movements. Nor are such
reflex movements absent in the later stages of the lives of
higher animals, and when the occasion arises for us to
observe them for the first time in ourselves, for instance,
the sinew-reflexes, we are as much surprised by them as by
any unexpected event in our environment. The behaviour
of the young sparrow described above (p. 74) depends on
reflex movements. The chick pecks quite mechanically at
171
172 THE ANALYSIS OF SENSATIONS
everything that it sees, just as the child grasps at everything
that strikes its notice, and, on the other hand, withdraws
its limbs from every unpleasant contact without any co-
operation of the intellect. For there are fixed organic
arrangements which determine the preservation of the
organism. If we adopt Hering's views on living sub-
stance, according to which living substance strives towards
the equilibrium of the antagonistic processes taking place
in it, we shall be forced to ascribe to the elements of the
organism themselves this tendency towards self-preservation
or actual stability.
Sensational stimuli can be partly or wholly replaced by
memory-images. All memory-traces that remain behind
in the - nervous system co-operate with the sensations to
set free, to assist, to inhibit and to modify the reflexes. It
is in this way that voluntary movement arises, since we can
conceive voluntary movement, at any rate in principle, as
reflex movement modified by memories, however far we
may fall short of understanding it in detail. The child that
has once burnt itself at a bright flame refrains in future from
grasping at the flame, because the grasp-reflex is inhibited
by the antagonistic avoidance-reflex which the memory of
the pain sets free. The chick begins by pecking at every-
thing; but soon, under the influence partly of inhibitory
and partly of encouraging memories of taste, it exercises a
choice. The gradual transition from reflex movement to
voluntary action can be very prettily followed in the
case of our sparrow (p. 74 above). For the reflecting
subject, the characteristic mark of voluntary action, as
distinct from reflex movement, lies in the subject's re-
cognition that the determining factor in voluntary action
THE ANALYSIS OF SENSATIONS 173
is his own presentations, which anticipate this action
(p. 100 above).
2.
The psychic processes that accompany voluntary action
and voluntary movement have been admirably analysed by
William James x and by Hugo Miinsterberg. 2 It seems a
simple and natural view to suppose that the actual move-
ment is associated with the imagined movement in the same
way as one presentation is associated with another. But
as regards the sensations of the kind and amount of the
movement, and of the amount of effort involved, which
are connected with the execution of the movement, two
opposite views are taken. According to one view, which
is held by Bain, Wundt and Helmholtz, the innervation
which flows to the muscles is itself felt. James and
Miinsterberg take a different view. They hold that all
the kinaesthetic sensations that accompany a movement are
peripherally excited by sensible elements in the skin, the
muscles and the joints.
Against the hypothesis of the central origin of the
kinaesthetic sensations we have to set, first and foremost,
the observations on anaesthetic subjects, 3 who, when their
sensations are cut off, are able to give no account of the
passive movement of their limbs, although they are able to
move their limbs under the guidance of the sense of sight.
We feel the exertion of a faradised muscle just as much
as in the case of a muscle that is voluntarily innervated. 4
1 W. James, Principles of Psychology ', Vol. II., pp. 486 sqq.
2 H. Miinsterberg, Die Willenshandlung, Freiburg im Breisgau, 1888.
3 W. James, op. fit., Vol. II., p. 489.
W. James, op. at., Vol. II., p. 502.
174 THE ANALYSIS OF SENSATIONS
The hypothesis of specific sensations of innervation is not
required for the explanation of the phenomena, and, on the
principle of economy, is consequently to be avoided.
Finally, sensations of innervation are not directly observed.
A special difficulty is constituted by certain optical pheno-
mena, to which we shall return.
The law of association connects not merely processes
that emerge into consciousness (presentations), but also the
most diverse organic processes. The man who blushes
readily when he is embarrassed, whose hands sweat readily,
etc., generally observes these processes taking place in him-
self the moment he is reminded of them. For purposes of
study Newton 1 acquired a dazzling after-image by gazing
at the sun; this image disappeared, but during a period of
several months, although he remained for several days in
the dark, it always returned with full sensational intensity
the moment he reminded himself of it. It was only by
diverting his attention by a long-continued and violent
psychic effort that he was able to get rid of this trouble-
some phenomenon. Boyle narrates a similar observation
in his book on colors. When brought into connexion
with these facts, the association of motor processes with
presentations ceases to appear strange.
An apoplectic stroke which I experienced in 1898, with-
out its in the least affecting my consciousness, has made
me personally familiar with part of the facts now under
1 King's Life of Locke, 1830, Vol. I., p. 404 ; Brewster, Memoirs of
Newton, 1855, Vol. I., p. 236.
THE ANALYSIS OF SENSATIONS 175
consideration. I was in a railway train, when I suddenly
observed, with no consciousness of anything else being
wrong, that my right arm and leg were completely paralysed;
the paralysis was intermittent, so that from time to time I
was able to move again in an apparently quite normal way.
After some hours it became continuous and permanent,
and there also set in an affection of the right facial muscle,
which prevented me from speaking except in a low tone
and with some difficulty, I can only describe my condition
during the period of complete paralysis by saying that when
I formed the intention of moving my limbs I felt no effort,
but that it was absolutely impossible for me to bring my
will to the point of executing the movement. on the other
hand, during the phases of imperfect paralysis, and during
the period of convalescence, my arm and leg seemed to me
enormous burdens which I could only lift with the greatest
effort. It seems to me plausible to suppose that this was
caused by the energetic innervation of other muscle-groups
in addition to the muscles of the paralysed extremities. 1
The paralysed limbs retained their sensibility completely,
except for one place on the thigh, and thus I was enabled
to be aware of their position and of their passive movements.
I found that the reflex excitability of the paralysed limbs
was enormously heightened; this expressed itself particu-
larly in violent jerks on the slightest alarm. Optical and
tactual motor-images persisted in my memory. Very often
during the day I formed the intention to do something with
my right hand, and had to think of the impossibility of
doing it. To the same source are to be referred the vivid
dreams which I had of playing the piano and writing,
1 W. James, op. cit. y Vol. II., p. 503.
176 THE ANALYSIS OF SENSATIONS
accompanied by astonishment at the ease with which I
wrote and played, and followed by bitter disappointment
on awaking. Motor hallucinations also occurred. I often
thought that I felt my paralysed hand opening and shutting,
and at the same time the total movement seemed to be
hampered as if by a loose, but stiff glove. But I had only
to look to convince myself that there was not the slightest
movement. Over the flexors of this hand I have ac-
quired a very slight control, but over the extensors none
at all.
Since the sensibility of the hand is preserved, while the
power of voluntary movement is lacking, I do not know
how to explain the illusion of movement properly, even on
the new theory. The muscles that are withdrawn from the
influence of the will react now to the most diverse stimuli,
so that the hand is sometimes extended and sometimes
clenched. Strong tastes of different qualities seem to act
as stimuli to different extents on different muscles of my
paralysed hand. Water impregnated with sulphate of
magnesia, for example, excites involuntary movements of
tension in the thumb and the two fingers next to it.
The theory of James and Miinsterberg fits these facts,
as I think, without any straining, and we ought therefore to
consider it as correct in essentials. The innervation is not
felt, but the consequences of the innervation set up new
peripheral sensible stimuli, which are connected with the
execution of the movement. There are, however, some
difficulties which prevent me from believing that this view
THE ANALYSIS OF SENSATIONS 177
which was originally my own, 1 completely explains the
facts.
one would think that the central process which condi-
tions the mere presentation of a movement must differ in
some respect from the process which also releases an actual
movement. To be sure, the strength of the process, the
absence of antagonistic processes, and the extent to which
the innervation-centres are charged, may be partial deter-
minants; but still it is scarcely possible to deny that
further explanation is required. In particular, the difference
in behaviour of the muscles of the eye and the other
muscles that can be excited at will needs closer investiga-
tion. Most muscles have variable amounts of work to
perform, and it is of practical importance for us to know
these amounts approximately. The work done by the eye-
muscles, on the other hand, is small, and is always exactly
connected with the alteration in position of the eyes ; this
latter alone is of optical importance, while the work" as such
is matter of indifference. This may be the reason why the
kinaesthetic sensations play such a much greater part in the
case of the muscles of the extremities.
5-
Hering 2 has shewn how small is the importance of the
sensations proceeding from the muscles of the -eye.
1 Before the phenomena connected with paralysis of the eye-muscles
were known to me, z'.<?., before 1863.
2 Hering in Hermann's Handbuch der Physiologie^ Vol. III., I, 547.
Cf. also Hillebrand, " Verhaltnis der Akkommodation und Konvergenz
zur Tiefenlokalisation," Zeitschrift fur Psychologic und Physiologic der
Sinnesorgane t Vol. VII., pp.97, sqq.
M
178 THE ANALYSIS OF SENSATIONS
Usually we scarcely attend at all to the movements
of our eyes, and the position of objects in space remains
uninfluenced by these movements. If one imagines two
spherical surfaces, covered with movable retinae, and
remaining fixed in space while the retinse revolve, a super-
ficial consideration might even induce us to believe that
the space-values of the objects seen would only be deter-
mined by the two positions of reflexion on the fixed
spheres. But the facts mentioned on p. 127 above, compel
us to separate these space-values into two components, one
of which depends on the co-ordinates of the point of
reflexion on the retina, and the other on the co-ordinates
of the point of vision, which components undergo mutually
compensating alterations corresponding to voluntary altera-
tions of the point of vision. 1 Now, if we refuse to admit
a sensation of innervation, and deny the importance of
the peripherally excited kinaesthetic sensations of the eye-
muscles, the only remaining alternative is that adopted by
Hering, namely to regard the position of attention as
determined by a definite psycho-physical process, which at
the same time is the physical factor that releases the corre-
sponding innervation of the eye-muscles. 2 But this process
is still a central process, and "attention " remains scarcely
different from " the will to see." In this way I might still
hold in essentials to my ｅxpression on p. 130 above; for
which of the series of processes excited from and pro-
1 Cf. p. 114 above ; Hering, op. ?., pp. 533, 534. I am now unable
to decide whether the view that the alteration of the space-values is
completed immediately with the change in attention can be brought
into harmony with the fact mentioned on p. 130 above.
- Hering, op. cit. t pp. 547, 548.
THE ANALYSIS OF SENSATIONS 179
ceeding from the centre is the one that enters into
sensation, is a many-sided problem which can for the
present remain unsolved.
6.
In conformity with what precedes, we might replace, in
the explanation attempted on p. 166 above, the two
antagonistic innervations by two antagonistic processes of
attention, one excited by the sensible stimulus, and the
other a central process. I cannot give my assent to the
explanation proposed by James 1 of the phenomena con-
nected with paralysis of the muscles of the eye, since this
explanation seems, formally at any rate, to drift towards
the doubtful waters of " unconscious inferences." In the
case under discussion we are concerned with sensations
and not with the results of reflexions.
The function of the muscles of the eyes is merely to
ensure our orientation in space ; that of the muscles of the
limbs is principally the performance of mechanical work.
We thus have here two extreme cases, between which there
will lie many middle terms. When we see the newly-
hatched chick pecking and hitting its mark accurately, it is
easy to believe that the muscles of its neck and head to
some extent perform a similar office to that of its eye-
muscles, and act as an apparatus of spatial orientation.
Probably the jerking movements of the head which take
place in birds when they walk forward, are executed, like
nystagmic movements of the head under rotation, in the
1 W. James, op. cit. y Vol. II., p. 506.
i8o THE ANALYSIS OF SENSATIONS
interests of orientation. The muscles of the extremities
also cannot be entirely without analogy to the eye-muscles.
Otherwise how could we understand the blind man's tactual
presentation of space ? For it is not easy to combine a
nativistic theory of visual space with an empirical theory
of tactual space. 1
1 Cf. p. 135 above, note 2, and p 138.
IX. BIOLOGICO-TELEOLOGICAL
CONSIDERATIONS AS TO SPACE. 1
i.
WE have already repeatedly had occasion to notice
how very different the system of our space-sensa-
tions our physiological space, if we may use the ｅxpression
is from geometrical (by which is here meant Euclidean)
space. This is true, not only as regards visual space, but
also as regards the blind man's tactual space in comparison
with geometrical space. Geometrical space is of the same
nature everywhere and in all directions, it is unlimited and
(in Riemann's sense) infinite. Visual space is bounded and
finite, and, what is more, its extension is different in
different directions, as a glance at the flattened " vault of
heaven " teaches us. Bodies shrink when they are removed
to a distance ; when they are brought near they are enlarged :
in these features visual space resembles many constructions
1 This subject cannot be treated in detail here. I may refer to my
articles in The Monist> of which the first appeared in April 1901, the
second in July 1902, and the third in October 1903. The physiological
considerations outlined here are partly related to Wlassak's views as
stated in his paper, " Ueber die statischen Funktionen des Ohrlaby-
rinthes " Vierteljahrsschrift fur wissenschaftliche Philosophic^ Vol.
XVII., I, p. 28), except that I assume, not one, but two, reactions to
the stimuli in question. Cf. also the passages cited above from Hering,
and W. James, Psychology, Vol. II., pp. 134, sqq. Cf. also my
Erkenntnis imd Itrtum, 1905, pp. 331-414, 426-440,
181
182 THE ANALYSIS OF SENSATIONS
of the metageometricians rather than Euclidean space.
The difference between "above" and "below," between
" before " and behind," and also, strictly speaking, between
"right and left," is common to tactual space and visual
space. In geometrical space there are no such differences.
For man, and for animals of similar structure to man,
physiological space is related to geometrical very much as
a "triclinal" is to a "tesseral" medium. This is true for
men and animals, so long as they are not endowed with
freedom of movement and of orientation. When mobility
is added, physiological space approximates to Euclidean,
though without completely attaining to the simplicity of the
properties of Euclidean space. Three-dimensional multi-
plicity and continuity are common to geometrical and to
physiological space. To the continuous movement of a
point A in geometrical space, corresponds a continuous
movement of a point A' in physiological space. We have
only to remember the difficulties which the doctrine of the
antipodes had to overcome, to see how geometrical space-
presentations can be disturbed by physiological. Even our
most abstract geometry does not employ purely metrical
notions, but uses also such physiological conceptions as
direction, sense, right, left, etc.
In order to keep the physiological and geometrical
factors completely apart, we have to reflect that our space-
sensations are determined by the dependence of the
elements which we have called ABC... upon the
elements of our body K L M . . . but that geometrical
conceptions are formed by means of the spatial comparison
of bodies by the relations of the A B C's ... to one
another.
THE ANALYSIS OF SENSATIONS 183
If we consider the spatial sensations not as isolated
phenomena, but in their biological connexion, in their
biological function, they become easier to understand, at
any rate teleologically. As soon as an organ or a system of
organs is stimulated, movements take place as reflex
reactions ; these movements are generally purposive, and
may be defensive or offensive, according to the nature
of the stimulus. For example, different places on the skin
of a frog may be successively stimulated by dropping acid
on them. To each excitation the frog will reply by a
specific defensive movement according to the spot stimu-
lated. The stimulation of places on the retinae sets free
the equally specific reflex of snapping. That is to say,
alterations that make their entrance into the organism by
different paths are reproduced externally also by different
paths on the animal's environment. Now, let us suppose
that, in complicated conditions of life, such reactions can
also arise spontaneously by memory, that is to say, on a
slight impulse, and that they can be modified by memories ;
then traces, corresponding to the nature of the stimulus
and to the stimulated organs, must remain behind in the
memory. As our observation of ourselves teaches us, we not
only recognize identity of quality in the stimulus of burning,
whatever be the spot burnt, but at the same time we
distinguish between the spots stimulated. We must there-
fore suppose that there is attached to the qualitatively
identical sensation an element of difference, which depends
on the specific nature of the elementary organ stimulated,
on the spot stimulated, or, to use Hering's ｅxpression, on
184 THE ANALYSIS OF SENSATIONS
the "place of attention." It is precisely in the perception
of space that the intimate mutual biological adaptation of a
multiplicity of connected elementary organs is displayed
with peculiar clearness.
3-
Let us assume only one kind of element of consciousness,
namely sensations. In so far as we have spatial perceptions,
these depend, according to our theory, on sensations. What
is the nature of these sensations, and what organs are active
in connexion with them, we must leave an open question.
We have to imagine a system of elementary organs of
common embryological origin as being naturally so arranged
that neighbouring elements display the greatest ontological
affinity, and that this affinity decreases as the segregation
of the elements from one another increases. The organic
sensation, which alone depends upon the individuality of
the organ, and which varies with the variation in the degree
of affinity, will correspond to the sensation of space, and
from this we distinguish the sensations which depend on
the quality of the stimulus as specific sensations. Organic
sensations and specific sensations can only appear con-
comitantly. 1 But, over against the varying specific sensa-
tions, the unchanging organic sensations presently constitute
a fixed register, in which the former are arranged. We are
here only making as to the elementary organs similar pre-
suppositions such as we should find natural in the case of
separated individuals of the same descent but of different
degrees of affinity.
1 Similarly the internal organs are only sensed and localized when
some disturbance of their equilibrium takes place.
THE ANALYSIS OF SENSATIONS 185
The perception of space has arisen from biological
necessities, and can best be understood by reference to
these necessities. An endless system of space-sensations
would not only be purposeless for the organism, but would
also be physically and physiologically impossible. Space-
sensations which should be orientated with reference to
the body would also be valueless. It is also advantageous
that, in visual space, the sensation-indices for nearer objects,
which are biologically the most important, should be more
sharply graded, while as regards more remote, and con-
sequently less important, objects, the limited supply of
indices is used economically. This relation, again, is the
only one physically possible.
The following considerations enable us to understand the
motor organization of the visual apparatus. The greater
clearness and the finer distinctions that exist at a given
spot on the retina of the eye of a vertebrate are an economic
arrangement. By this means a movement of the eyes that
follows a change of attention is recognized as advantageous,
just as the influence of a voluntary movement of the eyes
on the space-sensation caused by objects at rest is re-
cognized as disadvantageous, if it is misleading. Neverthe-
less the displacement of images on the retina, which itself
remains at rest, is biologically necessary, in order to enable
us to perceive moving objects with our eyes at rest : the
only case in which it is unnecessary for the organism, is
the very rare one when it is required to perceive an object
at rest when the eye is moved by some cause that does not
emerge into consciousness, such as an external mechanical
186 THE ANALYSIS OF SENSATIONS
force or a twitching of the muscles. The only solution that
provides for all the foregoing requirements is that, when the
eye is moved voluntarily, the displacement of images on the
retina corresponding to this movement should be com-
pensated by the voluntary movement in respect of space-
value. But from this it follows, that when the eye is kept
still, the mere intention to move the eye must cause objects
at rest to undergo some displacement in visual space. By
means of a suitable experiment (p. 128 above) the existence
of the second also of the two mutually compensatory com-
ponents is directly proved. These organic arrangements
are ultimately the reason why under peculiar circumstance,
when our eyes are at rest, objects at rest appear to move
and the space-values to fluctuate, why we see bodies in
motion, which nevertheless do not change their position
relative to our body, and neither move farther away nor
come nearer. What seems paradoxical under these peculiar
circumstances, is, under ordinary circumstances (those of spon-
taneous locomotion) of the highest biological importance.
The relations of tactual space are, apart from certain
peculiarities, similar to those of visual space. The sense
of touch is not a long-range sense ; there is no perspec-
tival shrinkage and enlargement of tactual objects. But
otherwise the phenomena which we find here are akin
to those of vision. The finger-tips correspond to the
macula lutea. We can tell the difference perfectly well
between passing our finger-tips over a motionless object
and the movement of an object over our motionless finger-
tips. Analogous paradoxical phenomena connected with
rotatory vertigo appear here also. They were known to
Purkinje.
THE ANALYSIS OF SENSATIONS 187
Biological considerations of a general nature force us to
conceive optical and tactual space as homogeneous. A
newly-hatched chick notices a small object and at once
both looks and pecks at it. The stimulus excites a certain
tract of the sense-organ and of the central organ, by means
of which both the looking movement of the eye-muscles and
the pecking movement of the muscles of the head and neck
are released perfectly automatically. The excitement of one
and the same nerve-tract, which, on the one hand, is deter-
mined by the geometrical position of the physical stimulus,
must, on the other hand, be regarded as the foundation of
the sensation of space. A child that notices a glittering
object, then looks at it and grasps at it, behaves in the
same way as the chick. In addition to optical stimuli there
are others acoustic stimuli, stimuli of heat and smell
which can also release movements of grasping or of defence ;
and these of course are operative with blind people also.
Again, the same places of stimulus and the same sensations
of space will correspond to the same movements. In
general, the stimuli that excite a blind person are only con-
fined to a narrower sphere and are less clearly and definitely
localized. The system of his space-sensations will con-
sequently be rather poorer and more blurred than that of
a normal person, and, in the absence of a special education,
will even remain so. Consider, for example, a blind man
who tries to keep off a wasp that is buzzing round him.
Accordingly as an object stimulates me to turn my gaze
upon it, or stimulates me to seize it, the tracts of the central
organ that come into play must be partially different,
i88 THE ANALYSIS OF SENSATIONS
although adjacent. If the two stimuli take place at once,
the tract involved is of course larger. on biological
grounds we should expect that the space-sensations con-
nected with different senses, which, though not identical,
are closely akin to one another, would be linked together
by means of the movements which they induce, move-
ments which are directed to the preservation of the
organism, would merge into one another by way of
association, and would mutually support one another ; and
this is in fact the case.
But this conclusion does not exhaust the phenomena
with which we are concerned. A chick may look at an
object or may peck at it ; it may also be determined by
the stimulus to turn towards it and to run up to it.
Exactly similar is the behaviour of a child that crawls
towards some goal, and then one day stands up and runs a few
steps towards the goal. All these cases pass gradually over
into one another, and we have to think of them all as homo-
geneous. Probably there are always certain parts of the brain
which! when stimulated in a relatively simple manner, deter-
mine space-sensations on the one hand, and on the other hand
release automatic movements which are sometimes extremely
complicated. Optical, thermal, acoustic, chemical and
galvanic stimuli can excite a great deal of locomotion and
change of orientation, and these effects can be produced even
in animals that are blind, either originally or by degeneration.
6.
When we observe a millipede (fulus) crawling regularly
on its way, we cannot resist the thought that a uniform
THE ANALYSIS OF SENSATIONS 189
current of stimulus proceeds from some one of the insect's
organs, and that the motor organs of the successive
segments of the body reply to this current with rhythmic
automatic movements. The longitudinal wave, which
seems to pass along the insect's rows of feet with machine-
like regularity, arises from the difference in phase of the
segments behind as compared with those in front. We
should expect to find analogous processes in the more
highly organized animals, and in fact such processes occur.
I need only refer to the phenomena connected with stimula-
tions of the labyrinth, for instance to the well-known
nystagmic movements of the eyes, which are released under
active and passive rotation. Now, if there are organs, as in
the case of the millipede, by the simple stimulation of
which, the complicated movements of a definite kind of
locomotion are induced, then we may regard this simple stimu-
lation, in the case where it is present to consciousness, as the
will to the locomotion in question, or as the attention to
the locomotion, which automatically draws the locomotion
after it. At the same time, we recognize that it is a necessity
for the organism to feel the effect of the locomotion in a
correspondingly simple manner. And, in fact, objects of
sight and touch do appear with varying and fluctuating
space-values, instead of their values being stable. Even if
we exclude all sensations of sight and touch as completely
as possible, there still remain sensations of acceleration,
which evoke, by way of association, the images of the
various space-values with which they have often been con-
nected. Between the first and last members of the process
lie the sensations of movement in the extremities, whicrij
however, are usually only fully present to consciousness
igo THE ANALYSIS OF SENSATIONS
when some obstacle arises and makes a modification of the
movement necessary.
The man who is motionless as a whole is only aware of
space-sensations which are limited, locally individualized,
and orientated with reference to his own body; but the
sensations which arise on occasion of locomotion and
change of orientation possess the character of regularity
and inexhaustibility. All these experiences are required
as a basis for the construction of a conception of space
approximately similar to Euclidean space. Apart from the
fact that the first set of experiences only gives us agree-
ments and differences, but no magnitudes and no metrical
determinations, the latter set does not attain absolute
uniformity on account of the obstacles in the way of
permanent and free disorientation in respect of the
vertical.
For the animal organism, the relations between the parts
of its own body are, first of all, of the highest importance.
An alien object only acquires value by standing in relation
to parts of the animal's own body. In the lowest organisms
the sensations, including the space-sensations, are sufficient
to secure adaptation to primitive conditions of life, But
as these conditions become more complicated they force
on the development of the intellect. Then the mutual
relations of those functional complexes of elements
(sensations) which we call bodies, acquire an indirect
interest. Geometry arises from the spatial comparison
of bodies with one another.
Our understanding of the development of geometry may
THE ANALYSIS OF SENSATIONS 191
be assisted by the observation that our immediate interest
is connected, not with spatial properties alone, but with
the whole permanent complex of material properties which
is important for the satisfaction of our needs. But the
forms, positions, distances, and extensions of bodies are
decisive for the mode and the quantity of the satisfaction
of needs. Mere perception by itself (estimation, ocular
measurement, and memory) proves to be too much under
the influence of physiological circumstances that are not
easily controlled, for us to build securely upon it, when
the question is one of judging accurately the spatial
relations of bodies to one another. We are therefore
compelled to look to the bodies themselves for trust-
worthy indications.
Everyday experience brings home to us the permanence
of bodies. Under ordinary circumstances this permanence
extends also to particular qualities, such as color, shape,
and size. We become acquainted with rigid bodies, which,
in spite of their mobility in space, always produce the
same space-sensations as soon as they are brought into a
definite relation with our body and are seen and handled.
Such bodies display spatial substantiality ; l they remain
spatially constant and identical. one rigid body A may
be immediately or mediately superimposed spatially on
another rigid body B, or on parts of it, and this relation
remains always and everywhere the same. We then say
B is measured by A. When bodies are compared with
1 It is certain that this view has been privately held by innumerable
geometricians. It comes out clearly in the whole arrangement of
Euclid's geometry, and is still clearer in Leibniz, particularly in his
"geometrical characteristic." But Helmholtz was the first to discuss
it openly.
192 THE ANALYSIS OF SENSATIONS
one another in this way, the question is no longer one
as to the kind of space-sensation involved; rather, we
have a judgment as to their identity under similar circum-
stances, and this judgment is formed with great accuracy
and certainty. Variations in the results of measurement
are, in fact, negligible in comparison with the element
of error involved in immediate spatial judgments as to
juxtaposed or successive bodies, and it is in this fact that
the advantage and the rational justification of the process
of measurement consist. Instead of the individual hands and
feet, which everyone carries about with him without noticing
any appreciable spatial change in them, a universally acces-
sible standard of measure is soon chosen, which, by fulfilling
in a high degree the condition of immutability, ushers in an
era of greater precision.
8.
The object of all geometrical problems is to establish
a numerical correspondence between spaces that it is
required to ascertain and known homogeneous bodies.
Empty vessels for the measurement of fluids, or of com-
pact aggregates of almost exactly similar bodies, are
probably the oldest measures. The volume of a body,
the aggregate of the positions occupied by its matter,
which we instinctively represent to ourselves when we
look at or grasp some body with which we are familiar,
comes to be considered as a quantum of material properties
that satisfy our needs, and constitutes, as such, an object
of dispute. Indeed, originally the measurement of a surface
is undertaken solely with the object of ascertaining the
amount of the homogeneous closely juxtaposed bodies
THE ANALYSIS OF SENSATIONS 193
covering the surface. Measurement of length, that is
to say, enumeration by means of similar pieces of string
or chain, determines the minimum volume that can be
interpolated in one and only way between two points,
or two very small bodies. If in this process we abstract
from one or two dimensions of the bodies used as
measures, or, again, if we suppose these bodies to be
everywhere constant, but as small as we like to choose
them, we arrive at the idealized representations of geometry.
Our intuition of space is enriched by experimenting with
material objects, owing to the fact that metrical experiences,
which spatial intuition would not be able to acquire by
itself, are connected with these objects. Thus we become
acquainted with the metrical properties of forms with which
we have long been familiar, such as the straight line, the
plane, and the circle. Again it is experience, as history
testifies, which has first led to the knowledge of certain
geometrical propositions, by shewing that, if an object has
certain dimensions, certain other dimensions of it were
thereby determined. Scientific geometry set itself the
economical task of ascertaining the dependence of dimen-
sions on one another, of avoiding superfluous measurements,
and of discovering the simplest geometrical facts from which
the remaining facts would follow as logical consequences.
For this purpose, since we have no mental control over nature,
but only over our own simple logical constructions, our
ultimate geometrical experiences had to be conceptually
idealized. Henceforth there was no obstacle in the way of
i 9 4 THE ANALYSIS OF SENSATIONS
the discovery of geometrical propositions by a kind of
"thought-experiment," by advancing along the road of
mental visualization, and thinking of these representations as
connected with the idealized geometrical experiences. The
procedure throughout is analogous to that of all the natural
sciences. But the ultimate experiences of geometry are
reduced to so small a minimum that is only too easy to
overlook them altogether. We imagine bodies as moving
over the shadows or ghosts of bodies, and we cling mentally
to the notion that their measurements, if they were taken,
would not be altered in the process. Physical bodies
harmonize with the results in so far as they are sufficient for
the presuppositions.
Intuition, physical experiences, and conceptual idealiza-
tion, are, therefore, the three co-operating factors in
scientific geometry. The wide divergence in the views of
different investigators as to the nature of geometry is due
to over or under estimation of one or the other factor.
The only possible foundation for a correct view is the
precise separation of the part played by each of these factors
in the building up of geometry. For instance, our
anatomically symmetrical motor organization, which has
been acquired for purposes of rapid locomotion, causes our
intuition to make the two halves of a spatially symmetrical
construction appear to us as equivalent ; but this is by no
means true from a physico-geometrical point of view, since
they cannot be brought into congruence. Physically they
are no more equivalent than a movement is to an opposite
movement, or a rotation to a rotation in the opposite
direction. Kant's paradoxes on this subject depend on an
inadequate separation of the various factors involved.
X. THE RELATIONS OF THE
SIGHT-SENSATIONS TO onE
ANOTHER AND TO OTHER
PSYCHICAL ELEMENTS.
i.
IN normal psychical life, sight-sensations do not make
their appearance alone, but are accompanied by other
sensations. We do not see optical images in an optical
space, but we perceive the bodies round about us with their
many and varied sensible qualities. Deliberate analysis is
needed to single out the sight-sensations from these com-
plexes. But even the total perceptions themselves are
almost invariably accompanied by thoughts, wishes, and
impulses. By sensations are excited, in animals, the move-
ments of adaptation demanded by their conditions of life.
If these conditions are simple, altering but little and slowly,
immediate sensory excitation is sufficient. Higher intel-
lectual development is unnecessary. But the case is
different where the conditions of life are intricate and
variable. Here so simple a mechanism of adaptation cannot
develop, still less would it lead to the accomplishment of
the required ends.
Lower species devour everything that comes in their
way and that excites the proper stimulus. A more highly
developed animal must seek its food at risks to itself;
when found, must seize it at the right spot, or capture it by
195
196 THE ANALYSIS OF SENSATIONS
cunning, and cautiously test its character. Long trains of
varied memories must pass before its mind before one is
sufficiently strong to outweigh the antagonistic considera-
tions and to excite the appropriate movement. Here,
therefore, a sum of associated remembrances (or experi-
ences) coincidently determining the adaptive movements,
must accompany and confront the sensations. In this
consists the intellect.
In the young of higher animals under complex conditions
of life, the complexes of sensations necessary to excite
adaptive movements are frequently of a very complicated
nature. The sucking of young mammals, and the be-
haviour of the young sparrow described on pp. 74, 75 are
good examples of this. With the development of intelli-
gence, the parts of these complexes necessary to produce
the excitation constantly diminish, and the sensations are
more and more supplemented and replaced by the intellect,
as may be daily observed in children and adolescent animals.
In a note to the edition of 1886 I uttered a warning
against the tendency, which was still widespread at that
time, to over-estimate the intelligence of the lower animals.
My view was based solely on occasional observations on the
machine-like movement of beetles, the flight of moths
towards the light, etc. Subsequently the important works
of J. Loeb appeared, and provided a solid experimental
basis for this view.
At the present moment (1906) the psychology of the
lower animals has again become the field of much contro-
versy. While A. Bethe l advocates an extreme reflex-theory,
1 A. Bethe. " Diirfen wir den Ameisen und Bienen psychische
Qualitaten zuschreiben ? " Pfliiger's Archiv, Vol. LXX., p. 17; " Noch
THE ANALYSIS OF SENSATIONS 197
based on ingenious and interesting experiments on ants and
bees, according to which these insects are to be regarded
as Cartesian machines, other careful critical observers,
such as E. Wasmann, 1 H. von Buttel-Reepen, 2 and A.
Forel 3 ascribe to the same insects a high degree of psychic
development. The psychology of the higher animals also
has lately become the object of general interest. The
writings of Theodor Zell, which are intended principally
for the general public, are full of excellent observation and
felicitous insight, and seem to hit with great caution the
proper mean between over-estimating and under estima-
ting the animals of which they treat.
Anyone who has studied physiology, or even anyone who
can appreciate the work of F. Goltz, knows the very
important part played by reflexes in preserving the life of
all animal organisms, even of the human organism, which
is the most highly developed of all. To anyone, again,
who has observed the striking way in which the influence
exercised upon the biological reactions by a memory that
einmal fiber die psychischen Qualitaten der Ameisen," Ibid,, Vol.
LXXIX., p. 39 ; Beer, Be the and Uexkiill, " Vorschlage zu einer objek-
tivierenden Nomenklatur in der Physiologic des Nervensystems,"
Centralblatt far Physiologic, 1899, Vol. XIII., No. 6; H. E. Hering,
" Inwiefern ist es moglich die Physiologic von der Psychologic sprach-
lich zu trennen?" Detitsche Arbeit, ist year, No. 12.
1 E. Wasmann, Die psychischen Fiihigkeiten der Ameisen, Stuttgart
1899 (Zoologica, No. 26) ; Vergleichende Studien Uber das Seelenleben
der Ameisen ttnd der hb'heren Tiere, 2nd edition, Freiburg im
Breisgau, 1900.
2 H. v. Buttel-Reepen, Sind die Bienen Reflexmaschinen?, Leipzig-,
1900.
3 A. Forel, " Psychische Fahigkeiten der Ameisen," Transactions of
the Fifth International Zoological Congress, Jena, 1902 ; " Experiences
et remarques critiques sur les sensations des insectes," Rivista di
Scienze Biologiche, Como, 19001.
198 THE ANALYSIS OF SENSATIONS
registers the experiences of the individual, decreases with
the simplification of the organism, it will naturally occur
to try whether and to what extent the behaviour of simpler
organisms can be explained solely by reference to reflexes. 1
It is not, indeed, probable that there exist any animal
organisms entirely devoid of memory and endowed with
reflexes absolutely incapable of modification, since it is
scarcely possible to draw a sharp line between the acquisi-
tions of the species and the acquisitions of the individual. 2
Still, I should consider such an attempt as well worth
making, although a critical analysis of the result would be
still more valuable.
I hope that we shall still learn a great deal for our own
psychology, not only from our children, but also from " our
younger brothers 1 ' the animals. But in order to under-
stand why man is psychically so much more than the
cleverest animal, it will be sufficient to reflect on the
acquisitions which the individual and the species have
made in the atmosphere of a social culture extending over
many thousand years.
Representation by images and ideas, therefore, has to
supply the place of sensations, where the latter are im-
perfect, and to carry to their issue the processes initially
determined by sensations alone. But in normal life,
representation cannot permanently supplant sensation,
1 Mach, Populdr-wissenchaftliche Vorlesungen, " Ueber den Einfluss
zufalliger Umstande," etc. , Leipzig, 1903, 3rd edition, pp. 294-295;
Prinzipien der Wdrmelehre, Leipzig, 1900. See the chapter on
" Sprache und Begriffe."
2 Cf. the fourth edition of this work, p. 153.
THE ANALYSIS OF SENSATIONS 199
where this is at all present, except with the greatest danger
to the organism. As a fact, there is, in normal psychical
life, a marked difference between the two species of
psychical elements. I see a blackboard before me. I
can, with the greatest vividness, represent to myself on
this blackboard, either a hexagon drawn in clear, white
lines, or a colored figure. But, pathological cases apart,
I always distinguish what I see and what I represent to
myself. In the transition to mental imagery, I am aware
that my attention is turned from my eyes, and directed
elsewhere. In consequence of this attention, the spot seen
upon the blackboard and the one represented to myself as
situated in the same place differ as by a fourth co-ordinate.
It would not be a complete description of the facts to say
that the image is superimposed on the object as the images
reflected in a transparent plate of glass are superimposed
on the bodies seen through it. on the contrary, what is
represented seems to me to be supplemented by a qualita-
tively different and opposite sensational stimulus, which
stimulus it in its turn sometimes supplants. We are con-
fronted here, for the time being, with a psychological fact,
the physiological explanation of which will sometime
undoubtedly be discovered.
It is natural to suppose that, when mental images occur,
the interaction of the organs of the nervous system causes
the repetition of organic processes partially identical with
those which were determined by the physical stimulus
on occasion of the corresponding sensations. Images
are normally distinguished from sensations by being less
intense, and above all by their instability. When I draw
a geometrical figure in imagination, it is as if the lines faded
200 THE ANALYSIS OF SENSATIONS
immediately after they are drawn, as soon as my attention
is directed to ether lines : when one comes back to them
they have vanished, and must be reproduced over again.
This is the principal reason of the advantage in point of
convenience which an actual material geometrical drawing
possesses over a merely imagined one. It is easy enough
to hold firmly before the mind a small number of lines, for
instance an arc of a circle with the angles at the centre and
circumference and a pair of coincident or intersecting sides ;
but if in this case we proceed to add the diameter drawn
through the apex of the angle at the circumference, it at
once becomes more difficult to deduce in imagination the
relative sizes of the angles, without continually renewing and
completing the figure. The power of replacing the figure
with ease and rapidity, is, however, enormously increased by
practice. When I was studying the geometry of Steiner
and Von Staudt, I was able to do this to a much greater
extent than I can now.
Where the development of intelligence has reached a high
point, such as is presented now in the complex conditions
of human life, mental images may frequently absorb the
whole of attention, so that events in the neighbor-
hood of the reflecting person are not noticed, and
questions addressed to him are not heard ; a state
which persons unused to it are wont to call absent-
mindedness, although it might with more appropriate-
ness be called present-mindedness. If the person in
question is disturbed in such a state, he has a very
distinct sensation of the labor involved in the transference
of his attention.
THE ANALYSIS OF SENSATIONS 201
It is well to note this sharp division between images
and sensations, as it is an excellent safeguard against
carelessness in psychological explanations of sense-pheno-
mena. The well-known theory of " unconscious inferences "
would never have reached its present extended development
if more heed had been paid to this circumstance.
The organ, of which the states determine images, can
provisionally be conceived as one which, in a diminished
degree, is capable of all the specific energies of the sense
and motor organs, so that the specific energy now of one,
now of another, sense-organ can play upon it, according to
the nature and direction of its attention for the time being.
Such an organ is eminently qualified to effect physiological
relations between the different energies. As is shewn by
experiments with animals whose cerebrum has been re-
moved, there are probably, in addition to the organ of
representation, a number of other analogous organs of
mediation, which are less intimately connected with the
cerebrum, and whose processes consequently do not appear
in consciousness.
That wealth of representative life with which we are
personally acquainted from self-observation, doubtless made
its first appearance with man. But the beginnings of this
ｅxpression of life, in which nothing but the relations of the
various parts of the organism to one another is manifested,
go back with no less certainty to quite primitive stages in
the animal scale. But the parts of single organs must also,
in virtue of their reciprocal tension, stand to one another
in a relation analogous to that in which the parts of the
202 THE ANALYSIS OF SENSATIONS
organism as a whole stand to one another. The two
retinae, with their motor mechanism of accommodation
and of luminous adjustment, dependent on light-sensations,
afford a very clear and familiar example of such a relation.
Physiological experiment and simple self-observation teach
us that such an organ has its own purposive habits, its own
peculiar memory, one might almost say its own intelligence.
The most instructive observations in this connexion are
probably those of Johannes Miiller, collected in his admir-
able work on " The Phantasms of Sight " ( Ueber diephantas-
tischen Gesichtserscheinungen, Coblenz, 1826). The sight-
phantasms observed by Miiller and others in the waking
state are entirely withdrawn from the influence of either
the will or the reason. They are independent phenomena,
essentially connected with the sense-organs, and charac-
terized by complete visual objectivity. They are veritable
imagination- and memory-phenomena of sense. Miiller
considers that the free individual existence of hallucinations
is a part of the life of the organism, and that it cannot be
brought under the so-called laws of association, in which
he indicates that he does not believe. It seems to me that
the continuous alteration of the phantasms, as described by
him, is no evidence against the laws of association. These
processes can, on the contrary, be conceived as recollec-
tions of slow perspectival changes in visual images. The
element of desultoriness in the common connexion of
a train of representations by way of association, only
comes in when sometimes one, and sometimes another,
THE ANALYSIS OF SENSATIONS 203
department of sensation begins to be involved (see
Chapter XL)
Those processes which (according to Miiller) are normally
induced in the "visual substance" by excitations of the
retina, and which condition the act of seeing, may also,
under exceptional conditions, be spontaneously produced
in the visual substance without excitation of the retina, and
thus become the source of phantasms or hallucinations.
We speak of sense-memory when the phantasms are closely
allied in character to objects seen before, of hallucinations
when the phantasms arise more freely and independently.
But no sharp distinction between the two cases can be
maintained.
I am acquainted with all manner of sight-phantasms from
my own experience. The mingling of phantasms with
objects indistinctly seen, the latter being partly supplanted,
is probably the most common case. In my own case, these
phenomena are particularly vivid after a tiring night's
journey in the train. Rocks and trees then assume the
most fantastic shapes. Years ago, while engrossed with the
study of pulse-tracings and sphygmography, the fine white
curves on the dark background often came up before my
eyes, in the evening or in the dim light of day, with the full
semblance of reality and objectivity. Later also, during
miscellaneous work in physics, I witnessed analogous
phenomena of "sense-memory." More rarely, images of
things which I have never seen before, have appeared before
my eyes in the daytime. Thus, years ago, on a number
of successive days, a bright red capillary net (similar to
a so-called enchanted net) shone out upon the book in
which I was reading, or on my writing paper, although
204 THE ANALYSIS OF SENSATIONS
I had never been occupied with forms of this sort. The
sight of bright-colored changing carpet patterns before falling
asleep was very familiar to me in my youth ; the pheno-
menon will still make its appearance if I fix my atten-
tion on it. one of my children, likewise, often used
to tell me that he " saw flowers " before falling asleep.
Less often, I see in the evening, before falling asleep,
various human figures, which alter without the action
of my will. on a single occasion I attempted suc-
cessfully to change a human face into a fleshless skull;
this solitary instance may, however, be an accident.
It has often happened to me that, on awaking in a
dark room, the images of my latest dreams remained
present in vivid colors and in abundant light. A
peculiar phenomenon, which has for some years frequently
occurred with me, is the following. I awake and lie
motionless with my eyes closed. Before me I see the bed-
spread with all its little folds, and upon it, motionless and
unchanging, my hands in all their details. If I open my
eyes, either it is quite dark, or it is light, but the bed-spread
and my hands lie quite differently from the manner in
which they appeared to me. This is a remarkably fixed and
persistent phantasm with me, such as I have not observed
under other conditions. As regards this image, I think that I
notice that all its parts, even those that are widely separated,
appear with equal distinctness in a way which for obvious
reasons is impossible in the case of anything objectively seen.
When I was young I used frequently to have very vivid
acoustic, and particularly musical, hallucinations on waking
up ; they have, however, become extremely rare and faint
since my interest in music has decreased. But perhaps
THE ANALYSIS OF SENSATIONS 205
the interest in music is itself a secondary effect, rather
than a cause.
When we withdraw the retina from the influence of
outward excitations, and turn the attention to the field of
vision alone, traces of phantasms are almost always present.
Indeed, they make their appearance when the outer
excitations are merely weak and indistinct, in a half-light,
or when we look at a surface covered with dim, blurred
spots, such as a cloud, or a grey wall. The figures which
we then seem to see, provided they are not produced by a
direct act of attention in selecting and combining distinctly
seen spots, are certainly not products of representation,
but constitute, at least in part, spontaneous phantasms,
which, for the time being and at some points, take forcible
precedence over the retinal excitation. In these cases
expectation seems to be favorable to the occurrence of
the phantasms. When I have been looking for interfer-
ence-bands I have very often thought that I could clearly
detect the first dull traces of them in the field of vision,
when the progress of the experiment has convinced me
that I was certainly deluded. Over and over again, in a
half-light, I have thought that I could distinctly see a jet
of water that I was expecting to come out of an india-
rubber tube, and have had to touch with my finger to
convince myself of my mistake. Such weak phantasms
seem as a rule to yield readily to the influence of the
intellect, whereas the intellect is unable to produce any
effect on strong phantasms with vivid colors. The former
are more akin to representations, the latter to sensations.
These weak phantasms, which are sometimes over-
powered by sensations, are sometimes in equilibrium
206 THE ANALYSIS OF SENSATIONS
with them, and sometimes replace them, suggest the
possibility of comparing the strength of phantasms with
the strength of sensations. Scripture has carried out this
idea. He takes an observer who thinks that he sees a
colored cross, which is really non-existent, and then causes
to appear in his field of vision a real line of intensity
increasing from zero upwards and drawn in a direction
which is not known beforehand, until the line is noticed
and given the same value as the phantasm. 1 In this way
all the transitional stages between sensation and representa-
tion can be obtained. At no point do we come upon a
psychical element that is absolutely incapable of being
compared with the sensation, which we must undoubtedly
regard as a physical object also. The way in which the
presentations are connected by association is, however,
quite different from the way in which the sensations are
connected.
Leonardo da Vinci discusses the mingling of phantasms
with objects seen (see p. 66 above) in the following words :
" I shall not omit to give a place among these directions
to a newly-discovered sort of observation, which may,
indeed, make a small and almost ludicrous appearance, but
which is, nevertheless, very useful in awakening the mind
to various discoveries. It consists in this, that thou
shouldst regard various walls which are covered with all
manner of spots, or stone of different composition. If
thou hast any capacity for discovery, thou mayest behold
there things which resemble various landscapes decked
1 Scripture, The New Psychology, London, 1897, p. 484.
THE ANALYSIS OF SENSATIONS 207
with mountains, rivers, cliffs, trees, large plains, hills and
valleys of many a sort. Thou canst also behold all
manner of battles, life-like positions of strange, unfamiliar
figures, ｅxpressions of face, costumes, - and numberless
things which thou mayest put into good and perfect form.
The experience with regard to walls and stone of this sort
is similar to that of the ringing of bells, in the strokes of
which thou willst find anew every name and every word
that thou mayest imagine to thyself.
" Do not despise this opinion of mine when I counsel
thee sometimes not to let it appear burdensome to thee to
pause and look at the spots on walls, or the ashes in the
fire, or the clouds, or mud, or other such places; thou
wilt make very wonderful discoveries in them, if thou
observest them rightly. For the mind of the painter is
stimulated by them to many new discoveries, be it in the
composition of battles, of animals and human beings, or
in various compositions of landscapes, and of monstrous
things, as devils and the like, which are calculated to bring
thee honor. For through confused and undefined things
the mind is awakened to new discoveries. But take heed,
first, that thou understandest how to shape well all the
members of the things that thou wishest to represent, for
instance, the limbs of living beings, as also the parts of a
landscape, namely the stones, trees, and the like."
All marked and independent appearance of phantasms
without excitation of the retina dreams and the half-
waking state excepted must, by reason of their biological
purposelessness, be accounted pathological. In like
manner, we are constrained to regard every abnormal
dependence of phantasms upon the will as pathological.
208 THE ANALYSIS OF SENSATIONS
Such, very likely, are the states that occur in insane
persons who regard themselves as very powerful, as God,
etc. But the delusions of the megalo-maniac can equally
be produced by the mere absence of inhibitory associations ;
for instance, one can believe in a dream that one has solved
the most tremendous problems, because the associations
that reveal the contradiction do not take place.
6.
After these introductory remarks we may now turn to the
consideration of a few physiologico-optical phenomena, the
full explanation of which, it is true, is still distant, but which
are best understood as the ｅxpressions of an independent
life on the part of the sense-organs.
We usually see with both eyes, and agreeably to definite
needs of life, not colors and forms, but bodies in space. It
is not the elements of the complex, but the whole physio-
logico-optical complex that is of importance. This complex
the eye seeks to fill out and supplement, according to the
habits acquired (or inherited) in its environment, whenever,
as a result of special circumstances, the appearance of the
complex is incomplete. This occurs oftenest in monocular
vision, but is also possible in the binocular observation of
very distant objects where the stereoscopic differences con-
sequent upon the distance of the eyes from each other vanish.
We generally perceive, not light and shadow, but objects
in space. The shading of bodies is scarcely noticed.
Differences in brightness produce differences in the sensa-
tion of depth, and help to produce the modelling of bodies
when the stereoscopic differences are insufficient for this
THE ANALYSIS OF SENSATIONS 209
purpose, a condition which is very noticeable in the
observation of distant mountains.
Very instructive, from this point of view, is the image on
the dull plate of the photographic camera. We are often
astounded at the brightness of the lights and the depth of the
shadows, which were not noticed in the bodies themselves as
long as one was not compelled to see everything in a single
plane. I remember quite well that, in my childhood, all
shading of a drawing appeared to me an unjustifiable
disfigurement, and that an outline-drawing was much more
satisfactory to me. It is likewise well known that whole
peoples, for instance the Chinese, despite a well-developed
artistic technique, do not shade at all, or shade only in a
defective manner.
The following experiment, which I made many years
ago, 1 illustrates very clearly the relation in question between
the sensation of light and the sensation of depth.
We place a visiting-card, bent crosswise before
us on the desk, so that its bent edge b e is to-
wards us. Let the light fall from the left. The
half abdev$> then much lighter, the \\d\ibcef l
much darker a fact which is, however, scarcely
perceived in unprejudiced observation. We now
close one eye. Hereupon, part of the space-sensations dis-
appear. Still we see the bent card spatially and nothing
noticeable in the illumination. But as soon as we succeed
in seeing the bent edge depressed instead of raised, the light
and the shade stand out as if painted thereon. I pass over
for the moment the perspectival reversal of the card, which
1 " Ueber die physikalische Wirkung raumlich verteilter Lichtreize,"
Sitzungsbcrichte der Wiener Akademie^ Vol. LIV., October 1866.
210 THE ANALYSIS OF SENSATIONS
can easily be explained. Such an " inversion " is possible,
because depth is not determined by a monocular image. If
in Fig. 25, i O represents the eye, a b c a section of a bent
card, and the arrow the direction of the light, ab will
appear lighter than be. Also in 2, a b will appear lighter
than b c. Plainly, the eye must acquire the habit of varying
the fall in the sensation of depth concomitantly with the
change in brightness of the surface-elements that it sees.
The fall and the depth diminish, with diminishing illumina-
tion, towards the right, when
the light falls from the left (i) ;
contrariwise, when it falls from
the right. Since the wrappings
of the bulb in which the retina
is embedded are translucent, it
is not a matter of indifference
for the distribution of light
upon the retinae whether the
light falls from the right or the
left. Accordingly, things are so
arranged that, without any aid of the judgment, a fixed
habit of the eye is developed, by means of which illumina-
tion and depth are connected in a definite way. If now, by
virtue of another habit, it is possible to bring a part of the
retina into conflict with the first habit, as in the above experi-
ment, the effect is made manifest in remarkable sensations.
Certain experiments of Fechner's have shewn how im-
portant the effect of the light that penetrates through the
wrappings of the bulb can become. 1 one observation in
1 Feclmer, " Ueber den seitlichen Fenster- und Kerzenversuch,"
Berichte der Leipziger Gesellschaft der Wissensckaf/en, 1860.
Fig. 25.
THE ANALYSIS OF SENSATIONS 211
this connexion is as follows. Beneath my writing-table
is a grey-green rug, a small piece of which I can see as
I write. Now, when a double image of this bit arises,
accidentally or intentionally, when the sunlight or daylight
comes from the left, the image belonging to the left, or
more strongly illuminated eye, is a vivid green by contrast,
while the image on the right side is quite dull in color.
It would be interesting to study the variation of intensity
and color of the illumination of the bulb in the case of
these images and in experiments in inversion.
The purpose of the preceding remarks is merely to
point out the character of the phenomenon under con-
sideration and to indicate the direction in which a physio-
logical explanation (exclusive of psychological speculation)
is to be sought. We will further remark that, with respect
to interchangeable qualities of sensation, a principle similar
to that of the conservation of energy seems to hold.
Differences of brightness are partly transformed into differ-
ences of depth, and themselves become weaker in the
process. At the expense of differences of depth, on
the other hand, differences of brightness may be
augmented. An analogous observation will be made
later on in another connexion.
The habit of observing bodies as such, that is, of giving
attention to a large and spatially cohering mass of light-
sensations, is the cause of peculiar and often surprising
phenomena. A two-colored painting or drawing, for
instance, appears in general quite different according as we
212 THE ANALYSIS OF SENSATIONS
take the one or the other color as the background. The
puzzle pictures, in which, for example, an apparition makes
its appearance between tree-
trunks as soon as the dark
trees are taken as the back-
ground, and the bright sky as
the object, are well known.
In exceptional instances only
do background and object
possess the same form a
configuration frequently em-
ployed in ornamental designs,
as may be seen in Fig.
26, taken from p. 15 of the
above - mentioned Grammar
of Ornament^ also in Figs. 20
and 22 of Plate 45, and in
Fig. 13 of Plate 43 of that work.
Pig. 26.
The phenomena of space-vision which accompany the
monocular observation of a perspective drawing, or, what
amounts to the same thing, the monocular observation of
an object, are generally very lightly passed over, as being
self-evident in nature. But I am of the opinion that there
is yet much to be investigated in these phenomena. one
and the same image in perspective may represent an
unlimited number of different objects, and consequently
the space-sensation can be only in part determined by such
a drawing. If, therefore, despite the many bodies conceiv-
THE ANALYSIS OF SENSATIONS 213
able as belonging to the figure, only a few are really seen
with the full character of objectivity, there must exist some
good physiological reason for the fact. It cannot arise from
the adducing of auxiliary considerations in thought, nor from
the awakening of conscious remembrances in any form, but
must depend on certain organic life habits of the visual sense.
If the visual sense acts in conformity with the habits
which it has acquired under the conditions of life of the
species and the individual, we may, in the first place,
assume that it proceeds according to the principle of prob-
ability ; that is, those functions which have been most
frequently excited together before, will afterwards tend to
make their appearance together when only one is excited.
For example, those particular sensations of depth which in
the past have been most frequently associated with a given
perspective figure, will be readily reproduced again when
that figure makes its appearance, although not necessarily
co-determined thereby. Furthermore, a principle of
economy appears to manifest itself in the observation of
perspective drawings ; that is to say, the visual sense never
of itself burdens itself with any greater effort than is
demanded by the stimulus. The two principles coincide
in their effects, as we shall presently see.
The following may serve as a detailed illustration of the
above. When we look at a straight line in a perspective
drawing, we always see it as a straight line in space,
although the straight line, qua perspective drawing, may
correspond to an unlimited number of different plane
214 THE ANALYSIS OF SENSATIONS
curves, qua objects. But only in the special case where
the plane of a curve passes through the centre of one
eye, will it be reproduced on the retina in question as a
straight line (or as a great circle), and only in the yet more
special case where the plane of the curve passes through
the centres of both eyes, will it be reproduced as a straight
line for both eyes. It is thus extremely improbable that a
plane curve should ever appear a straight line, while on the
other hand a straight line in space is always reproduced on
both retinae as a straight line. The most probable object,
therefore, answering to a straight line in perspective, is a
straight line in space.
The straight line has various geometrical properties.
But these geometrical properties, for example the familiar
characteristic of being the shortest distance between two
points, are not physiologically of importance. It is of
far more consequence that straight lines lying in the
median plane or perpendicular thereto are physiologically
symmetrical to themselves. A vertical lying in the median
plane is also physiologically distinguished by its perfect
uniformity of depth-sensation, and by its coincidence with
the direction of gravity. All vertical straight lines may be
readily and quickly made to coincide with the median plane,
and consequently partake of this physiological advantage.
But the spatial straight line generally, must be physiologi-
cally distinguished by some further mark. Its sameness of
direction in all its elements has already been pointed out.
In addition to this, however, it is to be noted that every
point of a straight line in space marks the mean of the
depth-sensations of the neighboring points. Thus the
straight line in space gives a minimum of departure from
THE ANALYSIS OF SENSATIONS 215
the mean of the depth-sensations, just as every point on
the straight line gives the mean of the similar space-values
of the adjacent points; and the assumption forthwith
presents itself that the straight line is seen with the least
effort. The visual sense acts therefore in conformity with
the principle of economy, and, at the same time, in con-
formity with the principle of probability, when it exhibits
a preference for straight lines.
As early as 1866, I wrote, in the Proceedings of the
Vienna Academy ', Vol. 54 : " Since straight lines every-
where surround civilized human beings, we may, I think,
assume, that every straight line which can possibly be
produced upon the retina has been seen numberless times,
in every possible way, spatially as a straight line. The
efficiency of the eye in the interpretation of straight lines
ought not, therefore, to astonish us." Even then I wrote
this passage (opposing the Darwinian view,- which I sup-
ported in the same paper) half-heartedly. To-day I am
more than ever convinced that the efficiency referred to
is not the result of individual practice, nor indeed of
human practice at all, but that it is also characteristic of
animals, and is, at least in part, a matter of inheritance.
10.
The deviation of a sensation from the mean of the
adjacent sensations is always noticeable, and exacts a
special effort on the part of the sense-organ. Every new
turn of a curve, every projection or depression of a surface,
involves a deviation of some space-sensation from the
mean of the surrounding field on which the attention is
2i6 THE ANALYSIS OF SENSATIONS
directed. The plane is distinguished physiologically by
the fact that this deviation from the mean is a minimum,
or for each point in particular = o. In looking through a
stereoscope at a spotted surface, the separate images of
which have not yet been combined into a binocular image,
we experience a peculiarly agreeable impression when the
whole is suddenly flattened out into a plane. The aesthetic
impressions produced by the circle and the sphere seem
to have their source mainly in the fact that the above-
mentioned deviation from the mean is the same for all
points.
1 1.
That the deviation from the mean of the environment
plays a r61e in light-sensation I pointed out many years
ago. 1 If a row of black and white sectors, such as are
shown in Fig. 27, be painted on a strip of paper AABB^
and this be then wrapped about a cylinder the axis of
which is parallel to AB, there will be produced, on the
rapid rotation of the cylinder, a grey field with increasing
illumination from B to A, in which, however, a brighter
line a a, and a darker line /3 /3, make their appearance.
The points which correspond to the indentations a are
not physically brighter than the neighboring parts, but
their light-intensity exceeds the mean intensity of the
immediately adjacent parts, while, on the other hand, the
1 " Ueber die Wirkung der raumlichen Vertheilung des Lichtreizes auf
die Netzhaut," Sitzungsberichle der Wiener Akademie (1865), Vol.
LII. Continuation of the same inquiry: Sitzber. (1866), Vol. LIV. ;
Sitzber. (1868), Vol. LVII. ; Vierteljahrsschrift fur Psychiatrie,
Neuwied- Leipzig, 1868 (" Ueber die Abhangigkeit der Netzhautstellen
von einander ").
THE ANALYSIS OF SENSATIONS 217
light-intensity at /3 falls short of the mean intensity of the
adjacent parts. 1 This deviation from the mean is thus
distinctly felt, and accordingly imposes a special burden
upon the organ of sight. on the other hand a continuous
change in brightness is scarcely noticed, as long as the
brightness of each particular point corresponds to the mean
of the adjacent points. Long ago I drew attention to the
important teleological bearing of this fact on the saliency
and the delimitation of objects (Sitzungsberichte der Wiener
Akademie October 1865, and January 1868). Small
differences are slurred over by the retina, and larger
A A
Fig. 27.
differences stand out with disproportionate clearness.
The retina schematizes and caricatures. At an even
earlier period the important part which outlines play in
vision had been noticed by Panum.
A series of very various experiments, of which that repre-
sented in Fig. 27 is one of the simplest, led me to the
conclusion that the illumination of a position on the retina
is felt in proportion to its deviation from the mean of the
1 A remark concerning the analogies between light-sensation and
the potential function will be found in my note " Ueber Herrn
Gu6bhards Darstellung der Aequipotentialkurven," Wiedemann's
Annalen, 1882, Vol. XVII., p. 864; and see my Prinzipien der
Warmelehre, 2nd edition, 1900, p. 118.
218 THE ANALYSIS OF SENSATIONS
illuminations of the adjacent positions. The value of the
retinal positions in determining this mean is to be conceived
as rapidly decreasing with their distance from the position
under consideration, a fact which of course can only be
explained as depending on an organic reciprocal action of
the retinal elements on one another. Let i=f (x, y) be
the intensity of illumination of the retina with reference to
a system of co-ordinates (XY); then the mean value deter-
mining the intensity for a given position may be symbolically
represented as approximately
where m is constant, and the radii of all curves of the
surface / (x, y) are taken as large in proportion to the
distance at which the retinal positions are still perceptibly
influenced. Now according as f_I+_lji s positive or
negative, the position on the retina experiences a darker or
a brighter sensation respectively than it does under equal
illumination of the adjacent positions with the intensity
corresponding to itself. If the surface / (x, y) has edges
and indentations, ( a4-~T ] becomes infinite, and the
\ 4& <y 2 /
formula is useless. In this case, however, a marked increase
of darkness or brightness corresponds to the indentation,
though of course not an infinite increase or decrease. The
increase or decrease, again, are not denned by a hard and
fast line, but fade gradually away, as we should expect from
the principle of deviation from the mean. For the retina
consists, not of sensitive points, but of an infinite number
of sensitive elements of finite extension. As regards the
THE ANALYSIS OF SENSATIONS 219
law of the reciprocal action of these elements, we still do
not know it accurately enough to enable us to determine
precisely the phenomena of this special case.
It is easy to go wrong in judging of the objective distri-
bution of light according to the subjective impression, and
consequently a knowledge of the above-mentioned law of
contrast is important even for purely physical researches.
Thus Grimaldi was deceived by a phenomenon of this kind.
We come across the same phenomenon in the investigation
of shadows, and of spectral absorption, and in countless
other cases. Peculiar circumstances prevented my papers on
this subject from becoming generally known, and the relevant
facts were discovered for the second time thirty years later. 1
It may seem surprising that, in addition to /, the second
differential quotients of *, but not the first, , , seem
dx oy
to influence the sensation of brightness. We scarcely notice
a regular and continuous rise in the intensity of illumination
of a surface, for instance, in the direction x t and special
devices are necessary to convince one that there is a rise.
on the other hand, these first differential quotients exercise
an influence on the modelling, on the plastic quality,
1 H. Seeliger, " Die scheinbare Vergrosserung des Erdschattens bei
Mondfinsternissen," Abhandlungen der Munchener Akademie^ 1896 ;
H. Haga and C. H. Wind, " Beugung der Rontgenstrahlen," Wiede-
mann's Annalen, Vol. LXVIII., 1899, p. 866; C. H. Wind, "Zur
Demonstration einer von E. Mach entdeckten optischen Tauschung,"
Riecke and Simon's Physikalische Zeitschrift^ I., No. 10. A. von
Obermayer (" Ueber die Saumeum die Bilder dunkler Gegenstande auf
hellem Hintergrunde," Eder's Jahrbiich der Photographic ; 1900) pub-
lished a number of new facts which can be explained on the law of
contrast laid down in the text. But, of my four papers, he is only
acquainted with the first, and consequently states the law in its earlier
defective form.
220 THE ANALYSIS OF SENSATIONS
of the surface seen. Call the horizontal direction x, and
the distance as regards depth of a point on the illuminated
surface r ; then and ^ are parallel. This ｅxpression,
which of course is only to be understood symbolically,
means that we have the representation of a cylindrical
surface with vertical generatrix and plane horizontal
directrix r = F (jc), of which the second differential
<y 2 r
quotients ^ (curvatures) are parallel to the first differential
oOC
quotients, the rises in intensity of illumination. The
tracing of the curve is determined by the accessory circum-
stances indicated on p. 210.
12.
With regard to the depth-sensations excited by a
monocular image, the following experiments are instructive.
Fig. 28 is a plane quadrilateral with its two diagonals. If
we regard it monocularly, it is most easily
seen, according to the laws of probability
and economy, as a plane. In the great
majority of cases, objects which are not
plane, force the eye to the vision of depth.
^ . - Where this compulsion is lacking, the plane
^^^ object is the most probable and at the same
Fg. 28. time the most convenient for the organ of
sight.
The same drawing may be also viewed monocularly as a
tetrahedron, the edge b d of which lies in front of a c, or as
a tetrahedron, the edge b d of which lies behind a c. The
THE ANALYSIS OF SENSATIONS 221
influence of the imagination and the will upon the visual
process is extremely limited ; it is restricted to the directing
of the attention and to the selection of the appropriate dis-
position of the organ of sight for one of a number of cases
given by habit, of which, however, each one, when chosen,
takes its place with mechanical certainty and precision.
Looking at the point e y we can, as a fact, produce either of
the two optically possible tetrahedrons at will, according as we
represent to ourselves b d as nearer or farther away than a c.
The organ of sight is practised in the representation of these
two cases, since it often happens that one body is partly
covered by another.
Loeb I thinks that the act of bringing Fig. 3 1 nearer to
the eyes gives rise to short-distance accommodation, and
thereby also to our seeing the fixed edge b e as raised. I
have not been able to obtain any such definite result myself,
nor can I find any sufficient theoretical ground for it, 2
although I readily admit that changes in the distance of the
figure easily lead to changes in our view of it.
The same figure may, finally, be seen as a four-sided
pyramid, if we imagine the conspicuously situated point of
intersection e before or behind the plane abed. This is
difficult to do, lib e d and a e c are two perfectly straight
lines, because it conflicts with the habit of the organ of
sight to see, without constraint, a straight line bent; the
effort is successful only because the point e has a con-
1 Loeb, " Ueber optische Inversion," Pfliiger's Archiv, Vol. XL.,
1887, p. 247.
2 Hillebrand (" Verhaltnis von Akkommodation und Konvergenz
zur Tiefenlokalisation," Zeitschrift fur Psychologic und Physiologic der
Sinnesorgane, Vol. VII., p, 97) has proved the slight importance which
accommodation has for the seeing of depth.
222 THE ANALYSIS OF SENSATIONS
spicuous position. But if there is a slight indentation at e,
the attempt involves no difficulty.
The effect of a linear perspective drawing is felt as
unerringly by one who is ignorant of perspective as by
one who is thoroughly conversant with the theory, provided
he is able to disregard the plane of the drawing, a con-
dition readily fulfilled in monocular observation. Reflexion,
and even the remembrance of seen objects, have, according
to my belief, little or nothing to do with the effect in
question. Why the straight lines of a drawing are seen as
spatial straight lines, has already been pointed out. Where
straight lines appear to converge to a point
in the plane of the drawing, the converging
or approaching ends are transferred, accord-
ing to the principles of probability and
economy, to like or to nearly like depth.
This gives us the effect of vanishing points.
Fig. 29.
It is possible to see such lines as parallel,
but there is no necessity for such an impression. If we
hold the drawing, Fig. 29, on a level with the eye, it may
represent to us a glance down a passage-way. The ends
ghef are transferred to like distances. If the distance
is great, the lines ae^bf^cg^dh appear horizontal. If we
raise the drawing, the ends efgh rise, and the floor abef
seems to have an upward slope. Upon lowering the draw-
ing, the opposite phenomenon is presented ; and analogous
changes may be observed by moving the drawing towards
the right or the left. In these facts, the elements of per-
spective effect find simple and clear ｅxpression.
Plane drawings, provided they consist entirely of straight
lines, everywhere intersecting each other at right angles,
THE ANALYSIS OF SENSATIONS 223
almost always appear plane. If oblique intersections and
curved lines occur, the lines easily pass out of
the plane ; as is shown, for example, by Fig. 30^
which may, without difficulty, be conceived as
a curved sheet of paper. When outlines, such
as are represented in Fig. 30, have assumed
definite spatial form, and are seen as the
IR 30.
boundary of a surface, the latter, to describe
it briefly, appears as flat as possible, that is to say, is
presented with a minimum of deviation from the mean
of the depth-sensation. 1
The peculiar reciprocal action of lines intersecting
obliquely in the plane of the drawing (or on the retina),
whereby such lines are mutually forced out of the plane of
the drawing (or out of the plane perpendicular
to the line of sight) was first observed by me
on the occasion of the above-mentioned (p. 209)
experiment with the monocular inversion of a
card. The card in Fig. 31, whose edge b e
when turned outwards towards me is in a
vertical position, assumes, when I succeed in
seeing b e depressed, a recumbent position, like that of a
book lying open upon my table, with the result that b
appears further away than e. When one is once acquainted
with this phenomenon, the inversion may be performed
1 Here again, the depth-sensation resembles the potential function,
in a space at the boundaries of which it is determined. This flat-as-
possible surface does not coincide with the surface of minimal area,
which would be obtained if the spatial outlines were made of wire, and
then dipped in soap-suds, producing a Plateau's liquid film.
224 THE ANALYSIS OF SENSATIONS
with almost every object, and one can always observe along
with the change of form or tilting over, this remarkable
simultaneous change of position. The effect is especially
astonishing in the case of transparent objects. Let abed
be a section of a glass cube lying on a table / /, and let O
be the eye (Fig. 32). on monocular inversion, the angle
a is projected to a 1 ', b to the nearer point V ', t to </, and
d to d'. The cube will seem to stand obliquely on its edge
c f upon the table t' /'. In order that the drawing might
afford a better survey of the
phenomenon, the two images
have been represented behind,
not within one another. If a
drinking-glass partly filled with
a colored liquid be substi-
tuted for the cube, it will be
seen, together with the surface
of the liquid, in a similar oblique position.
With sufficient attention, the same phenomena may be
observed with any linear drawing. If we place the page
containing Fig. 31 vertically before us, and
observe it monocularly, we shall see b project
if b e be raised, but if b e be depressed b will
retreat and e will project and come nearer to
the observer. Loeb l notices that when this
happens the points a e remain in the plane
of the drawing. And, in fact, this makes the
change of direction intelligible. If we draw
the dotted lines, as in Fig. 3 2 A, and imagine the figure,
so far as it lies outside the dotted triangle, obliterated, we
1 Loeb, " Ueber optische Inversion," quoted p. 221 above.
Fig 32
THE ANALYSIS OF SENSATIONS 225
are left with the image of a hollow or raised three-sided
pyramid, which lies with its base in the plane of the draw-
ing. Inversion no longer produces any sort of mysterious
change of position. It would seem, therefore, that every
point seen monocularly aims at the minimum deviation
from the mean of the sensation of depth, which is attainable
under the conditions of the experiment, and that the whole
object seen aims at the minimum attainable amount of
removal from Hering's nucleus-surface.
When we consider the deformations which a plane
rectilinear figure undergoes when traced in monocular
space, all such deformations may be qualitatively reduced
to the following principle : the legs of an acute angle are
thrust out on opposite sides of the plane of the drawing, or
of the plane perpendicular to the line of sight, and the legs
of an obtuse angle are thrust out on the same side. In
this process acute angles are magnified and obtuse angles
diminished. All angles tend to become right angles.
14.
This principle suggests that the phenomenon just
described is closely related to Zollner's pseudoscopy and the
numerous phenomena connected with it. Here again
everything turns on the apparent enlargement of acute and
the apparent reduction of obtuse angles, except that the
drawings are seen in the plane. But when they are seen in
monocular space the pseudoscopic effects vanish, and the
phenomena described above appear. Now although these
phenomena have been much studied, no completely
satisfactory explanation of them has as yet been offered.
Naturally such superficial explanations as, for instance, the
226 THE ANALYSIS OF SENSATIONS
assumption that we are chiefly accustomed to see right
angles, are inadmissible, if the investigation is not utterly to
miscarry or to be prematurely broken off. We see oblique-
angled objects often enough, but never, without artificial
preparation, the surface of a liquid at rest and yet oblique,
as we did in the experiment given above. Yet, the eye, it
would seem, prefers the oblique liquid surface to an oblique-
angled body.
The elemental power displayed in these processes has, I
believe, its root in far simpler habits of the organ of sight,
habits whose origin doubtless antedates the civilized life of
man. I once tried to explain the phenomena in question
by a contrast of directions analogous to the contrast of
colors, but without arriving at a satisfactory result. But
more recent researches by Loeb, 1 Heymans, 2 and others,
and observations by Hoefler 3 on curve-contrasts, are very
much in favor of a theory of contrast. Moreover, quite
lately at any rate, there is a decidedly increased tendency to
adopt some purely physiological explanation. 4
The principle of economy, again, has afforded me no
enlightenment as far as Zollner's pseudoscopy is concerned.
A somewhat greater prospect of success seems to be
offered by the principle of probability. Let us conceive
the retina as a perfect sphere and imagine the eye fixed
upon the vertex of an angle a in space. The planes passing
through the centre of the eye and the lines containing the
angle, project these lines upon the retina, describing thereon
1 Loeb, Pfluger's Archiv, 1895, p. 509.
2 Heyman's Zcitschrift fttr Psychologic und Physiologic dcr Sinncs-
organe, Vol. XIV., p. 101.
3 Hoefler, Ibid., Vol. XII., p. i.
4 Witasek, Ibid., Vol. XIX,, p. I.
THE ANALYSIS OF SENSATIONS 227
a spherical segment having the angle A, which represents the
angle of the monocular image. Now an infinite number of
values for a, varying from o to 180, may correspond
to a constant value of A, as will be seen if we reflect that
the lines including the objective angle may assume every
possible position in the planes of their projection. Conse-
quently, to a seen angle A, we may have corresponding all
the possible values of the objective angle a that
can be obtained by causing each of the sides, b
and c, of the triangle to vary between o and
1 80. The actual result is, supposing the calcula-
tion to be performed in a definite manner, that
larger angles are the most probable objects
corresponding to observed acute angles, and
smaller angles the most likely counterparts of
observed obtuse angles. I was not, however,
in a position to determine whether those cases,
which we are inclined to regard as geometrically equally
probable, ought also to be regarded as physiologically
equally probable a question which is both essential
and important. Moreover, the whole conception has a
much too artificial cast for me.
I cannot refrain from mentioning here the attempt which
has been made by A. Stohr to reach an explanation of the
phenomena described above from an entirely new point of
view. With the general considerations by which he was
guided I am in full sympathy and agreement. on the other
hand, I have not yet been able to convince myself that there
is a demonstrable foundation of fact corresponding to his
228 THE ANALYSIS OF SENSATIONS
hypotheses. Moreover, the relations which he presupposes
are so complicated that it is not easy to decide this question,
without thoroughly covering the ground experimentally
oneself. I therefore do not know whether Stohr's views
will amount to a complete explanation on all points. In
one of his less recent works * the assumption is made that
to the dioptric image of the eye in front of the retina,
there corresponds a catoptric image in the retina, the
latter having relief in proportion to the depth of the former.
Depth in the retina is thus both the determining factor for
the sensation of depth in visual space, and the regulating
factor in accommodation. As a matter of fact, I have always
asked myself what the means could be by which the
direction of change of accommodation is determined ; for
change of accommodation cannot be determined merely by
the magnitude of the circle of dispersion ; also there is only
a loose connection between accommodation and conver-
gence, and moreover a single eye by itself is accommodated.
Against this view, on the other hand, must be set the
numerous observations which have been made as to the
worthlessness of accommodation for the sensation of depth.
The great thickness of the retina in the eyes of insects 2
suggests, again, that the perception of relief may be con-
nected with some function of the retina.
In two later works 3 he goes further, taking this theory as
a basis. In the second of these books we find a view not
unlike Scheffler's, but in a more physiological form. The
1 Zur nativistiscken Behandhmg des Tiefensehens, Vienna, 1892.
2 Exner, Die physiologic der facettierten Augen, p. 188, Vienna, 1891.
3 Zur Erklamng der Zollnerschen Pseiidoskopie, Vienna, 1898 ; Bino-
kulare Figurmischimg und Pseudoskopie, Vienna, 1900.
THE ANALYSIS OF SENSATIONS 229
dominant view, according to which the images of positions
which deviate more or less from the corresponding positions
are fused into one unified impression, Stohr thinks is unten-
able. "Where is the pointsman who arranges the change
in such a way that, not only in extraordinary cases, but also
as of set purpose, two stimuli may be brought into com-
bination in the central organ over a quite unfamiliar pair of
lines of conduction?" It is assumed that the retinae of
both eyes naturally endeavour to minimalize the light-
stimulus, and thus tend towards the equalization of unequal
images. The nervous elements excite the ciliary muscle,
doing this not only in a quite regular and uniform manner,
but also, according to requirements, with great irregularity.
Regular contraction of the ciliary muscle produces a greater
bulging of the lens and slight contraction of the retina. If
in this process the retinal elements carry their position-values
with them, the same retinal image appears enlarged. In
this way, according to Stohr, we can understand why
Panum's proportional systems of circles (up to circles with
radii in the proportion of 4 to 5) are seen, in virtue of the
mutual adaptation of the two eyes, with identical parts of
the retina, as simple and as having a size which is the mean
of their sizes. By depicting one system in red and the
other in green points alternately, so that in the united
binocular image the red points appear between the green,
Stohr proves that the fusion of the systems of circles is not
caused by the suppression of one of the images. And
irregular contraction of the ciliary muscle is supposed to
produce various effects, (i) an irregular deformation ot
the lens with very various displacements of the apices of
the diacaustic of different pencils of rays, whereby change
230 THE ANALYSIS OF SENSATIONS
in the relief of the dioptric and catoptric images is pro-
duced ; and (2) various minimal deformations of the retina.
Stohr thinks that he can demonstrate the possibility of his
theory by detailed calculations, and that he can prove the
actuality of his presuppositions by investigating subjects
with eyes in which the crystalline lens is absent or out of its
proper position (aphakia). In any case his theory has led
to experiments with surprising results, for instance, the
stereoscopic indentation of straight lines, and, if only on
that account, it deserves to be considered with respect. But
although his whole conception of the eye and its parts as
living organisms is extremely congenial to me, I have not
yet been able to convince myself that the assumptions
which he makes in order to explain more complicated cases
of spatial vision everywhere fulfil their purpose. 1
Stohr's departure from the traditions of physiological
optics is very great. In itself this can be no reason for
refusing to test his theory closely, especially since S. Exner's
and Theodor Beer's 2 researches in comparative physiology,
which have been so rich in beautiful and remarkable results,
have made us familiar with eyes characterized by a com-
plexity and variety of organic adaptation such as a physicist
would scarcely have supposed possible a priori. It is
possible that Stohr's views may apply to other organs of
vision, although perhaps not to the human eye.
1 The following book has subsequently appeared : A. Stohr, Grund-
fragen der psychc-physiologischen Optik, Leipzig and Vienna, 1904.
The problems in question are here discussed further.
- Th. Beer, " Die Akkommodation des Fischauges," Pfliiger's
Archiv Vol. LVIIL, p. 523 ; " Akkommodation des Auges in der
Tierreihe," Wiener klinische Wochenschrift, 1808, No. XLII. ;
" Ueber primitive Sehorgane," Ibid., 1901, Nos. XL, XII., XIII.
THE ANALYSIS OF SENSATIONS 231
There are many phenomena that make it probable that
the act of sight involves other processes of change in the
eye which still require to be investigated. Stereoscopic
images with prominent stereoscopic differences display,
when they are gazed at for a long time, an enormous increase
in the growth of their relief by successive stages, even
though fusion has apparently been complete for some time.
Wave-like curvatures and swellings have been observed in
systems of fine, smooth, parallel lines, and these have been
explained in a rather peculiar manner as referable to the
incapacity of the mosaic-like texture of the retina to re-
produce straight lines of such fineness. I have, however,
always noticed this phenomenon when I have gazed for
some time at systems of straight lines which are clearly
visible and by no means micrometric. Thus the mosaic of
the retina can have nothing to do with the matter. I
should prefer to suppose that the exertion involved, perhaps
by means of small displacements in Stohr's sense, intro-
duces a certain disorder into the space-values. 1
16.
The ease of the transition from the process of seeing
plane figures pseudoscopically to that of seeing them
monocularly in space will probably help us to throw light
upon the former. This conjecture is confirmed by the
following facts. A plane linear drawing, monocularly ob-
served, usually appears plane. But if the angles be made
1 " Ueber die physiologische Wirkung raumlich verteilter Lichtreize,"
Wiener Sitzungsberichte, 2nd part, October 1866, pp. 7, 10, of the off-
print.
232 THE ANALYSIS OF SENSATIONS
to vary and motion be introduced, every drawing of this
sort will assume a solid form. We then generally see a
solid body in rotation, such as I have described on a former
occasion. 1 The well-known vibrating acoustic figures of
Lissajous, which on varying their difference of phase,
appear to lie on a revolving cylinder, afford a beautiful
example of the process in question.
Here, again, reference might be made to our habit of
constantly dealing with solid bodies. In fact, solid bodies
engaged in revolutions and turnings continually surround
us. Indeed, the whole material world in which we move
is, to a certain extent, a single solid body ; and without
the help of solid bodies we could never attain to the con-
ception of geometrical space. We do not generally notice
the position of the single points of a body in space, but
apprehend its dimensions directly. Herein lies, for the
unpractised, the main difficulty of drawing a perspective
picture. Children, who are accustomed to seeing bodies
in their real dimensions, do not understand perspective
foreshortenings, and are far better satisfied with simple
outlines or silhouettes. I can well remember this condition
of mind, and through this remembrance am able to com-
prehend the drawings of the ancient Egyptians, which
represent all parts of the body as far as possible in their
true dimensions, thus pressing them, as it were, into the
plane of the drawing, as plants are pressed in a herbarium.
In the Pompeian wall-paintings, too, we still meet with
a perceptible dislike for foreshortening, although here
the sense of perspective is already manifest. The old
1 " Beobachtungen iiber monokulare Stereoskopie," Sitzungsberichte
der Wiener A kademie (1868), Vol. LVIII.
THE ANALYSIS OF SENSATIONS 233
Italian masters, on the other hand, in the consciousness of
their perfect mastery of the subject, often amuse themselves
with excessive and sometimes even unbeautiful foreshorten-
ings, which occasionally demand considerable exertion of
the eye.
There can be no question, therefore, but that we are
much more familiar with the process of seeing solid bodies
with the distances between their salient points unchanged,
than with the process of separating out their depth, which
is always the result, in the first place, of deliberate analysis.
Accordingly, we may expect that wherever a coherent mass
of sensations, which, in virtue of its continuous transitions
and its common coloring, merged into a unity, exhibits
spatial alteration, the change will be seen preferably as the
motion of a solid body. I must confess, however, that this
way of looking at the matter does not satisfy me. I believe,
rather, that here, too, an elementary habit of the organ of
sight is at the root of the matter, a habit which did not
originally arise through the conscious experience of the
individual, but, on the contrary, antecedently facilitated
our apprehension of the movements of solid bodies. If
we should assume, for example, that every diminution of
the transverse dimension of an optical sensation-mass to
which the attention was directed had the tendency to induce
a corresponding augmentation of the dimension of depth,
and vice versa, we should have a process quite analogous
to that which we have already considered above (p. 199)
and which was compared with the conservation of energy.
This view is certainly much simpler and supplies an equally
234 THE ANALYSIS OF SENSATIONS
adequate explanation. Furthermore, it enables us to
comprehend more easily how such an elementary habit
could be acquired, how it could find ｅxpression in the
organism, and how the disposition towards it could be
inherited.
As a sort of counterpart to the rotation of solid bodies
exhibited to us by the organ of sight, I will cite here an
additional observation. If an egg, or ellipsoid with dull,
uniform surface be rolled over the top of a table, but in
such manner that it does not turn about its axis of genera-
tion, but performs jolting movements, we shall fancy
we see, on viewing it binocularly, a liquid body, or large
oscillating drop. The phenomenon is still more noticeable
if the egg, with its longitudinal axis in a horizontal position,
be set in moderately rapid rotation about a vertical axis.
This effect is immediately destroyed when marks, whose
movements we may follow, are made upon the surface of
the egg. A rotating solid body is then seen.
The explanations offered in this chapter are certainly
far from complete, yet I believe that the considerations
adduced will have some effect in stimulating and preparing
the way for a more exact and thorough study of these
phenomena.
XI. SENSATION, MEMORY AND
ASSOCIATION.
I.
THE foregoing discussions have shewn beyond all
possible doubt that out of mere sensations no
psychical life resembling ours even in the remotest degree
could be constituted. When a sensation is forgotten the
moment after it has vanished, the only possible result is a
disconnected mosaic and series of psychic states, such as
we have to suppose in the case of the lowest animals and
the most degraded idiots. At this stage, a sensation which
does not have some such effect as to stimulate violently
to movement a sensation of pain, for instance will
scarcely receive attention. For instance, the sight of a
vividly-colored spherical body, which is not supplemented
by a memory of smell and taste, by memory, in a word,
of the properties of a fruit and the experiences connected
with a fruit, remains unintelligible and is devoid of interest,
in the manner that has been observed in " psychic blind-
ness." The storing up and connexion of memories, and
their power to evoke one another, in short, Memory
and Association, are the fundamental requirements of a
developed psychical life.
What is memory? A psychical event leaves psychical
traces behind it, but it also leaves physical traces. Physi-
cally, as well as psychically, a child that has been burnt, or
235
236 THE ANALYSIS OF SENSATIONS
stung by a wasp, behaves in quite a different way from a
child that has not had this experience. For the psychical
and the physical are different only according to the way
in which they are regarded. Nevertheless it is extremely
difficult to discover in the physical phenomena of the
inorganic world characteristics having any affinity to memory.
In the physics of the inorganic world everything seems
to be determined by the circumstances of the moment, and
the past seems to be entirely without any influence. The
oscillations of a pendulum are equal, whether it is perform-
ing its first oscillation or whether 1000 others have already
taken place. Hydrogen combines with chlorine in the
same way, no matter whether it was previously in combina-
tion with bromine or with iodine. There are indeed, even
in the physical sphere, cases in which the influence of the
past is clearly expressed. The earth reveals to us the
history of its geological past, and the moon does the same.
My friend E. Suess has shewn me a piece of rock marked
with a system of very peculiar congruent parallel fissures,
which he very plausibly interprets as a prehistoric seismogram.
A wire notices, so to speak, during a considerable time,
every torsion that it sustains. Every spark of a discharge
is an individual, and is influenced by the discharges that
have preceded it. The insulating layer of the Leyden jar
preserves a history of all the previous charges.
The apparent contradiction is solved when we remember
how in physics we are accustomed to idealize and
schematize in an extreme degree the cases under considera-
tion, always presupposing the simplest possible circum-
stances. If we assume a mathematical pendulum, then no
doubt the thousandth oscillation is as the first, and no
THE ANALYSIS OF SENSATIONS 237
traces of the past are visible, precisely because we disregard
such traces. But a real pendulum wears away -its knife-
edge, and is heated by internal and external friction, so that
no oscillation, accurately considered, is exactly like any
other. The result of every second and third torsion of a
wire is somewhat different from what it would have been
if there had been no previous torsions. If a similar
schematization were possible in psychology, we should have
men who behave identically and do not betray any of the
influence of individual experiences.
In reality every psychical process leaves indelible traces
behind, just as every physical process does. In both
spheres there are irreversible processes : entropy increases,
or the bond of a friendship that has been broken, and then
renewed, is felt. And every real process contains at any
rate some irreversible components.
Now it will be said, and with justice, that traces of the
past are still far from being the same thing as memory.
As a matter of fact, what is required to increase the
resemblance is, that processes which have taken place in
the past should be set up afresh by some slight impulse.
Old violins that have been well played on, Moser's
electrical images (that come out when breathed upon),
and the phonograph, afford rather better examples. Still,
violins and phonographs have to be played by external
forces, while human beings and their memories play them-
selves. For organic beings are not rigid material systems ;
they are essentially forms of the dynamic equilibrium of
238 THE ANALYSIS OF SENSATIONS
currents of "matter" and "energy." Now it is the forms
of the deviation of these currents from the state of dynamic
equilibrium that always repeat themselves in the same way,
according to the way in which they have once been intro-
duced. Such variations in the forms of dynamic equilibrium
have still been but little studied by inorganic physics. As
a very rough example we may take changes in the flow of
liquids, produced by some chance circumstance, and then
maintained. If we screw up a tap so tightly that only a
thin, quiet trickle of water comes but, a chance jolt is
enough to disturb the unstable equilibrium of the trickle,
and to cause the water to run out in drops with a persistent
rhythm. Suppose that a chain, lying coiled up in a tub,
is allowed to run over a roller acting as a sort of lever,
and to fall into another tub at a lower level. If the chain
is very long and the difference of level very great, the
velocity may. become considerable, and then the chain,
as is well known, has the property, whenever it is made to
take a loop, of keeping this loop suspended in the air for
some time, and continuing its flow in this shape. All these
examples are very inadequate analogies to the plasticity
which organisms possess for the repetition of processes
and series of processes.
The foregoing considerations are intended to shew that
a comprehension of memory on physical lines is not un-
attainable, although we are still very far removed from it.
There can be no doubt that a considerable enlargement
of the point of view of physical science by means of the
study of organic beings is required, before physics is
capable of such a task. The great richness of memory is
founded, no doubt, upon the reciprocal interaction and
THE ANALYSIS OF SENSATIONS 239
connexion of the organs. Still, we probably must ascribe
a rudimentary memory even to elementary organisms ; and
if so, the idea inevitably suggests itself that, every chemical
process in the organ leaves traces behind which are favour-
able to the reappearance of the same process. 1
It is well known that a very prominent position is given,
in psychology, to the laws of association. These laws can
be reduced to a single law, which consists in saying that if
two contents of consciousness, A and B, have once appeared
simultaneously, one of them, when it arises, will evoke the
other. And in fact it is much easier to understand physical
life when we have recognized the constant recurrence of
this fundamental feature. The differences of mental pro-
cess, in simple memory of an experience, in serious occupa-
tion, and in the free exercise of fancy or day-dreaming, can
easily be understood by means of the concomitant cir-
cumstances. 2 It would, however, be a complete mistake to
try to reduce <z//(p. 201) psychical processes to associations
acquired during the life of the individual. In none of its
phases do we meet with the psyche as a tabula rasa. At
the very least we should have to assume innate associations
side by side with the acquired. The innate impulses, 3
1 Ostwald has made a bold attempt at a chemical theory of memory,
based on his theories about katalysis. See his Vorlesimgen fiber
Naturphilosophie, 1902, pp. 369 sqq.
2 Mach, Erkenntnis und Irrtuni, 1905, pp. 29 sqq.
3 The most striking of these, because they make their appearance at
the moment when the mental faculties and the power of observation are
fully developed, are the first manifestations of the sexual impulse. I
240 THE ANALYSIS OF SENSATIONS
which, to a psychology that is purely introspective and con-
fined to itself, must necessarily appear to be innate associa-
tions, are reduced by biology to innate organic connexions,
and, in particular, to nervous connexions. It is therefore
worth while to inquire whether all associations, including
those acquired by the individual, do not depend upon
innate connexions, of which some have been strengthened
by use. 1 But in any case we must also ask whether the
processes for the connexion of which in highly different-
iated organisms special paths have been evolved, are not
rather primary facts that already exist in lower organisms,
and whether it is not their repeated occurrence accompanied
by one another that has led to the formation of the paths
in question. 2 A rational psychology cannot, of course, be
content with temporary associations ; it will have to provide
for fixed paths of connexion also. Again, room must be
found for the possibility of spontaneous psychical pro-
cesses, not due to association, which excite the neighbor-
ing parts of the nervous system, and, when they are of great
have been told by a perfectly trustworthy man, a person with a strong
love of truth, that when he was a lad of sixteen, being quite innocent
and inexperienced at the time, he saw a lady in a low-necked dress,
and was startled to find that he was suddenly aware of a striking bodily
change in his person ; this change he took to be an illness, and con-
sulted a colleague about it. The whole complex of entirely new
sensations and feelings which were then suddenly revealed to him was
colored by a strong additional element of fear.
1 H. E. Ziegler, " Theoretisches zur Tierphysiologie und vergleich-
enden Neurophysiologie," Biologisches Zentralblatt ', Leipzig, 1900,
Vol. XX , No. i.
2 If we think of organic life as a state of dynamic equilibrium of
various chemical component-phases, in which, speaking generally, a
disturbance of one component causes a disturbance of the rest, we shall
then be justified in hoping to explain, not only memory, but association
too, on chemical lines. See p. 239 above, note i, and p. 99.
THE ANALYSIS OF SENSATIONS 241
violence, even spread over the whole nervous system. on
the one hand hallucinations, on the other reflex movements,
are examples from the sensational and motor spheres, to
which there are probably corresponding analogies in other
spheres.
Theories of the reciprocal action of the parts of the
central nervous system seem to be opposed to a view which
has been expounded by Loeb, 1 partly on the basis of his
own work, partly on that of Goltz and Ewald. This view
deserves to be noticed. According to it, the tropisms of
animals are not essentially different from those of plants,
the only advantage secured by the nerves in the case of
animals being the more rapid transference of stimulus.
The life of the nervous system is reduced to segmental
reflexes, the co-ordination of movements to reciprocal
excitation and transference of stimulus, and the instincts
to chains of reflexes. The snapping-reflex of the frog, for
instance, sets free the swallo wing-reflex. Organized centres
of great complication are not assumed, but the brain itself
is regarded as an arrangement of segments. At the bottom
of all these theories there lies, so far as I can judge, a
happily conceived and important effort to shake off the
trammels of unnecessarily complicated assumptions impreg-
nated with metaphysics. But I cannot agree with Loeb
when he treats Darwin's phylogenetic research on the
instincts as a fallacious and one-sided proceeding, which
ought to be dropped and replaced by physico-chemical
investigations. Research of that kind was, no doubt, not
1 Loeb, Vergleichende Physiologic des Gehirns, Leipzig, 1899.
9
242 THE ANALYSIS OF SENSATIONS
within Darwin's horizon. But it was precisely that fact
which secured for him the freedom of vision necessary to
his great and peculiar discoveries, which no physicist, qua
physicist, could have made. We are, indeed, everywhere
trying to obtain, where it is possible, some insight into the
physical constitution of things, some acquaintance with
their immediate, or causal, connexions. But it is far from
being the case that this is already possible everywhere.
And in cases where it is not possible, it would at all events
only be another and a very dangerous piece of one-sidedness,
to give up other fruitful points of view, which can always be
regarded as provisional. The steam-engine can, as Loeb
says, only be understood on physical lines. But this is only
true of a particular given steam-engine. When it is a
question of understanding the present forms of the steam-
engine, physical considerations are not sufficient. The
whole history of technical and social culture, and the
geological presuppositions involved, must be taken into
account. It is possible that, in the last resort, each one of
these factors is susceptible of a physical explanation, but it
has explained our difficulties long before that stage is
reached. 1
6.
If I can imagine that, while I am having sensations, I
myself or someone else could observe my brain with all the
necessary physical and chemical appliances, it would then
be possible to ascertain with what processes of the organism
sensations of a particular kind are connected. The question
so often asked, what is the lower limit of sensation in the
1 Loeb, Vergleichende Physiologic des Gehirns, p. 1 30.
THE ANALYSIS OF SENSATIONS 243
organic world, whether the lowest animals have sensations,
or whether plants have, could then be brought nearer to its
solution, at any rate so far as analogy goes. As long as
this problem has not been solved in even one single special
case, no decision of the question is possible. It is some-
times even asked whether inorganic "matter" has sensa-
tions. The question is natural enough, if we start from the
commonly current physical conception which represents
matter as the immediately and undoubtedly given reality
out of which everything, inorganic and organic, is con-
structed ; for sensation must either arise suddenly some-
where or other in this structure, or else have been present
in the foundation-stones from the beginning. From our
point of view the question is merely a perversion. Matter
is for us not what is primarily given. What is primarily
given is, rather, the elements, which, when standing to one
another in a certain known relation, are called sensations.
Every scientific problem that can have any meaning for a
human individual is concerned with the ascertainment of
the dependence of the elements on one another. What in
every-day life we call matter is a definite kind of connexion
between the elements. The question as to whether matter
has sensations would therefore run as follows : does sensa-
tion belong to a definite kind of connexion between the
elements, these elements themselves also being, when in a
certain relation, always sensations ? Put in this form ; no
one will want to ask the question. 1 Everything that can
have any interest for us must be reached in the course of
following out the general task of science. We ask whether
1 Cf. Mach, Popular- Wissenschajtliche Vorlesungen, 3rd ed., 1903,
p. 242.
244 THE ANALYSIS OF SENSATIONS
animals have sensations, when the assumption of sensations
helps us better to understand their behaviour as observed
by means of our own senses. The behaviour of a crystal is
already completely determined for our senses ; and thus to
ask whether a crystal has sensations, which would provide
us with no further explanation of its behaviour, is a
question without any practical or scientific meaning.
XII. THE SENSATION OF TIME. 1
i.
MUCH more difficult than the investigation of
space-sensation is that of time-sensation. Many
sensations make their appearance with, others without,
a clear sensation of space. But time-sensation accom-
panies every other sensation, and can be wholly
separated from none. We are referred, therefore, in our
investigations here, to the variations of time-sensation.
With this psychological difficulty is associated another,
consisting of the fact that the physiological processes with
which the sensation of time is connected are still less
known, lie deeper, and are more thoroughly concealed
than the processes corresponding to the other sensations.
Our analysis, therefore, must confine itself chiefly to the
psychological side, without approaching the question from
its physical aspect, as is possible, in part at least, in the
provinces of the other senses.
It is scarcely necessary to lay special emphasis on the
important part played in our psychical life by the temporal
1 The position which I here take differs only slightly from that of my
" Untersuchungen iiber den Zeitsinn des Ohres," Sitzber. d. Wiener
Akademie, Vol. LI. , 1865. Into the details of these earlier experiments,
begun in 1860, I shall not enter again here. Nor can I here discuss
the plentiful material which has resulted from the works of Meumann,
Munsterberg, Schumann, Nichols, Hermann, and others. Cp. Scripture,
The New Psychology, London, 1897, p. 170. For a supplementary dis-
cussion, see my Erkenntnis und Irrtttm, 1905, pp. 415 sqq.
245
246 THE ANALYSIS OF SENSATIONS
ordering of the elements. The temporal order is even
more important than the spatial. Reversal of the temporal
order is even more destructive of a process than is the
reversal of an object in space by turning it upside down ;
reverse the temporal order, and an experience becomes
something other than itself, something quite new. This is
why the words of a speech or a poem are reproduced only
in the order in which they were experienced and not in the
reverse order as well, in which they would generally have
a quite different meaning, or no meaning at all. If the
whole acoustic sequence is reversed by saying something
backwards, or by making a phonograph work backwards,
we do not even recognize any longer the words that are the
component parts of the speech. Definite memories are con-
nected only with the definite sequence of sounds in which
a word occurs, and it is only when the memories are
evoked in a definite order corresponding to the word-
sequence, that they combine together to produce a definite
meaning. 1 But a sequence of notes too, a simple melody
in which habit and association in any case play a very
small part, becomes unrecognizable if it is temporally
reversed. As regards even very elementary representa-
tions and sensations, their temporal sequence forms part
of the memory image of them.
If we conceive time as a sensation, it seems less strange
that, in a series passing in the order A B CD E, any member,
C for instance, should call up to the memory only the
members that follow it, and not those that precede. The
J Cp. R. Wallaschek, Psychologic nnd Pathologic der Vorstellung,
Leipzig, 1905, especially the chapter on " The Whole and its Parts/'
pp. I5sqq.
THE ANALYSIS OF SENSATIONS 247
memory-image of a building does not arise with the roof
turned downwards. But, for the rest, it does not seem to
be a matter of indifference whether the organ B is excited
after an organ A, or vice versa. There is probably a
physiological problem concealed here, which would re-
quire to be solved before we can fully understand the
fundamental psychological fact of the lapse of reproduced
series in one determined direction. 1 It is possible that
this fact is connected with the fact that an excitation
propagates itself along entirely different paths according
to the point at which it first enters into the organism, in
the way in which this was explained for physical cases by
the considerations on p. 92 and by Fig. \b. Even when
the medium is perfectly homogeneous, if two excitations
in it, starting from two distant points, spread uniformly,
they will more nearly coincide at that one of the two points
which was excited later. Thus, even in the simplest cases,
the order of stimulation cannot be a matter of indifference.
Let a note D follow a note C. The impression is quite
different from what it would be if C followed D. The
cause of this is chiefly the notes themselves, and their
reciprocal action. For if the pause between the two notes
is made sufficiently long, it is possible that we shall no
longer distinguish the two cases. Something analogous
can be observed with sequences of colors, and in general
1 Perhaps the nervous elements are not merely endowed with a per-
manent innate faculty of polar orientation, such as is made probable by
the backward direction of the wave in the intestines and the musculature
of snakes, and by galvanotropic phenomena, but perhaps they are also
capable of a temporarily acquired polarity, as manifested in the
inclusion of the time-series in memory, in practice, etc. Cp. Loeb and
Maxwell, Zur Theorie des Galvanotropismus^ Pfliiger's Archiv, Vol.
LXIII. p. 121 ; Loeb, Vergleichende. Gehirnphysiologie, pp. 108 sqq.
248 THE ANALYSIS OF SENSATIONS
with sensations of any kind. But if a note A is followed
by a color or a smell B, we always know that B has followed
A, and our estimate of the pause between A and B is
practically not influenced at all by the quality of A and B.
There must therefore be a further process, which is un-
affected by variation in the quality of sensation, which is
quite independent of the quality of sensation, and by
means of which we estimate time. It is possible, indeed,
to make a sort of rhythm out of entirely heterogeneous
sensations, such as sounds, colors and impressions of
touch.
That a definite, specific time-sensation exists, appears to
me beyond all doubt. The rhythmical identity of the two
r
adjoined measures, in which the sequence of the notes is
quite different, is immediately recognized. We have not
to do here with a matter of the understanding or of reflexion,
but with one of sensation. In the same manner that
bodies of different colors may possess the same spatial
form, so here we have two tonal entities which, acoustically,
are differently colored, but possess the same temporal
form. As in the one case we pick out by an immediate
act of feeling the identical components of the space-sensa-
tion, so here we immediately detect the identical components
of the time-sensation, or the sameness of the rhythm.
It is of course only for small times that I hold that there
THE ANALYSIS OF SENSATIONS 249
is an immediate sensation of time. We judge and estimate
longer times by remembering the processes that took place
in them, that is to say, by splitting them up into the
smaller parts of which we had an immediate sensation.
on hearing a number of strokes of a bell, which are
exactly alike acoustically, I discriminate between the first,
second, third, and so on. Is it perhaps the accompanying
thoughts, or other accidental sensations, with which the
strokes of the bell happen to be associated, that produce
these distinguishing marks? I do not believe that any
one will seriously uphold this view How uncertain and
unreliable, if this view were true, would our measurement
of time be ! What would become of it if that accidental
background of thought and sensation should suddenly
vanish from memory?
While I am reflecting upon something, the clock strikes,
but I give no heed to it. After it has finished striking, it
may be of importance to me to count the strokes. And
as a fact, there arise in my memory distinctly one, two,
three, four strokes. 1 give here my whole attention to this
recollection, and by this means the subject on which I was
reflecting during the striking of the clock, for the moment
completely vanishes from me. The supposed background
against which I could note the strokes of the bell, is now
wanting to me. By what mark, then, do I distinguish the
second stroke from the first ? Why do I not regard all
the strokes, which in other respects are identical, as one ?
Because each is connected for me with a special time-
250 THE ANALYSIS OF SENSATIONS
sensation which starts up into consciousness along with it.
In like manner, I distinguish a memory-image from a
creation of fancy by a specific time-sensation which is not
that of the present moment.
Since, so long as we are conscious, time-sensation is
always present, it is probable that it is connected with the
organic consumption necessarily associated with conscious-
ness, that we feel the work of attention as time. During
any severe effort of attention time is long to us, during
easy employment short. When we are in a dull. state,
hardly noticing our surroundings, the hours pass rapidly
away. When our attention is completely exhausted, we
sleep. In dreamless sleep, the sensation of time is lacking.
When profound sleep intervenes, yesterday is connected
with to-day only by an intellectual bond, apart from the
feeling common to both that remains the same.
I have already on a former occasion referred to the
apparent difference of the ways in which animals of
different sizes measure time. 1 But the measurement of
time seems to change with age as well. How short the days
seem to me now in comparison with the days of my youth !
And in my youth I used to watch an astronomical clock
that struck the seconds ; when I think of that clock now,
the second-stroke seems to be appreciably accelerated. I
cannot shake off the impression that my physiological time-
unit has become larger.
The fatiguing of the organ of consciousness goes on con-
1 Zeitsinn des OAres, p. 17.
THE ANALYSIS OF SENSATIONS 251
tinually in waking hours, and the labor of attention increases
just as continuously. The sensations connected with
greater expenditure of attention appear to us to happen
later.
Normal as well as abnormal psychical events appear to
accord with this conception. Since the attention cannot be
fixed upon two different sense-organs at once, the sensa-
tions of two organs can never occur together and yet be
accompanied by an absolutely identical effort of attention.
Hence, the one appears later than the other. Something
analogous to the so-called personal equation of astronomers,
having its ground in analogous facts, is also frequently
observed in the same sense-province. It is a well-known
fact that an optical impression which arises physically later
may yet, under certain circumstances, appear to occur
earlier. It sometimes happens, for example, that a surgeon,
in bleeding, first sees the blood spirt out and afterwards his
lancet enter. 1 Dvorak has shewn, 2 in a series of experi-
ments which he carried out at my desire, years ago, that
this relation may be produced at will, the object on which
the attention is centred appearing (even when it is really
from 1/8 to 1/6 of a second later) earlier- than that indirectly
seen. It is quite possible that the familiar experience of
the surgeon may find its explanation in this fact. The time
which the attention requires to turn from one place at which
it is occupied, to another, is shewn in the following experi-
1 Compare Fechner, Psychophysik^ Leipzig, 1860, Vol. II.,
P- 433-
2 Dvorak, u Ueber Analoga der persb'nlichen Differenz zwischen
beiden Augen und den Netzhautstellen desselben Auges," Sitzbcr. d.
konigl, bohm. Gesellschaft der Wissenschaften (Math-naturw. Classe),
March 8, 1872,
252
THE ANALYSIS OF SENSATIONS
green
red
ment instituted by me. 1 Two bright red squares measuring
two centimeters across and situated on a black background
eight centimeters apart, are illuminated in a perfectly dark
room by an electric spark concealed from the eye. The
square directly seen appears red, but that indirectly seen
appears green, ^and often quite
intensely so. The retarded
attention finds the indirectly
seen square when it is already
in the stage of Purkinje's positive
after-image. A Geissler's tube
with two bright red spots at a
short distance from one another,
exhibits, on the passage of a single discharge, the same
phenomenon. 2
The reader must be referred for details to Dvorak's paper.
Of particular interest are his experiments on the stereoscopic
(binocular) combination of non-simultaneous impressions. 3
More recently Sandford 4 and Miinsterberg 5 have carried
out experiments of this kind.
indir. seen
dir. seen
Fig. 34-
I have repeatedly observed an interesting phenomenon
which should be cited here. I have been sitting in my
1 Communicated by Dvorak, loc. cit.
-G. Heymans could not succeed at first in this latter experiment,
but has subsequently convinced himself of the correctness of my
statement.
3 Op. cit. , p. 2.
* Sandford, American journal of Psychology, 1894, Vol. VI., p. 576.
5 Miinsterberg, Psychological Reviezv, 1894, Vol. I., p. 56.
THE ANALYSIS OF SENSATIONS 253
room, absorbed in work, while in an adjacent room experi-
ments in explosions were being carried on. It regularly
occurred that I shrank back startled, before I heard the report.
Since the attention is especially inert in dreams, naturally
the most peculiar anachronisms occur in this state, as every
one has doubtless observed. For instance, we dream of a
man who rushes at us and shoots, awake suddenly, and per-
ceive the object which, by its fall, has produced the entire
dream. Now there is nothing absurd in assuming that the
acoustic stimulus enters simultaneously different nerve-
tracks and is met there by the attention in some inverted
order, just as, in the case above mentioned, I perceived
first the general excitation and afterwards the report of the
explosion. But in many cases it is undoubtedly a sufficient
explanation to assume the interweaving of a sensation with
the framework of a dream already present.
6.
If organic consumption, or, for that matter, the accumula-
tion of fatigue-material were immediately felt, we might
logically expect a reversal of time in dreams. The diffi-
culty disappears if consumption and restitution are regarded
as heterodromous processes in Pauli's sense (see p. 68 above).
The eccentricities of dreams may all be accounted for by
the fact that many sensations and representations do not
enter consciousness at all, while others enter with too much
difficulty and too late. Inertia of association is a funda-
mental feature of dreams. The intellect often sleeps only
in part. We converse very sensibly, in dreams, with persons
long dead, but with no recollection of their death. I
254 THE ANALYSIS OF SENSATIONS
speak to a friend of a third person, and this friend is him-
self the third person of whom I was speaking. We reflect,
in the dream-state, concerning dreams, and recognize them
as such by their eccentricities, which then at once cease to
disturb us. I once dreamed very vividly of a mill. The
water flowed downwards, in a sloping channel, away from the
mill, and close by, in just such another channel, upwards
to the mill. I was not at all disturbed by the contradic-
tion. At a time when much engrossed with the subject
of space-sensation, I dreamed of a walk in the woods.
Suddenly I noticed the defective perspective displacement
of the trees, and by this recognized that I was dreaming.
The missing displacements, however, were immediately
supplied. Again, while dreaming, I saw in my laboratory
a beaker filled with water, in which a candle was serenely
burning. " Where does it get its oxygen from ? " I thought.
11 It is absorbed in the water," was the answer. " Where
do the gases produced in the combustion go to?" The
bubbles from the flame mounted upwards in the water,
and I was satisfied. W. Robert l has made the excellent
observation that it is principally perceptions and thoughts,
which owing to some interruption we have been unable to
carry to a conclusion during the day, of which the thread
is taken up in dreams. And as a matter of fact we fre-
quently draw the elements of our dreams from the events
of the preceding day. Thus I used to be able to refer,
with almost complete certainty, the dream about the light
in the water to a certain experiment in my lectures with an
electric carbon-light under water, 2 and the dream about
1 W. Robert, Ueber den Traum, Hamburg, 1886.
* Prinzipien der Warmelehre> 2nd ed., 1900, p. 444.
THE ANALYSIS OF SENSATIONS 255
the mill to my experiments with the apparatus described on
p. 143 (Fig. 19) above. Visual hallucinations play the prin-
cipal part in my dreams. I have acoustic dreams less often,
though I clearly hear conversations, the sound of bells, and
music in my dreams. 1 Every sense, even the sense of taste,
can come into play in dreams, though some more rarely
than others. Since reflex excitability is greatly heightened
in the dream-state, and the conscience on the other hand
very much weakened owing to the inertia of association,
one is capable of almost any crime in dreams, and at the
stage of waking may go through the acutest torments.
Anyone who allows such experiences to affect him, must
entertain grave doubts as to the Tightness of our method of
exercising justice, which consists in making good one misery
by a second, the second being added to the first by means
of a process that is revolting because deliberate, cruel, and
solemn.
I should not like to let this opportunity slip of recommend-
ing to the reader the excellent book of M. de Manaceine. 2
What was said above as to the inadequacy of temporary
associations as an explanation of psychical life (see pp. 201,
239, 240) holds for the dream-state also. We have to add
that the faintest traces of something which has long been
forgotten for the waking consciousness, the slightest disturb-
ances of health and disposition which have to fall into the
background during the bustle of the day, can make them-
selves felt in dreams. In his Philosophic der Mystik (1885,
p. 123) Du Prel poetically compares this process with the
1 Wallaschek, "Das musikalische Gedachtnis," Vierteljahrsschrift
fiir Musikivissenschaft, 1882, p. 204.
2 M. de Manac6ine, Sleep, its Physiology ', etc., London, 1897.
256 THE ANALYSIS OF SENSATIONS
way in which the faintly glimmering starry firmament be-
comes visible when the sun has set. This book contains
many passages of remarkable and profound insight. The
man of science, in particular, whose critical sense is directed
towards the nearest practicable object of research, reads it
with pleasure and profit, without allowing himself to be led
astray by the author's inclination towards the fantastic, the
miraculous and the extraordinary.
If time-sensation is connected with the growth of organic
consumption or with the equally continuous growth of the
effort following upon attention, then we can understand why
physiological time is not re-
versible, any more than physi-
I f 1 i cal time, but moves only in one
direction. As long as we are
in the waking state, consumption and the labor of attention
can only increase, not diminish. The two accompanying
bars of music, which present a symmetry to the eye and
to the understanding, shew nothing of the sort as regards
the sensation of time. In the province of rhythm, and of
time in general, there is no symmetry.
8.
It is perhaps an obvious and natural, though still an im-
perfect conception, to regard the " organ of consciousness "
as capable, in a small degree, of all the specific energies, of
which each sense-organ is able only to display a few. Hence
THE ANALYSIS OF SENSATIONS 257
the shadowy and evanescent character of representation as
compared with sensation, through which it must be con-
stantly nourished and refreshed. Hence also the capacity
of the organ of consciousness to serve as a bridge of
connexion between all sensations and memories. With
every specific energy of the organ of consciousness, we
should then have to conceive still another particular energy,
the sensation of time, associated, so that none of the former
could be excited without the latter. Should this new energy
appear physiologically superfluous and only invented ad hoc,
we might at once assign to it an important physiological
function. What if this energy kept up the flow of blood
that nourishes the brain-parts in their work, guided this
current to its destination, and regulated it ? Our con-
ception of attention and of time-sensation would then
receive a very material basis. The fact that there is
only one cohering time, too, would become intelligible,
since the partial attention given to one sense is
always drawn from the total attention, and is determined
by it.
Such a theory is strongly suggested by Mosso's work on
plethysmography and by his observations on the circulation
of the blood in the brain. 1 William James gives a cautious
assent to this conjecture. 2 James indicates that it
would be desirable to put it into a more definite and
detailed form, but I have unfortunately not been able to
do this.
1 Mosso, Kreislauf dcs Bhites im Gehirn, Leipzig, 1881. Cf. also
Kornfeld, Ueber die Beziehiing von Atmung und Kreislauf zur geistigen
Arbeit, Briinn, 1896.
2 W. James, Psychology, Vol. I., p. 635.
R
258 THE ANALYSIS OF SENSATIONS
In listening to a number of similar strokes from a bell,
we can distinguish each from the others in memory and
also count them in memory, provided they are few in
number. If the number is large, however, we distinguish
the last ones from one another, but not the first. In this
case, if we would not make a mistake, we must count them
immediately upon their being sounded, that is, we must
voluntarily connect each stroke with an ordinal symbol.
The phenomenon is perfectly analogous to that which we
observe in the province of the space-sense, and is to be
explained on the same principle. In walking forwards, we
have a distinct sensation that we are moving away from a
starting-point, but the physiological measure of this removal
is not proportional to the geometrical. In the same
manner, elapsed physiological time is subject to perspectival
contraction, its single elements becoming less and less
distinguishable. 1
10.
If a special time-sensation exists, it goes without saying
that the identity of two rhythms will be immediately re-
cognized. But we must not leave the fact unnoticed that
two rhythms which are the same physically may appear
very different physiologically, just as the same space-figure
by change of position may give rise to different physio-
logical space-forms. The rhythm represented by the
following notes, for example, appears quite different accord-
1 Cp. p. 134.
THE ANALYSIS OF SENSATIONS 259
ing as we regard the short thick, or the long thin vertical
lines, or the dotted lines, as marking the bars. Evidently
this is connected with the fact that the attention (guided by
the accent) sets in at i, 2, or 3, that is, that the sensations
nn
of time corresponding to the successive beats are compared
with different initial sensations.
When all the times of a rhythm are prolonged or
shortened, a similar rhythm arises, which, however, can only
be felt as similar when the prolongation or shortening does
not exceed the limit imposed by the immediate sensation
of time.
The rhythm represented in the following diagram appears
physiologically similar to the preceding, but only when
similarly-marked bars are taken in the two that is, when
the attention sets in at homologous points of time. Two
physical time-constructions may be termed similar when all
the parts of the one stand in the same relation to one
another as do the homologous parts of the other. But
physiological similarity makes its appearance only when the
above condition is likewise fulfilled. Furthermore, so far as
I am able to judge, we recognize the identity of the time-
ratios of two rhythms only when the same are capable of _.
being represented by very small whole numbers. Thus we
260 THE ANALYSIS OF SENSATIONS
really notice immediately, only the identity or non-identity
of two times, and, in the latter case, we recognize the ratio
of the two only by the fact that one part is exactly contained
in the other. Herewith we have an explanation of the fact
that, in marking time, the time is always divided into
absolutely equal parts. 1
The conjecture thus forces itself upon us, that the sensa-
tion of time is closely connected with periodically or
rhythmically repeated processes. But it is scarcely capable
of being proved, though the attempt has been made in some
quarters, that the measurement of time in general is based
on breathing or on the pulse. These questions, however,
are by no means simple. Many processes, of course, take
place rhythmically in the bodies of animals, without it
being possible for us to attribute to them any particular
sense for time, rhythm or beat. When a pair of horses is
driven past my house, I can hear for a long time the
coincidence and alternation of the hoof-beats of the two
horses fading away into the distance in regular periods.
Thus each horse keeps to its own time without troubling
about that of the other horse, and without adapting itself to
the other. Two men harnessed together would find this
almost intolerable. Wallaschek mentions the deficiency
of the sense of time in horses, and also the difficulty of
keeping up the appearance of it in circus performances. It
can scarcely be upon the coarser bodily processes that the
feeling for time is immediately based. Probably it must be
referred rather to a superior psychical sensibility, in virtue
of which a trifling psychical circumstance determines the
1 The similarity of space-figures would be felt, according to this theory,
much more immediately than the similarity of rhythms.
THE ANALYSIS OF SENSATIONS 261
attention to notice an otherwise indifferent process. But
when processes that keep time are carefully observed, and
such observation always involves a certain amount of co-
operation and imitation, the psychical functions, and
finally the coarser bodily functions themselves also, then
become adapted to the time. 1
Dr. R. Wlassak has communicated to me in conversation
a remark which I will reproduce in his own words :
"When the sensations are connected with a vivid
emotional coloring, time-values are always markedly dimin-
ished ; this fact accords with the hypothesis that the sensa-
tion of time depends on organic consumption. Xhe rule
holds both for stretches of time that are filled with strongly
pleasurable sensations and for those filled with unpleasant
sensations. on the other hand, the sensations that oscillate
round the indifference-values of emotional coloring are con-
nected with relatively indistinct sensations of time. These
facts indicate that the nervous processes belonging to the
sensations of time and to the emotions respectively offer
certain analogies.
In point of fact, all attempts to frame a ^physiological
theory of the emotions bring the emotions into relation with
consumption; as is done, for instance, in Meynert's or in
Avenarius' theory of the emotions."
1 Wallaschek, Anfilnge der Tonkunst, Leipzig, 1903, pp. 270, 271.
This book, a profusely illustrated German edition of an English book
by the same author (Primitive Music, London, 1903), contains many
very valuable observations on the questions discussed in this and the
following chapters.
XIII. SENSATIONS OF TONE. 1
i.
AS regards tone-sensations, also, we are restricted mainly
to psychological analysis. As before, the beginning
of an investigation is all we can offer.
Among the sensations of tone possessing greatest im-
portance for us are those excited by the human voice, as
utterances of pleasure and pain, of ｅxpressions of the will,
and of the communication of thoughts by speech, etc. Nor
can there be any doubt that the voice and the organ of
hearing bear a close relation to each other. The simplest
and distinctest form in which sensations of tone reveal their
remarkable characteristics is music. Will, emotion, the
ｅxpression of sound, and the sensation of sound, have
certainly a strong physiological connexion. There is a
good deal of truth in the remark of Schopenhauer 2 that
music represents the will, and in fact generally in the
"* Apart from details, I have held the position here taken up since 1865.
Stumpf, whom I must here thank for the repeated consideration of my
work, has many points of detail (Tonpsychologie, Leipzig, 1883, Vol. I.)
that appeal to me. The view expressed on page 1 19 of his work, how-
ever, seemed incompatible with the principle of parallelism, my
fundamental axiom of research ; though the remark which he directs
against Lipps (Beitrdge zur Akuitik, Vol. I., p. 47, footnote), repre-
sents an approximation to my point of view. Compare my note, " Zur
Analyse der Tonempfindungen," Sitzungsberichte der Wiener Akademie^
Vol. XCIL, II. Abth., p. 1282 (1895).
8 Schopenhauer, Die Welt als Wille tind Vorstelhtng.
262
THE ANALYSIS OF SENSATIONS 263
designation of music as a language of emotion ; although
this is scarcely the whole truth.
2.
Following the precedent of Darwin, H. Berg has, to put
it shortly, attempted to derive music from the amatory cries
of monkeys. 1 We should be blind not to recognize the
service rendered and enlightenment conveyed by the work
of Darwin and Berg. Even at the present day, music has
power to touch sexual chords, and is, as a fact, widely made
use of in courtship. But as to the question wherein con-
sists the agreeable quality of music, Berg makes no satis-
factory answer. And seeing that in musical theory he
adopts Helmholtz's position of the avoidance of beats and
assumes that the males who howled least disagreeably
received the preference, we may be justified in wondering
why the most intelligent of these animals were not prompted
to maintain silence altogether.
The importance of tracing the connexion of a given
biological phenomenon with the preservation of the species,
and of indicating its phylogenetic origin, cannot be under-
rated. But we must not imagine that in having accomplished
this we have solved all the problems connected with the
phenomenon. Surely no one will think of explaining the
element of pleasure in the specific sexual sensation by show-
ing its connexion with the preservation of the species. We
should be more likely to acknowledge that the species is
preserved because the sexual sensation is pleasurable.
Although music may actually remind our organism of the
1 H. Berg, Die Lust an der Musik, Berlin, 1879.
264 THE ANALYSIS OF SENSATIONS
courtship of distant progenitors, it must, if it was ever used
for wooing, have contained at the start some positive
agreeable quality, which, to be sure, may be reinforced at
the present time by that memory. To take an analogous
case from individual life, the smell of an oil-lamp as it goes
out almost always agreeably reminds me of the magic lantern
which excited my wonder as a child. Yet in itself the
smell of the lamp is none the less disgusting for this reason.
Nor does the man who is reminded, by the scent of roses,
of a pleasant experience, believe, on this account, that the
scent was not previously agreeable. It has only gained by
the association. 1 And if the view in question cannot
sufficiently explain the agreeable quality of music per se, it
assuredly can contribute still less to the solution of special
questions, as, for instance, why, in a given case, a fourth
is preferred to a fifth.
A rather one sided view of the sensations of tone would
be obtained if we were to consider only the province of
speech and music. Sensations of tone are not only a
means of communicating ideas, of expressing pleasure and
pain, of discriminating between the voices of men, women,
and children ; they are not mere signs of the exertion or
passion experienced by the person speaking or calling;
they also constitute the means by which we distinguish
between large and small bodies when sounding, between
the tread of large and small animals. The highest tones,
the very ones which the vocal organs of man cannot pro-
1 Fechner, notably, has emphasized the significance of association
for aesthetics.
THE ANALYSIS OF SENSATIONS 265
duce, presumably are of extreme importance for the deter-
mination of the direction from which sounds proceed. 1 In
fact, it is more than likely that these latter functions of
sensations of tone antedated, in the animal world, by a long
period, those which merely perform a part in the social life
of animals. By inclining a piece of cardboard in front of
the ear, anyone can convince himself that it is only those
noises which contain very high tones, such as the rustling
and hissing of a gas flame, of a steam kettle, or of a water-
fall, that are modified by reflexion according to the position
of the cardboard, and that deep tones remain entirely
uninfluenced. This shews that it is only in virtue of their
effect on high tones that the two ear-conchs can be
used as indicators of direction. 2
There is no one but will cheerfully acknowledge the
decided advance effected by Helmholtz in the analysis of
auditory sensations, 3 following on the important works of
his predecessors, Sauveur, Rameau, R. Smith, Young, Ohm,
1 Mach, " Bemerkungen liber die Function der Ohrmuschel "
(Troltsch's Archiv Jur Ohrenheilkunde, New Series, Vol. III., p 72).
Compare also Mach and Fischer, "Die Reflexion und Brechurig
des Schalles, Fogg. Ann., Vol. CXLIX., p. 221; A. Steinhauser,
Theorie des binaurealen Horens, Vienna, 1877.
2 I once had occasion to observe that tame marmots that were quite
insensible to deep and loud noises, were suddenly frightened, and
always rushed into hiding, whenever anyone produced a high-pitched
noise by rubbing straw or crackling paper. Children a few months old
are also very sensitive to such noises.
3 Helmholtz, Die Lehre von den l^onempfindungen, 1st ed. , Bruns-
wick, 1863.
266 THE ANALYSIS OF SENSATIONS
and others. 1 Following his principles, we recognize in
noises combinations of musical tones, of which the number,
pitch, and intensity vary with the time. In compound
musical sounds, or clangs, we generally hear, along with the
fundamental n, the over-tones or partial tones" 2n, $n, 471,
etc., each of which corresponds to simple pendular vibra-
tions. If two such musical sounds, to the fundamentals
of which the rates of vibration n and m correspond, be
melodically or harmonically combined, there may result,
if certain relations of n and m are satisfied, 2 a partial coin-
cidence of the harmonics, whereby in the first case the
relationship of the two sounds is rendered perceptible, and
in the second a diminution of beats is effected. All this
cannot be disputed, although it may not be considered
exhaustive.
We may also give our assent to Helmholtz's physiological
theory of audition. The facts observed on the simultaneous
sounding of simple notes make it highly probable that there
exists, corresponding to the series of vibration-rates, a series
of terminal nervous organs, so that for all the different rates
of vibration there are different end-organs, each of which
responds to only a few, closely adjacent rates of vibration.
on the other hand, Helmholtz's physical theories as to the
function of the labyrinth have proved untenable. I shall
return to this point.
5-
If we assume with Helmholtz that all noises admit of
1 Cp. " Zur Geschichte der Akustik " in my Popiilar-ivissenschoftliche
Vorlesungen.
3 The /th harmonic of n coincides with the ^th of m when pn - qm t
that is m = (plq) n, where/ and q are whole numbers.
THE ANALYSIS OF SENSATIONS 267
being resolved into sensations of tone varying in duration,
it seems superfluous to seek further for a special auditive
organ for noises, and Helmholtz himself soon gave up so
inconsequent a procedure. A long time ago (in the winter
of 1872-73) I took up the question of the relation of noises
(especially that of sharp reports) to musical tones, and
found that every degree of transition between the two may
be demonstrated. A tone of one hundred and twenty-eight
full vibrations, heard through a small radial slit in a slowly
revolving disc, contracts, when its duration is reduced to
from two to three vibrations, to a short, sharp concussion
(or weak report) of very indistinct pitch, while with from
four to five vibrations, the pitch is still perfectly distinct.
on the other hand, with sufficient attention, a pitch, though
not a very definite one, may be detected in a report even
when the latter is produced by an aperiodic motion of the
air (the wave of an electric spark, exploding soap-bubbles
filled with 2ff+ O). We may easily convince ourselves,
furthermore, that in a piano from which the damper has
been lifted, large exploding bubbles mainly excite to sym-
pathetic vibration the lower strings, while small ones
principally affect the higher strings. This fact, it seems
clear to me, demonstrates that the same organ may be the
mediator of both tone and noise sensation. We must
imagine that weak aperiodic movements of the air having
short durations excite all, though preferably the small and
more mobile end-organs, whilst more powerful and more
lasting movements of the air excite the larger and more
inert end-organs as well, which from being less damped
perform vibrations of greater amplitude and are thus
noticed ; and furthermore that even in the case of com-
268 THE ANALYSIS OF SENSATIONS
paratively weak periodic movements of the air, the stimulus
appears, by an accumulation of effects, in some definite
member of the series of end-organs. 1 The sensation excited
by a report of low or high pitch is qualitatively the same
as that produced by striking at once a large number of
adjacent piano-keys either high or low in the scale, only
more intense and of shorter duration. Moreover, in the
single excitation produced by a report, the beats connected
with periodic intermittent excitations are eliminated.
6.
The work of Helmholtz excited general admiration on
its first appearance ; but of late years it has been subjected
to various critical attacks, and it almost seems to be as
much underestimated now as it was originally overesti-
mated. Physicists, physiologists and psychologists have
had nearly forty years in which to test the three several
sides of the theory, and it would have been a marvel if
they had not found out its weak spots. Without making
any pretence to completeness, we will now consider the
principal critical objections to it, taking first together the
objections which have been urged from the physical and
physiological side, and, secondly, those of the psycholo-
gists.
1 I gave an account of part of my experiments, which were a con-
tinuation of Dvorak's researches on the after-images due to variations
of stimulus (1870), in the August number of Lotos, 1873. I have never
before mentioned the experiments relative to the excitement of piano-
tones by explosions. It will not be amiss, perhaps, if I do so here.
Ffaundler, S. Exner, Auerbach, Briicke, W. Kohlrausch, Abraham
and Brtihl, and others, subsequently treated the same questions in
detail, and from various points of view.
THE ANALYSIS OF SENSATIONS 269
Helmholtz assumed, for psychological and physical
reasons, that the inner ear consists of a system of resonators,
which singles out the members of Fourier's series, corre-
sponding to the form of vibration presented, and hears
them as partial tones. on this view, the relation between
the phases of the partial vibrations can exert no influence
on sensation. As against this view, Konig, 1 an eminent
specialist in acoustics, tried to prove that mere displacement
of the phases of the partial pendular vibrations causes a
change in the sensational impression or "sound-color."
L. Hermann, 2 however, succeeded in shewing that when
the direction of movement of a phonograph is reversed,
no change of sound-color results. According to Hermann,
the individual sinuous bands of Konig's wave-siren do not
produce any simple tones, and Konig's conclusions must
therefore be based on a mistaken presupposition. 3 This
difficulty may therefore be taken as removed.
The phenomena connected with the combination of
tones are not so easily explicable on Helmholtz' point of
view. Young supposed that beats of sufficient rapidity
1 R. Konig, Quelques experiences d'acoustique, Paris, 1882.
2 L. Hermann, "Zur Lehre von der Klangwahrnehmung," Pfliiger's
Archiv, Vol. LVI., 1894, p. 467.
3 As long ago as 1867, I instituted experiments with a special kind of
siren, very similar to one of Konig's apparatus. The casing of a
cylinder was fitted with rings in which were cut wave-shaped slips in
similar pairs capable of mutual displacement towards one another, so
that the intensity and the phase of the partial tone under investigation
could be varied at will. But it appeared on experiment that the wave-
shaped slits did not yield any simple tones when air was blown against
them through a slit parallel to the ordinate of the waves. As my
apparatus was still pretty imperfect, and did not fulfil its purpose,
which was to compound a sound from partial tones of given intensity
and phase, I have not published any account of these experiments.
270 THE ANALYSIS OF SENSATIONS
could themselves be heard as tones that is to say, that
they become compound tones. But since it is impossible
to excite any resonator by means of beats, to the tempo of
which it is tuned, but only by means of tones, it would be
impossible, on the resonance theory, to hear any compound
tones. Helmholtz therefore postulated at the outset that
compound tones must either be explained objectively by
means of powerful tones in virtue of the deviation of similar
vibrations from linearity, or subjectively by means of
asymmetrical or non-linear conditions of vibration of the
resonating parts of the inner ear. Now Konig 1 failed to
prove the existence of objective compound tones, but
discovered on the other hand that, even between tones
widely removed from one another, there are beats which
can invariably be heard as particular tones when the
sequence is sufficiently rapid. Hermann 2 detected com-
pound tones with co-operating tones of such feebleness,
that the compound tones seem entirely inexplicable
on Helmholtz' theory, either objectively or subjectively.
Hermann accordingly holds the view, associating himself
1 Konig, op. cit. He got his tones by a very powerful tuning-fork,
and I could not help conjecturing when his book appeared that, in
connexion with his observations of the beats, the overtones came into
play in various ways. Since then Stumpf has actually demonstrated
the co-operation of such overtones ( Wiedemann's Annalen, New Series,
Vol. LVII. , p. 660). Thus the theory of Helmholtz is safe on this side.
Still, the objection remains that the objective compound tones do not
exist (Konig, Hermann), and that subjective compound tones occur
in circumstances which are not compatible with Helmholtz' theory
(Hermann). Cp. also M. Meyer, " Zur theorie der Differenztone und
der Gehorsempfindungen Ueberhaupt," Zeitschrijt fur Psychologic.
Vol. XVI., p. I.
2 Hermann, " Zur Theorie der Kombinationstone," Pfliiger's Archiv,
Vol. XLIX., 1891, p. 499.
THE ANALYSIS OF SENSATIONS 271
on this point with Konig, that the ear re-acts, not only
to wave-shaped vibrations, but also, with a sensation deter-
mined by the duration of the period, to every kind of
periodicity.
The physical resonance-theory seems, at any rate, in its
original form, not tenable; but Hermann 1 thinks that it
can be replaced by a physiological resonance-theory. I
will deal later with this view, as well as with Ewald's new
physical theory of audition.
We now turn to the principal objections brought against
Helmholtz from psychological points of view. The lack of
a positive factor in the explanation of consonance has been
very generally felt, the mere absence of beats not being
regarded as a sufficient and satisfactory characterization of
harmony. Thus A. v. Oettingen 2 feels the want of some
expressed positive element characteristic of each interval
(p. 30), and refuses to regard the value of an interval as
dependent upon the physical accident of the overtones
contained in the sounds. He believes that the positive
element in question is to be found in the accompanying
remembrance of the common fundamental tone (or tonic),
as the harmonics of which the composite notes or clangs of
the interval have often occurred, or in the accompanying
remembrance of the common overtone (or phonic) 3 belonging
to the two (pp. 40, 47). on the negative side of his criticisms
1 Hermann, Pfliiger's Arckiv, Vol. LVI. , p. 493.
z Harmoniesystem in dtialer Entwicklung (Dorpat, 1 866), p. 30.
3 [The lowest of the harmonics common to all I term the coincident
or phonic harmonic. Von Oettingen, Harmoniesystem in dualer
Entvoicklung, p. 32. Quoted by translator.]
272 THE ANALYSIS OF SENSATIONS
I am in complete agreement with Von Oettingen. But
" remembrance " does not quite fill the need of the theory,
for consonance and dissonance are not matters of represen-
tative activity, but of sensation. My opinion, therefore,
is that A. von Oettingen's conception is physiologically
inadequate. His enunciation of the principle of duality,
however (or of the principle of the tonic and phonic
relationship of composite notes), as also his conception of
dissonances as indeterminate composite musical sounds
admitting of more than one interpretation (p. 224), appear
to me to be valuable and positive services to science. 1
8.
Stumpf has in various writings criticized the doctrine of
Helmholtz with great penetration. 2 He questions, in the
first place, the two different definitions which Helmholtz
gives of consonance, the definition by disappearance of
beats, and the definition by coincidence of partial tones,
pointing out that the former is inapplicable to and not
characteristic of melodic sequence, and the latter inappli-
cable to and not characteristic of harmonic combination. A
1 A popular statement of the principle of duality, of which Euler
Tentamen novce theories tnusica, p. 103), D'Alembert (Elemens de
musique-, Lyons, 1766), and Hauptmann (Die Natur der Harmonik
und Metrik, Leipzig, 1853, translation by W. E. Heathcote, London,
Swan Sonnenschein & Co., 1888), had all a faint inkling, is to be found
in my Popular Scientific Lectures (Chicago, 1894), under the caption
" Symmetry" (originally published in 1872). Perfect symmetry, such
as is found in the province of sight, cannot be imagined in music, since
sensations of tone do not constitute a symmetrical system.
2 I am here chiefly following Stumpf's Beitrage zur Akustik und
Musi kwissensc haft, Heft I, Leipzig, 1898.
THE ANALYSIS OF SENSATIONS 273
pure triple compound note, intermitting according to the
nature of the beats, is not a dissonance. on the other
hand, examples can be given of the simultaneous sounding
of tones far removed from one another, which produce a
violent dissonance, although the beats become imper-
ceptible. If two notes of the tuning-fork are distributed
one to each ear, the beats do indeed sink very much into
the background, but without the distinction between con-
sonance and dissonance becoming any less. Subjectively
heard tones, too, such as ringing in the ears, can be experi-
enced as dissonances, of course without the beats being
heard. Tones, finally, that are merely represented, also
appear as consonant and dissonant, without the representa-
tion of beats playing any essential part in the process.
The coincidence of the partial tones ultimately disappears,
when no overtones are present, without necessarily causing
the disappearance of the distinction between dissonance
and consonance. I will pass over Stumpf s polemic against
the explanation of consonance by means of unconscious
counting, a view which will probably find few supporters. 1
Equally readily will it be admitted that agreeableness is
not a sufficiently characteristic property of consonance,
since it is a property which under certain circumstances can
just as well belong to dissonance.
Stumpf himself finds the characteristic mark of conson-
1 Such explanations were attempted by Leibniz and Euler, and have
been revived in more recent times by Oppel, later by Lipps (Psycho-
logische Studien, 1885), and finally, in a number of voluminous works,
by A. J. Polak ( Ueber Zeiteinheit in bezttg aiij Konsonanz, Harmonic
imd Tonalitat, Leipzig, 1900 ; Ueber Tonrhythmik und Stimmfiihrung,
Leipzig, 1902 ; Die Harmonisierung indischer, turkischer ^^nd japani-
scher Melodien, Leipzig, 1905).
S
274 THE ANALYSIS OF SENSATIONS
ance in the fact of two tones when sounded together
approximating, sometimes more and sometimes less, to the
impression of a single tone. He defines consonance by
means of " fusion," harking back, as it were, to views pre-
valent in antiquity, of which he gives an exhaustive history. 1
Helmholtz also is not unfamiliar with this theory ; he dis-
cusses it, but thinks that he has given the first correct
explanation of the fusion of notes.
Stumpfs statistical experiments shew that a fusion of
tones takes place in consonance. If two tones are sounded
simultaneously, unmusical persons mistake them for a
single tone with a frequency in proportion to the extent to
which they are consonant. Stumpf does not attempt to
conceal the necessity for some further explanation of fusion.
If it is similarity that causes tones to fuse, then this must
be a different kind of similarity from that on which the
sequence of tones in a series depends, since this latter
similarity decreases continuously with the distance of the
tones from one another. But since such a second relation
of similarity appears to him purely hypothetical, he prefers
to imagine a physiological explanation of a different kind.
He supposes that, when two tones, of which the rates of
vibration stand to one another in a comparatively simple
ratio, are heard simultaneously, the cerebral processes
which take place are connected by a closer relation of
specific synergy than when the ratio of the rates of vibration
is more complicated. 2 Tones that succeed one another
can fuse. Although polyphonous music is preceded his-
1 C. Stumpf, " Geschichte des Konsonanzbegiiffes," Abhandlwigen
der Munchener Akademie^ 1897.
2 C. Stumpf, Beitriige zur Akustik, Heft I, p. 50.
THE ANALYSIS OF SENSATIONS 275
torically by homophonous, yet Stumpf considers it probable
that even in the case of homophonous music the selection
of the scale was guided by experience of the simultaneous
hearing of tones. In all essential points it is impossible
not to agree with Stumpf s criticism.
I myself, as early as I863, 1 and also later, 2 had made
some critical remarks on the theory of Helmholtz, and
in 1866, in a small work 3 which appeared shortly before
that of Von Oettingen, I very definitely pointed out some
demands which a more perfect theory of the subject would
have to satisfy. I developed these remarks in more detail
in the first edition of this book (1886).
Let us start from the idea that a . series of definitely
graduated end-organs exists, the members of which, as the
rate of vibration increases, successively yield their maximum
response, and let us ascribe to each end-organ its particular
(specific) energy. Then there are as many specific energies
as there are end -organs, and as many rates of vibration
that we distinguish by the sense of hearing.
Further, we not only distinguish between tones, but we
also order them in a series. Of three tones of different
pitch, we recognize the middle one immediately as such.
1 Mach, "Zur Theorie des Gehororgans" (Sitztmgsberichte der
Wiener Akademie, 1863).
2 Cp. my " Bemerkungen zur Lehre vom raumlichen Sehen"
(Fichte's Zeitschrift ftir Philosophic, 1865), and see my Popular
Scientific Lectures.
3 Einleitung in die Helmholtzsche Musiktheorie, Graz, 1 866. See
the Preface and pp. 23 et seq., 46 and 48.
276 THE ANALYSIS OF SENSATIONS
We feel immediately which rates of vibration lie nearer
together and which are further apart. This is readily
enough explained for adjacent tones. For, if we represent
the vibration-amplitudes of a certain tone symbolically by
the ordinates of the curve abc. Fig. 35, and imagine this
curve gradually moved in the direction of the arrow, then,
since necessarily several organs always yield simultaneous
responses, neighboring tones will always have faint, common
excitations. But more distant tones also possess a certain
similarity ; and even between the highest and lowest tones
we can detect a resem-
blance. Consequently, in
accordance with the prin-
ciple of investigation by
which we are guided, we
are obliged to assume in
all tone - sensations com-
** mon component parts.
Consequently, there can-
not be as many specific energies as there are distinguishable
tones. For the understanding of the facts with which we
are here concerned, it suffices to assume only two energies,
which are excited in different proportions by different rates o*
vibration. Further complexity of the sensations of tone is
not excluded by these facts, but on the contrary is rendered
probable by phenomena to be discussed later.
Careful psychological analysis of the tonal series leads
immediately to this view. But even supposing we assume
a special energy for every end-organ, and reflect that these
energies are similar to one another, that is, must contain
common component parts, virtually we arrive at the same
THE ANALYSIS OF SENSATIONS 277
standpoint. Let us therefore assume, merely in order to
have a definite picture before us, that, in the transition
from the lowest to the highest rates of vibration, the
tonal sensation varies similarly to the color-sensation
in passing from pure red to pure yellow, say by the
gradual admixture of yellow. We can fully retain, on
this view, the idea that there is for every distinguishable
rate of vibration a special appropriate end-organ; but
in that case not absolutely different energies, but
always the same two energies, only in different propor-
tions, are disengaged by the different organs. 1
10.
How does it happen, now, that so many tones simul-
taneously sounded are distinguished, and are not fused into
a single sensation \ or that two tones of different pitch do
not blend to a mixed tone of intermediate pitch? The
fact that this does not happen, lends a still more definite
shape to the conception which we have to form. The case
is probably similar to that of a graduated series of mixed
reds and yellows situated at different points of space, which
are likewise distinguished and do not blend. And in fact,
the sensation which ensues when the attention passes from
one tone to another is similar to that which accompanies
1 The view that different end-organs respond to different rates of
vibration is too well supported by the production of beats by neighbor-
ing tones, and by other facts adduced by Helmholtz, and is too valuable
for the comprehension of the phenomena, to be again relinquished.
The view here presented utilizes the facts disclosed, notably by Hering,
in the analysis of color-sensations.
278 THE ANALYSIS OF SENSATIONS
the wandering of the fixation-point in the field of vision.
The tonal series occurs in something which is an analogue
of space, but is a space of one dimension limited in both
directions and exhibiting no symmetry like that, for instance,
of a straight line running from right to left in a direction
perpendicular to the median plane. It more resembles a
vertical right line, or one running from the front to the
rear in the median plane. But while colors are not con-
fined to certain points in space, but may move about,
which is the reason we so easily separate space-sensations
from color-sensations, the case is different with tone-
sensations. A particular tone-sensation can occur only
at a particular point of the said one-dimensional space, on
which the attention must in each case be fixed if the tone-
sensation in question is to be distinctly perceived. We
may now imagine that different tone-sensations have their
origin in different parts of the auditive substance, or that,
in addition to the two energies whose ratio determines the
timbre of high and deep tones, a third exists, which is
similar to a sensation of innervation, and which comes into
play in the fixation of tones. Or both conditions might
occur together. At present it may be regarded as neither
possible nor necessary to come to a conclusion in the
matter.
That the province of tone-sensation offers an analogy to
space, and to a space having no symmetry, is unconsciously
expressed in language. We speak of high tones and deep
tones, not of right tones and left tones, although our musical
instruments suggest the latter designation as a very natural
one.
THE ANALYSIS OF SENSATIONS 279
ii.
In one of my earliest publications 1 I supported the
view that the fixation of tones was connected with a
varying tension of the tensor tympanL I am now unable
to maintain this view in the light of subsequent observa-
tions and experiments which I have made. Nevertheless,
the space-analogy does not fall to the ground for this
reason ; only the appropriate physiological element remains
to be discovered. The supposition that the processes in
the larynx during singing have something to do with the
formation of the tonal series was likewise noticed by me
in my work of 1863, but I did not find it tenable. Singing
is connected with hearing in too extrinsic and accidental
a manner. I can hear and imagine tones far beyond the
1 Zur Theorie des Gehororgans, 1863. By means of experiments
carried out by me in co-operation with Kessel (" Ueber die Akkommo-
dation des Ohres," Sitzungsberichte der Wiener Akademie, Vol. LXVI.,
part 3, October 1872), I obtained a proof of the variable disposition
and capacity for resonance of the anterior auditory apparatus in the
case of different tones ; this was done by means of microscopic observa-
tion of sound- vibrations conducted through a tube. By introducing a
tube, and making our observations by means of a microscopic ear-
mirror constructed for the purpose, we tried to detect a similar spon-
taneous change of disposition in the living ear, but unsuccessfully. I
have, however, subsequently been inclined to doubt whether the
powerful vibrations which are observed in this way, would of them-
selves be decisive of the question, since, unless they were muted, they
could scarcely penetrate into the labyrinth without doing damage.
Consequently, as long as the vibrations cannot be observed with
certainty in a normal living ear, it will scarcely be possible to decide
this question definitely. A method of light-interference might lead to
the desired result. But such a method would have to be of particularly
simple form, if it is to be applicable under the difficult conditions of
the living ear.
280 THE ANALYSIS OF SENSATIONS
range of my own voice. In listening to an orchestral
performance with all the parts, or in having an hallucination
of such a performance, it is impossible for me to think
that my understanding of this broad and complicated sound-
fabric has been effected by my one larynx, which is, more-
over, no very practised singer. I consider the sensations
which, in listening to singing, are doubtless occasionally
noticed in the larynx, a matter of subsidiary importance,
like the pictures of the keys touched which, when I was
more in practice, sprang up immediately into my imagina-
tion on hearing a performance on the piano or organ.
When I imagine music, I always distinctly hear the notes.
Music can no more come into being merely through the
motor sensations accompanying musical performances,
than a deaf man can hear the music by watching the
movements of players. I cannot therefore, agree with
Strieker on this point. (Cp. Strieker, Du langage et de la
musique, Paris, 1885).
Different is my opinion with regard to Strieker's views on
language. (Cp. Strieker, Die Sprachvorstellungen, Vienna,
1880.) It is true that in my own case words of which
I think reverberate loudly in my ear. Moreover, I have
no doubt that thoughts may be directly excited by the
ringing of a housebell, by the whistle of a locomotive, etc.,
and that small children and even dogs understand words
which they cannot repeat. Nevertheless, I have been
convinced by Strieker that the ordinary and most familiar,
though not the only possible way by which speech is
comprehended, is really motor, and that we should be
badly off if we were without it. I can cite corroborations
of this view from my own experience. I frequently see
THE ANALYSIS OF SENSATIONS 281
strangers who are endeavoring to follow my remarks
slightly moving their lips. If a person tells me his
place of residence and I omit to repeat the street
and number of the house after him, I am certain to
forget the address, but with the exercise of this
precautionary measure, I retain it perfectly in memory.
A friend told me recently that he would not read
the Indian drama Urvasi, because he had great diffi-
culty in spelling out the names, and consequently
could not retain them in memory. The dream of
the deaf-mute, which Strieker relates, is intelligible
only from his point of view. In fact, on calm
reflexion this seemingly paradoxical relation is by no
means so remarkable. The extent to which our thoughts
move in accustomed and routine channels is shewn
by the surprise produced by witticisms. Good jokes
would be more frequent if our minds moved less in
ruts. To many the obvious collateral meanings of
words never suggest themselves. Who, for example,
in using the names Smith, Baker, or Taylor thinks of
the occupations designated ! To adduce an analogous
example from a different field, I may state (cp. p. in)
that I immediately recognize writing reflected in a
mirror and accompanying its original, as symmetrically
congruent with the latter, although I am not able
to read it directly, because of my having learned
writing by motor methods, with my right hand.
I can also best illustrate by this example why I do not
agree with Strieker in regard to music : music is related
to speech as ornament is to writing.
282 THE ANALYSIS OF SENSATIONS
12.
I have repeatedly illustrated by experiments, which I
will cite again here, the analogy between fixing the eyes
on points in space and fixing the attention on tones. one
and the same combination of two tones sounds different
according as we fix our attention upon the one or the other.
Combinations i and 2 in the annexed cut have a perceptibly
different character according as we fix our attention on the
higher or on the lower note. Persons not able to transfer
their attention at will will be helped by having one note
sounded later than the other (3, 4). The one sounded last
then draws the attention after it. With a little practice it
is possible to decompose a chord (as, for instance, 5) into
its elements and to hear the constituent tones by themselves
(as in 6). These and the following experiments are better
and more convincingly carried out upon a physharmonica,
on which the notes can be held, than on a piano.
Especially astonishing is the phenomenon produced when
.we cause one note of a chord, on which the attention is
fixed, to be damped. The attention then passes over to
one of the notes nearest to it, which comes out with the
distinctness of a note that has just been struck. The
impression made by the experiment is quite similar to that
which we receive when, absorbed in work, we suddenly
THE ANALYSIS OF SENSATIONS 283
hear the regular striking of the clock emerge into distinct-
ness after having entirely vanished from consciousness. In
the latter case the entire tonal effect passes the threshold of
consciousness, whilst in the former a part is augmented. If
in 7, for example, we fix the attention upon the upper note,
s
r j~*7 '
Fl H
pi H
~P^
1
4
I
A
' X
p t ^ '
letting go, successively from above, the keys damping the
other notes, the effect obtained is approximately that of 8.
If, in 9, we fix the attention on the lowest note, and proceed
in the reverse order, we obtain the impression represented
in 10. The same chordal sequence sounds quite different
according to the part on which the attention is fixed. If,
in 1 1 or 1 2, I fix my attention on the upper note, the timbre
3
12
ry * \\ i
NHr-^- ^^
alone appears to be altered. But if, in II, the attention be
fixed upon the bass, the entire acoustic mass will seem to
sink in depth ; while in 1 2 it will appear to rise if we regard
closely the succession e-f. This makes it quite evident, in
fine, that chords act the part of clangs (or compound notes
embracing both fundamentals and harmonics). The facts
284 THE ANALYSIS OF SENSATIONS
here advanced remind us strongly of the changing impres-
sion received when, in observing an ornamental design, the
attention is alternately fixed on different points.
We may also recall to mind here the involuntary wander-
ing of the attention which takes place during the continuous
and uniform sounding of a note on the harmonium, where
if the note lasts several minutes, all the overtones will of
themselves successively emerge into full distinctness. 1 The
process appears to point to a sort of fatigue for the note on
which the attention has long been fixed. This fatigue,
moreover, is rendered quite probable by an experiment
which I have described at length in another place. 2
The relations in the sphere of tone-sensation, which
I we have here been describing, might be
illustrated perhaps more palpably by some
such parallel as the following. Suppose
that our two eyes were capable of only a
single movement, and that they could only
follow, by changing motions of symmetrical
convergence, the points of a horizontal
straight line lying in the median plane ; and
suppose that the nearest point on this line
Fig. 36.
fixed by the eyes were pure red, and the
point farthest away, corresponding to the position of
parallelism, were pure yellow, while between them lay all
intermediate shades ; then the system of sight-sensations
so constructed would quite palpably resemble the relations
of the sensations of tone.
1 Cp. my Einleitung in die Helmholtzsche Musiktheorie, p. 29.
2 Cp. my Grundlinien der Lehre von den Bewegiingsempfindtingen^
p. 58.
THE ANALYSIS OF SENSATIONS 285
on the view hitherto developed, an important fact, which
we shall now consider, remains unintelligible, though its
explanation is absolutely necessary if the theory is to lay
any claim to completeness. If two series of tones be begun
at two different points on the scale, but be made to main-
tain throughout the same ratios of vibration, we recognize
in both the same melody, by a mere act of sensation, just
as readily and immediately as we recognize in two geome-
trically similar figures, similarly situated, the same form.
Like melodies, differently situated on the scale, may be
termed tonal constructs of like tonal form, or they may be
termed similar tonal constructs. It is easy to convince
oneself that this recognition is not connected exclusively
with the employment of ordinary musical intervals or of any
comparatively simple ratio of vibration-numbers in common
use. If the open strings of a violin, or of any other instru-
ment with more than one string, be "tuned to any discon-
nected notes we please, and a strip of paper, divided up
into any complicated series of ratios, be fastened to the
finger-board, we can play the notes indicated in any order
(or slide from one to the other), first on one string and
then on the others. Now although the resultant sound
may have no sense as music, we can recognize the melody
as the same on each string. The experiment would not
be any more convincing, if we deliberately divided the
finger-board into irrational intervals. Indeed in practice
the result would be only approximate. The musician could
still maintain that he heard intervals that were approximate
or intermediate to the familiar musical intervals. Untrained
286 THE ANALYSIS OF SENSATIONS
song-birds use the musical intervals only in exceptional
cases.
Even in a series of only two tones, the sameness of the
ratios of vibration is at once recognized. Thus in the
series c-f, d-g, e-a, etc., the notes which have all the same
ratios of vibration (3 : 4), are immediately recognized as
like intervals, as fourths. Such is the fact, in its simplest
form. The ability to pick out and recognize intervals is
the first thing required of the student of music who is
desirous of becoming thoroughly familiar with his subject.
In a little work, 1 well worth reading, by E. Kulke, mention
is made, bearing on this point, of an original method of
instruction by P. Cornelius a notice which I will now
supplement by the following communication made to me
orally by Kulke himself. According to Cornelius, it is a
great help in the recognition of intervals to make note of
particular pieces of music, folk-songs, etc., which begin
with these intervals. The overture to TannMuser, for
example, begins with a fourth. If I hear a fourth I at once
remark that the tone-sequence might be the beginning of
the overture to Tannhauser, and by this means I recognize
the interval. In like manner, the overture to Fidelia
(No. i) may be used as the representative of the third ; and
so on. This excellent device, which I have put to the test
in my lectures on acoustics and have found very effective,
apparently complicates matters. one would naturally
suppose that it would be easier to make note of an interval
than of a melody. Nevertheless, a melody offers a greater
hold to memory than does an interval, just as an individual
1 E. Kulke, Ueber die Umbildung der Melodic. Ein Beitrag zur
Entwicklungslehre, Prague, Calve, 1884.
THE ANALYSIS OF SENSATIONS 287
countenance is more easily remarked and associated with a
name than is a certain facial angle or a nose. Every one
makes note of faces and associates with them names ; but
Leonardo da Vinci arranged noses in a system.
14.
Just as every interval in a sequence of tones is made per-
ceptible in a characteristic manner, so it is with the harmonic
combinations of tones. Every third, every fourth, every
major or minor triad has its characteristic color, by which it
is recognized independently of the pitch of the fundamental,
and independently of the number of beats, which rapidly
increases with increasing pitch.
A tuning-fork held before one ear is very feebly heard by
the other ear. If two slightly discordant, beating tuning-
forks are held in front of the same ear, the beats are very
distinct. But if one of the forks be placed before one ear,
and the other before the other, the beats will be greatly
weakened. Two forks of harmonic interval always sound
slightly rougher before one ear. But the character of the
harmony is preserved when one is placed before each ear. 1
The discord also remains quite perceptible in this experi-
ment. Harmony and discord are, however, not determined
by beats alone.
In melodic as well as in harmonic combinations, notes
whose rates of vibrations bear to one another some simple
ratio, are distinguished (i) by their agreeableness, and (2)
by a sensation characteristic of this ratio. As for the
1 Cp. Fechner, Ueber einige Verhtiltnisse des binocularen Se/iens,
Leipzig, 1860, p. 536. I have myself often tried such experiments.
288 THE ANALYSIS OF SENSATIONS
agreeable quality, there is no denying that this is partly
explained by the coincidence of the overtones, and, in the
case of harmonic combination, by the consequent efface-
ment of the beats, resulting always where the ratios of the
numbers representing the vibrations satisfy certain definite
conditions. But the experienced and unprejudiced student
of music is not entirely satisfied with this explanation. He
is disturbed by the preponderant r61e accorded to the
accident of acoustic color, and notices that tones further
stand to each other in a positive relation of contrast, like
colors, except that, in the case of colors, no such definite
agreeable relations can be specified.
The fact that a sort of contrast really does exist among
tones almost forces itself upon our notice. A smooth, un-
changing tone is something very unpleasing and colorless,
like a single uniform color enveloping our entire surround-
ings. A lively effect is produced only on the addition of
a second tone, a second color. In like manner, if we
cause a tone gradually to mount in pitch, as in experiments
with the siren, all contrast is lost. Contrast exists, how-
ever, between tones farther apart, and not merely between
those immediately following one another, as the accompany-
ing example will shew. Passage 2 sounds quite different
after i from what it does alone, 3 sounds different
from 2, and even 5 different from 4 immediately
following 3.
THE ANALYSIS OF SENSATIONS 289
16.
Let us turn now to the second point, the characteristic
sensation corresponding to each interval, and ask if this
can be explained on our present theory. If a fundamental
n be melodically or harmonically combined with its third
m, the fifth harmonic of the first note (5^) will coincide
i
C c g c e g b-flat c
n zn 3 4 5* 6n 7* 8n
e b e g-sharp b d
zm yn qm yn 6fft jtn
t = = =
F f c f a c e-flat f
n 2 3 4 5 () 7 8
t = = = =
A a e a c-sharp e g a
m -im yn ^m $m bnt -jm 8f
with the fourth of the second note (40*). This, according
to the theory of Helmholtz, is the common feature char-
acterizing all third combinations. If I combine the
notes Cand E, or F and A, representing their harmonics
in the above table, then, as a fact, in the one case the
harmonics marked ] and in the other those marked j
coincide ; and in both cases the coincidence is between
the fifth harmonic of the lower and the fourth harmonic of
the higher note. Be it noted, however, that this common
feature exists solely for the understanding, being the result
2go THE ANALYSIS OF SENSATIONS
of a purely physical and intellectual analysis, and has
nothing to do with sensation. For sensation the real
coincidence in the first case is between the e's, and in the
second between the a's, which are entirely different notes.
on the assumption that there exists for every distinguish-
able rate of vibration an appropriate specific energy, we
are obliged, more than on any other theory, to ask where
is the common component of sensation hidden that
characterizes every third combination ?
I must insist on this distinction of mine not being re-
garded as a piece of pedantic hair-splitting. I propounded
the question involving it about twenty years ago, at the same
time with my question as to wherein physiological similarity
of form, as distinguished from geometrical, consisted ; and
the former is not a whit more unnecessary than was the latter,
of which the superfluity, too, in the issue, was disproved. If
we are to allow a physical or mathematical characteristic of
the tierce-interval to stand as a mark of the tierce-sensation,
then we should content ourselves, as Euler did, 1 with the
coincidence of every fourth and fifth vibration a concep-
tion which was, after all, not so bad, as long as it could be
believed that sound continued its course in the nerve-tracts,
also, as periodic motion, a view which even A. Seebeck 2
1 Euler, Tentamen novce theories musicce^ Petropoli, 1739, p. 36.
2 I cannot understand how any one can still maintain the theory of
the temporal coincidence of impulses. At one time I replaced A.
Seebeck's experiment by what I believe to be a better procedure
(" Ueber einige der physiologischen Akustik angehorige Erscheinun-
gen," Berichte der Wiener Akademie, 26th June 1864), but I never could
detect any periodicity in the nerve-process connected with sensation.
At that time it was not known that beats are never observed between
a subjective tone and an adjacent objective tone, or between subjective
ones ; but the fact cannot now be doubted. Cp. Stumpf's interesting
THE ANALYSIS OF SENSATIONS 291
(Pogg. Ann., Vol. LXVIII.) regarded as possible. With
regard to this particular point, Helmholtz's coincidence of
5 and $m is in no respect less symbolical and does not
offer greater enlightenment.
So far I have presented my arguments with the convic-
tion that I should not find it necessary to make a single
retrograde step of importance. This feeling does not accom-
pany me in the same measure in the development of the
following hypothesis, which, in all its essential features,
was suggested to me a long time ago. Yet the hypothesis
may at least serve to clear up and illustrate, from the
positive side also, the requirement which I believe a more
complete theory of tone-sensations is bound to meet. I
will first expound my view in the form in which it appeared
in the first edition of this book.
Let us suppose that it is an extremely important vital
condition for an animal of simple organization to perceive
slight periodic motions of the medium in which it lives.
If (owing to the relatively excessive size of its organs, and
its consequent lack of receptivity for such rapid changes)
paper on " Beobachtungen liber subjective Tone und tiber Doppelt-
horen " (Zeitschrift fur Psychologic und Physiologic der Sinnesorgane,
Vol. XXL, pp. 100-121). The subjective tones that arise in my ear
generally last too short a time for me to experiment with them. Still
I did succeed not long ago (1906) in getting to the piano with a very
clear and constant c-sharp, and convincing myself that when a c-sharp
a shade deeper was lightly struck on the piano, no beats were demon-
strable. For me, indeed, this demonstration was superfluous, for I
hold the opposite supposition to be physiologically inadmissible. But
Stumpf s observations on the consonance and dissonance of subjective
tones without beats are very important.
292 THE ANALYSIS OF SENSATIONS
change of attention is too sluggish, and the period of the
oscillations is too short, or their amplitude too small, to
permit the single phases of the excitation to enter con-
sciousness, it may nevertheless be possible under certain
conditions for the animal to perceive the accumulated sensa-
tion-effects of the oscillatory stimulus. The organ of hear-
ing will outstrip the organ of touch. 1 Now an end-organ
capable of vibration (say an auditory cilium) responds, by
virtue of its physical qualities, not to every rate of vibration,
nor to one only, but ordinarily to several, at a considerable
distance apart. 2 Therefore, as soon as the whole continuum
of rates of vibration between certain limits becomes of
importance for the animal, a small number of end organs
no longer suffices, but the need of a whole series of such
organs of graduated capacity arises. At first the organ of
Corti and the basilar membrane were regarded by Helmholtz
as such a system.
It can hardly be expected, however, that a member of
such a system will respond to only one rate of vibration.
on the contrary, we should expect that it would respond
with enfeebled but graduated intensity (perhaps from being
divided by nodes) to the rates of vibration 2n, 3^, 4, etc.,
as also'^to the rates of vibration /2, /3, /4, etc. Inasmuch
1 It is questionable therefore whether animals which have so small a
measure of time that their voluntary movements produce a musical note
hear in the ordinary sense, or whether with them it is not rather
touch which makes on us the impression of hearing. Cp., for example,
the admirable experiments and observations of V. Graber (" Die
Chordotonalen Organe," Arch, fur Microskop. Anat., XX., p. 506).
Cp. also my Beuoegungsempfindungen, p. 123. This conjecture has
subsequently been confirmed in many ways. See Pop-ii lar-wis sen-
se haft liche Vorlesitngen, 3rd ed., p. 401.
2 As V. Hensen, for example, has observed.
THE ANALYSIS OF SENSATIONS 293
as the assumption of a special energy for each rate of
vibration has proved untenable, we may imagine, agreeably
to what has been said above, that in the first place, only two
sensation-energies, say, Dull (D) and Clear (C), are excited.
The resultant sensation we will represent symbolically
(somewhat as we do in mixed colors) by pD + qC ; or,
making / + ^ = i and regarding q as a function f(n) of the
rate of vibration, 1 by [T -f(n)} D+f(n) C. The sensation
arising will now correspond to the number of the vibrations
of the oscillatory stimulus, to whatever member of the series
of end-organs the stimulus may be applied. And con-
sequently our earlier view will not be materially disturbed
by the new hypothesis. For, since the member n responds
most powerfully to n, and only in a much more enfeebled
degree to 2#, $n, or to n/2, n/$, R n vibrating with n even
in case of an aperiodic impulse, therefore the sensation
[i -/()] D+f(n) C will still be predominantly associated
with .
Well-attested cases of double hearing (cp. Stumpf, loc.
tit., p. 266 et seq.) point forcibly to the conclusion that
the ratios in which D and C are disengaged are dependent
upon the end-organ, and not upon the rate of vibration
a conclusion which would also not affect our theory.
A member R n , accordingly, responds powerfully to #,
and also, though more weakly, to 2, 3^, .... n/2,
n/3 .... with the sensations belonging to these rates of
vibration. It is, however, extremely improbable that exactly
the same sensation is excited whether R n responds to n, or
whether R n responds to . on the contrary, it is probable
that every time the members of the series of organs respond
1 Thus, to take a very simple example, we might make /() k. log. .
294 THE ANALYSIS OF SENSATIONS
to a partial tone, the sensation receives a weak supple-
mentary coloring, which we will represent symbolically, for
the fundamental tone by Z 1? for the overtones by Z 2 , Z 3 ,
. . . ., and for the undertones by Z^ Zi, . . . . on this
supposition, sensations of tone would be somewhat richer in
composition than would follow from the formula [i -f(n)] D
+ f( n ) The sensations which the series of end-organs,
as excited by the fundamentals, yields, constitute a province
with the supplementary coloring Z v the excitation of the
same series by the first overtone yields a special province
of sensation with the supplementary coloring Z 2 , etc. The
Z's may be either unchanging elements, or may themselves,
again, consist of two components, U and F, and form series
representable by [i -/()] U+f(n) F. But at present the
decision on this last point is immaterial.
It is true that the physiological elements Z 15 Z 2 , . . . .
have yet to be found. Yet the very perception that they
have to be sought seems to me of importance. Let us see
what form the province of tone-sensations would take on
if we regarded Zj, Z 2 , .... as given.
We will take as example a melodic or harmonic major-
third combination, whose rates of vibration are n = ^p
and m = $p; the lowest of the overtones common to the
two is 5 = 4m = 20^, the highest of the undertones common
to the two is p. Then we obtain the table on the
following page.
Thus in the third combination, the supplementary sensa-
tions Z 4 , Z 5 , and Z^ Zi, which are characteristic of the
third, make their appearance even when the notes contain
no overtones, while the former (Z 4 , Z 5 ) are strengthened
when, either in the open air or at least in the ear, over-
THE ANALYSIS OF SENSATIONS 295
tones do occur. The diagram may be easily generalized
to include any interval. 1
These supplementary colorings, though scarcely notice-
able in single tones, or in running continuously through
the scale, will accordingly become conspicuous in combina-
tions of tones having certain ratios of rate of vibration,
The members of
the series of end-
RP
R$p
R$p
Rzop
organs :
-a c
S|
respond to the rates
of vibration ;
4A5/
4*
5/
*a*
1L
4
SS-5 4
M
with the supple-
d w
mentary sensa-
Zi, Z &
z\
z l
Z!,Z,
|- S
tions :
*i
they also respond
g
to the rates of vi-
20/> ~5(4/)
20/ = 4(5^)
|
bration :
*^rf
with the supple-
g" S
mentary sensa-
^ 5
Zi
gS,
tions ;
just as the contrasts of faintly colored, almost white lights
become vivid when such lights are brought together. And,
1 The above exposition will be found in a rather conciser and slightly
different form in my note "Zur Analyse der Tonempfindungen "
(Sitzungsberichte der Wiener Akademie, December 1885), where I
have tried to analyse sensations of tone on the analogy of sensations
of color, of which the analysis has been carried very much further.
Every vibration-number disengages a few specific energies in a ratio
which depends on the vibration-number in question, The excitability
of these energies is different at different points on the retina. Analogous
relations are assumed mutatis imitandis for sensations of tone. It
296 THE ANALYSIS OF SENSATIONS
furthermore, the same contrast-colorings always correspond
to the same ratios of rate of vibration, no matter what the
pitch.
In this manner it is intelligible how tones may receive,
by melodic and harmonic combination with others, the
most varied colorings, which are wanting to them when
singly sounded.
The elements Z lt Z 2 . . . must not be conceived as
unvarying and fixed in number. on the contrary, it is
to be supposed that the number of perceptible Z's depends
on the organization, on the training of the ear, and on the"
attention. According to this conception, the ear does not
directly cognize ratios of rate of vibration but only the
supplementary colorings conditioned by these ratios. The
tonal series symbolically represented by [i -f(n)]D +f(n} C
is not infinite but limited. Since / (n) may vary between
the values o and i, D and C, where they are the sensations
corresponding to the lowest and highest tones, are the
end-terms of the series. If the number of vibrations
sinks considerably below or rises considerably above that
of the fundamental of the extreme term of the series, a
weak response only will take place, but no alteration of
the quality of the sensation. Further, the sensation of
the intervals must disappear in the neighborhood of the
seemed originally that in both cases there must be an infinite variety
of sensations corresponding to the infinite variety of the physical
stimulus. But in both cases psychological analysis leads to the con-
clusion that a smaller number of sensations is to be assumed, and that,
on the principle of parallelism, we have to think of these sensations,
not as immediately dependent on the complicated physical stimulus,
but as immediately dependent on the psycho-physical process which is
as simple as they are themselves.
THE ANALYSIS OF SENSATIONS 297
two limits of hearing ; first, because, in general, differences
between sensations of tone cease at this point, and, secondly,
because at the upper limit the members of the series
capable of being excited by the undertones are lacking,
while at the lower limit those which react on the overtones
are lacking.
Passing in review again the position at which we have
arrived, we see that with few exceptions the conclusions
reached by Helmholtz may be all retained. Noises and
composite sounds may be decomposed into musical tones.
To every distinguishable rate of vibration there corre-
sponds a particular nervous end-organ. In place of the
numerous specific energies required by this theory, how-
ever, we substitute two only, which render the relationship
of all tonal sensations intelligible, and which, by the role
which we assign to the attention, likewise enable us to
keep perceptually distinct, several tones when sounded
together. By the hypothesis of the multiple response of
the members of the series of end-organs, and by that of
supplementary acoustic colorings, the significance of
accidental acoustic color is diminished, and we get a
glimpse of the direction in which, notably on the ground
of musical facts, the positive characteristics of intervals
are to be further investigated. Finally, the latter con-
ception supplies Von Oettingen's principle of duality
with a foundation which might perhaps commend
itself to this investigator himself as preferable to his
assumption of "memory"; while at the same time it
becomes manifest why the duality cannot be a perfect
symmetry.
298 THE ANALYSIS OF SENSATIONS
18.
I have expressly described the theory of the multiple
response of the series of end-organs, as well as the theory
of supplementary colorings, as a "hypothesis," and I have
put forward this hypothesis merely with the object of
illustrating the meaning of the postulates resulting from
psychological analysis, and of perhaps stimulating others
to a more successful attack on the problem. I am there-
fore not surprised to find that other writers do not agree
unreservedly with my attempt. But that this hypothesis is,
as Stumpf says, 1 useless and quite unsuited to its purpose,
I cannot admit. The coincidence of the supplementary
colorings Z 4 , Z 5 , or Z t Zj, in one and the same nerve, is
not merely a physical, but also a psycho-physical fact. It
can scarcely be a matter of indifference that the sensation
of a mixed coloring is determined by a single element. on
the contrary, it seems to me that what I am looking for,
namely an explanation of the definite coloring of the
intervals, and also what Stumpf is looking for, namely
an explanation of fusion, would actually be represented
by the partial coincidence which I assume, even without
overtones. - Stumpf s further assertion that, in the case of
notes with overtones, there is no difficulty in understanding,
on Helmholtz's theory, the similarity of like intervals, rests
upon a misapprehension of my criticism of Helmholtz.
It will satisfy no one to be told that overtones of equal
strength coincide in the case of two tierces, since what is
in question is the qualitative similarity of the sensations.
1 C. Stumpf, Beitrage z^^r Akustik imd Musikwissenschaft^ Heft I,
pp. 17, 18.
THE ANALYSIS OF SENSATIONS 299
If the recognition of a melodic tierce-interval were imme-
diately intelligible, it would of course be unnecessary to
look for any special explanation of why we recognize the
harmonic combination of tierces. But inasmuch as Stumpf
himself holds that the melodic steps are characterized by
the harmonic combination, this view would involve a vicious
circle. on my theory also, the fact of melodic and harmonic
selection of definite ratios of vibration-numbers leads to the
same problem. My hypothesis inclines towards the theory
of resonance, and according to Stumpf is to be rejected
on that very account. I will presently deal more particu-
larly with this last point.
19.
There has been much discussion of the physical pro-
cesses involved in audition, and, in particular, of the
function of the parts of the middle ear. In spite of this,
it would seem that an unprejudiced revision of the physical
theory of audition is urgently needed. The question has
been raised whether the auditory ossicles vibrate as a
whole, or whether the sound-waves pass through them.
E. H. Weber decides in favor of the former view, which
has been experimentally confirmed by Politzer, while I
was probably the first to establish it on a theoretical basis. 1
For if the dimensions of the ossicles in comparison with
the length of the sound-waves in question are, as regards
their material, very small (as is actually the case), there
can be no doubt that practically the same phases of move-
1 Mach, " Zur Theorie des Gehororgans," Sitzungsberichte der Wiener
Akademie, Vol. LVIIL, July 1863. Also Helmholtz, Die Mechanik
der Gehorknochelchen, 1869.
300 THE ANALYSIS OF SENSATIONS
ment occur throughout the whole extent of the ossicles,
and that consequently they must move as a whole. It
has occurred to some inquirers to transfer the movements
of the ossicles to the fluid of the labyrinth. But patho-
logical investigations teach us that, even without the
co-operation of the ossicles and the membrana tympani,
the hearing may remain quite good, provided that the
labyrinth is in order. The ossicles and tympanum seem
only to be important when what is in question is the trans-
ference to the labyrinth of very faint movements of the
air ; in that case the reduction of the pressure falling upon
the whole surface of the membrana tympani to the small
stirrup-footplate seems to be necessary. Otherwise, sound-
waves can be carried to the labyrinth by way of the cranial
bones also. If sounding bodies, such as tuning-forks, are
placed on different parts of the head, it can be shewn that
the direction of the sound-waves that penetrate into the
labyrinth does not play any important part. Again, all
dimensions of the sound-perceiving apparatus are so small
in comparison with the audible soundwaves, and the
velocity of sound in the bones and the labyrinthine fluid
is so great, that the whole extent of the labyrinth only
contains room for one perceptible wave-phase at any one
moment. The result of all this is, that it is not the move-
ments and the direction of movement, but the variations
of pressure which arise in the labyrinth almost synchron-
ously, that are to be regarded as the decisive stimulus that
excites sensation.
Nevertheless let us consider the movement which can be
set up in the labyrinth by the movements of the stirrup-
plate. We may first imagine all the soft parts to be taken
THE ANALYSIS OF SENSATIONS 301
out, and the whole space bounded by the osseous wall to
contain nothing but fluid. The movement that can find
room here is a periodical current passing from the oval to
the round window and vice versa, the form of which, since
the velocity of the disturbance vanishes in proportion to the
velocity of the sound, will be almost entirely independent
of the period. If the surfaces of the two windows are con-
ceived as positive and negative electrodes, and as conducting
the fluid, then the lines of the electric current will coincide
with the lines of the periodic current. Now this state of
things will not suffer any substantial change, if the difference
between the specific weight of the soft parts and that of the
fluid in which they are immersed is very small. It is the
mass of the fluid that is of predominant importance. The
fact that particular constructions can', according to the pitch,
take on a special local state of vibration in spite of the fluid,
need scarcely be discussed. The quantitative relations are
here quite different from what they are in the case of strings
or membranes in air.
Consequently, Ewald's new theory of audition 1 is, in my
opinion, no more tenable than the theory of Helmholtz as
to the fibres of Corti and the elective vibrations of the
basilar membrane. If in Ewald's experiments a membrane
coated with oil shews, when the coat is comparatively thick,
no clear divisions any longer, it would completely fail to
shew any if it were immersed in a fluid, much more if the
dimensions were proportionately reduced. We must, how-
ever, insist that Ewald's theory is otherwise appropriate in
many respects, and that it would offer many advantages.
For instance, in the case of harmonic intervals, even when
1 Ewald, Eine neue Hortheorie^ Bonn, 1899.
302 THE ANALYSIS OF SENSATIONS
overtones are absent, the membranes display coincidences
of the node-lines. Thus this theory seems to fulfil a part
of the above mentioned postulates. Unfortunately it is
physically inadmissible, quite apart from further difficulties
which it is also unable to solve. I need scarcely say that I
do not presume to dismiss so admirable and laborious a
piece of work in a few words, but at the same time I cannot
refrain from stating my objections to it.
Shortly after the publication of the fourth edition of this
book, which contained the foregoing passages expressing my
doubts as to the vibration of membranes in fluids, Ewald
published his experiments with the camera acustica. 1 He
immersed in water a delicate membrane, of about the
dimensions of the basilar membrane, and succeeded in
acoustically setting up in it continuous vibrations with clear
nodal divisions corresponding to the pitch. This shewed
that my conjecture was wrong, and gave me cause to reflect
in what point I had been mistaken. I then remembered
the very small nodal divisions which, years before, I had
myself observed in fluid membranes. 2 I also recalled
Friesach's experiments with strings immersed in water, 3 the
result of which had been to shew that immersion in water
acts as an enlargement of the string's mass, since the fluid
in the immediate neighborhood of the string accompanies
its vibrations, moving synchronously to and fro in extremely
short paths. It is therefore quite conceivable that the
labyrinthine fluid vibrates to and fro as a whole, and that
1 Ewald, Pfliiger's Archiv, 1903, Vol. XCIII., p. 485.
2 Optisch-akustische Versuche, Prague, 1872, p. 93,
3 Friesach, Berichte der Wiener Akademie^ 1867, Vol. LVL, 2nd
part, p. 316.
THE ANALYSIS OF SENSATIONS 303
nevertheless the velocity of propagation in the membrane,
which is very much smaller, appears in the labyrinthine
fluid in the form of stable vibrations of the membrane. If
the existence of such vibrations of the membrane is proved,
Ewald's theories gain greatly in value. I should like,
further, to refer here to two papers by Stohr which seem to
me to contain the germs of ideas which would repay
development. 1
20.
The difficulty of setting the theory of resonance on a
sound physical basis has probably, as it seems to me, been
felt by everyone who has studied it, and not least acutely
by its originators. But at the same time it was recognized
that, if it was given up, the key to the problem of the
analysis of sounds and to a clear and simple doctrine of
tone-sensations would be lost. Hence the frantic attempts
to save the theory of resonance. L. Hermann 2 seems to
me to speak very much to the point, when he says that
we cannot do without some sort of theory of resonance, but
that this need not necessarily be a physical theory, but may
also be a physiological theory. We may make, with him,
the plausible assumption that the nervous organs per se
1 Stohr, " Ueber Unterbrechungstone," Deutsche Revile, July, 1904.
Mach and Kessel some time ago pointed out the necessity of attacking
the problems of acoustics from the point of view of asymmetry ; see
"Die Funktion der Trommelhohle," Berichte der Wiener Akademie,
Vol. LXVI., 3rd part, 1872; Stohr, " Klangfarbe oder Tonfarbe,"
SUdde^^tsche Monalshefte, Munich and Leipzig, July 1904. In this
paper Stohr is aiming, though by a different route, at a goal not far
removed from my own.
2 Hermann, Pfliiger's Archiv, Vol. LVL, pp. 494 sqq., 1894.
304 THE ANALYSIS OF SENSATIONS
are peculiarly sensitive to stimuli with a definite period. 1
It cannot exactly be elastic forces that impel the organ
back to its position of equilibrium, but we may think of a
state of equilibrium which is of an electrical or chemical
nature, the deviations from it standing to one another in
the relation of the positive to the negative sign. And
further, there may be a connexion between these organs,
by means of which one can act as a stimulus upon another.
In this way a reasonable prospect seems to be opened up
of making up for the loss of the physical theory. I cannot
here attempt to reproduce Hermann's arguments com-
pletely and accurately, but must content myself with
referring the reader to his paper.
one point, however, we may consider more closely.
When two wave-shaped pendular vibrations with vibration-
numbers , ', co-operate, there then arise beats which
may be regarded as a rising and sinking of the tone, n or
n' (n' ri) times a second. But it is never possible to
regard the movement of the air as such a movement as
could contain the wave-vibration, that is to say, the tone
n' - n. Fven a physical resonator with the vibration-
number n' - n can never be excited by such beats, whether
they are fast or slow. Indeed, it is easy to see, when one
imagines or draws the course of the beats, that in the long
run precisely as many and as strong positive and negative
impulses must take place as there are vibrations (#' - n) of
the resonator. In the first half of the time, also, the
impulses are equal to and of the same direction as the
1 Perhaps this assumption would still remain valuable if it also suc-
ceeded in providing a basis for a satisfactory physical theory of
resonance.
THE ANALYSIS OF SENSATIONS 305
impulses in the second half. An effectual summation is
therefore excluded. It would only be possible if the
resonator could be made more receptive of one kind of
impulse than of the other, and more receptive in the first
half of the duration of its vibration. We can easily see
how this way of considering the matter involves the re-
jection of Young's explanation of combination tones by
means of rapid beats, and leads, on the other hand, to
Helmholtz's theory of combination tones, while preserving
the theory of resonance. It would seem, however, that
the physical relations which Helmholtz had to assume do
not exist in the circumstances under which combination
tones are heard. But it is quite conceivable that a nervous
organ should be unequally receptive of opposite impulses,
and likewise should be receptive in different degrees at
different stages of its excitation. For an organ does not
simply follow the forces that act upon it, but contains a
store of energy upon which those forces only act by liberat-
ing the energy. In this way Young's mistake, and the
presumably unsuccessful attempt of Helmholtz to improve
on Young's theory, will have led to an important new point
of view.
21.
The theory of Helmholtz as to tone-sensations seemed,
when it was first promulgated, to be an admirably complete
and classical achievement. Yet, on a fundamental exami-
nation, it has not been able to stand against criticism.
And this criticism was in no sense captious, as is suffi-
ciently evident from the fact that the attacks of the different
critics, in spite of all individual peculiarities, were directed
306 THE ANALYSIS OF SENSATIONS
against the same points and took the same direction. The
result of all this criticism seems to be that the main problem
has been put back almost to the point at which it stood
before Helmholtz wrote. The effect of this might be
tragic, if it were ever legitimate to look at the matter from
the point of view of a single person.
But the achievement of Helmholtz, open to attack
though it may be on certain sides, must not be underrated.
His work, apart from the positive increase of knowledge
which we owe to it, has brought life and movement into
the whole question ; it has encouraged inquirers to make
new experiments, and has provided the stimulus for a mass
of new investigations ; new prospects have been opened up,
and possible ways of going wrong have been definitely
closed for ever. New experiments and criticisms are
made all the easier by the existence of some positive work
from which to take their start.
In thinking that a task, which provides ample work for
psychologists and physiologists as well as for physicists,
could be mastered, in all its main features, from physical
points of view, Helmholtz was doubtless under a delusion.
Even those friends and contemporaries of his who, about
the middle of the last century, founded the physical school
of physiology in co-operation with him, have had to recog-
nize that the fragment of inorganic physics which we have
conquered, is far from being the whole world. The
"Doctrine of Tone-Sensations" is the speculation of a
genius, the ｅxpression of an artistic intuition, which points
the way though it be only by the symbolism of a physical
analogy, and as in a picture along which further research
will have to advance. We must therefore be careful not to
THE ANALYSIS OF SENSATIONS 307
throw overboard much that is valuable along with the
deficiencies that have to be set aside. For what reasons
Helmholtz himself took so little notice of criticism, I do
not know. But in the last disposition which he made,
according to which the text of the Tone- Sensations was
to remain unaltered after his death, I think that he acted
rightly.
22.
To a person accustomed to looking at things from the
point of view of the theory of evolution, the high develop-
ment of modern music and the spontaneous and sudden
appearance of great musical talent seem, at first glance, a
most singular and mysterious phenomenon. What can this
remarkable development of the power of hearing have to do
with the preservation of the species? Does it not far
exceed the measure of the necessary or the merely useful ?
What can possibly be the significance of a fine discrimina-
tion of pitch ? Of what use to us is the sense of intervals,
or of the acoustic colorings of orchestral music ?
As a matter of fact, the same question may be proposed
with reference to every art, no matter from what province
of sense its material is derived. The question is pertinent,
also, with regard to the intelligence of a Newton, an Euler,
or their like, which apparently far transcends the necessary
measure. But the question is most obvious with reference
to music, which satisfies no practical need and for the most
part depicts nothing. Music, however, is closely allied to
the decorative arts. In order to be able to see, a person
must have the power of distinguishing the directions of lines.
If he has a fine power of distinction, such a person may
308 THE ANALYSIS OF SENSATIONS
acquire, as a sort of collateral product of his education, a
feeling for agreeable combinations of lines. The case is the
same with the sense of color-harmony following upon the
development of the power of distinguishing colors, and so,
too, it undoubtedly is with respect to music.
We must bear in mind that what we call talent and
genius, however gigantic their achievements may appear to
us, constitute but a slight departure from normal endow-
ment. Talent may be resolved into the possession of
psychical power slightly above the average 'in a certain
province. And as for genius, it is talent supplemented by
a capacity of adaptation extending beyond the youthful
period, and by the retention of freedom to overstep routine
barriers. The naivety of the child delights us, and produces
almost always the impression of genius. But this impres-
sion as a rule quickly disappears, and we perceive that the
very same utterances which, as adults, we are wont to
ascribe to freedom, have their source, in the child, in a
lack of fixed character.
Talent and genius, as Weismann has aptly shown, 1 do
not make their appearance slowly and by degrees in the
course of generations ; nor can they be the result of ac-
cumulated effort and practice on the part of ancestors ; but
they manifest themselves spontaneously and suddenly.
Taken in connexion with what has been said above, this,
too, is intelligible, if we will but reflect that descendants are
not exact reproductions of their immediate ancestors, but
exhibit the qualities both of their immediate and of their
more distant ancestors and relatives with some variations,
1 Weismann, Ueber die Vererbung. Jena, 1883 (English translation,
Clarendon Press, Oxford, 1889), p. 43.
THE ANALYSIS OF SENSATIONS 309
now slightly diminished, now slightly augmented in amount.
The comparison of several children of the same two parents
is very instructive on this point. To deny the influence of
pedigree on psychical dispositions would be as unreasonable
as to reduce everything to it, as is done, whether from
narrow-mindedness or dishonesty, by modern fanatics on
the question of race. Surely everyone knows from his own
experience what rich psychical acquisitions he owes to his
cultural environment, to the influence of long vanished
generations, and to his contemporaries. The factors of
development do not suddenly become inoperative in post-
embryonic life. 1
1 Cf. the sound and sober view of R. Wallaschek, Anfdnge der
Tonkunst) Leipzig, 1903, pp. 291-298.
XIV. INFLUENCE OF THE PRECED-
ING INVESTIGATIONS on OUR
CONCEPTION OF PHYSICS. 1
i.
WHAT gain does physics derive from the preceding in-
vestigations ? In the first place, a very widespread
prejudice is removed, and with it, a barrier. There is no rift
between the psychical and the physical, no inside and outside,
no " sensation " to which an external " thing," different from
sensation, corresponds. There is but one kind of elements,
out of which this supposed inside and outside are formed
elements which are themselves inside or outside, according
to the aspect in which, for the time being, they are viewed.
The world of sense belongs both to the physical and the
psychical domain alike. As, in studying the behaviour of
gases, by disregarding variations of temperature we reach
Mariotte's law, but by expressly considering them, Gay
1 I have partly discussed the questions considered in this chapter,
before (see my History and Root of the Principle of the Conservation
of Energy \ translated by P. E. B. Jourdain, Chicago, Open Court
Publishing Co., 1911, and also the essay on "The Economical Nature
of Physical Inquiry," first published in 1882, and now in my Popular
Scientific Lectures, Chicago. 1894, and see my Mechanik and
Warmelehre). With regard to the idea of concepts as labor-saving
instruments, the late Prof. W. James directed in conversation my
attention to points of agreement between my writings and his essay
on "The Sentiment of Rationality" (Mind, Vol. IV., p. 317, July
1879). This essay, written with refreshing vigor and impartiality, will
be perused by everyone with pleasure and profit.
310
THE ANALYSIS OF SENSATIONS 311
Lussac's, while throughout our object of investigation
remains the same ; so, too, we are studying physics in its
broadest signification when in searching into the connexions
of the world of sense we leave our own body entirely out
of account; whereas we are studying the psychology or
physiology of the senses when we direct our main attention
to the body and above all to our nervous system. Our
body, like every other, is part of the world of sense ; the
boundary-line between the physical and the psychical is
solely practical and conventional. If, for the higher pur-
poses of science, we erase this dividing-line, and consider all
connexions as equivalent, new paths of investigation cannot
fail to be opened up.
We must regard it as an additional gain that the physicist
is now no longer overawed by the traditional intellectual
implements of physics. If ordinary "matter" must be
regarded merely as a highly natural, unconsciously con-
structed mental symbol for a relatively stable complex of
sensational elements, much more must this be the case
with the artificial hypothetical atoms and molecules of
physics and chemistry. The value of these implements for
their special, limited purposes is not one whit destroyed.
As before, they remain economical ways of symbolizing
experience. But we have as little right to expect from
them, as from the symbols of algebra, more than we have
put into them, and certainly not more enlightenment and
revelation than from experience itself. We are on our
guard now, even in the province of physics, against over-
estimating the value of our symbols. Still less, therefore, will
the monstrous idea of employing atoms to explain psychical
processes ever get possession of us; seeing that atoms
312 THE ANALYSIS OF SENSATIONS
are but the symbols of those peculiar complexes of sensa-
tional elements which we meet with in the narrow domains
of physics and chemistry.
2.
The fundamental views of mankind are formed by a
natural process of adaptation to a narrower or wider sphere
of experience and thought. It may be that the physicist is
still satisfied with the notion of a rigid matter, of which the
only changes are movements, or changes of place. Of such
a thing as this the physiologist or psychologist can make
nothing at all. But any one who has in mind the gather-
ing up of the sciences into a single whole, has to look for a
conception to which he can hold in every department of
science. Now if we resolve the whole material world into
elements which at the same time are also elements of the
psychical world and, as such, are commonly called sensa-
tions ; if, further, we regard it as the sole task of science
to inquire into the connexion and combination of these
elements, which are of the same nature in all departments,
and into their mutual dependence on one another ; we may
then reasonably expect to build a unified monistic structure
upon this conception, and thus to get rid of the distressing
confusions of dualism. Indeed, it is by regarding matter as
something absolutely stable and immutable that we actually
destroy the connexion between physics and physiology.
Epistemological criticism can indeed do no one any
harm, but the specialist, the physicist, for instance, has
no reason to allow himself to be troubled overmuch by
such speculations. Acuteness of observation and a felicitous
instinct are very safe guides fcr him. His conceptions, in
THE ANALYSIS OF SENSATIONS 313
so far as they prove to be inadequate, will be best and most
quickly corrected by the facts. But when it is a question
of bringing into connexion two adjacent departments, each
of which has been developed in its special and peculiar way,
the connexion cannot be effected by means of the limited
conceptions of a narrow special department. By means of
more general considerations, conceptions have to be created
which shall be adequate for the wider domain. Every
physicist is not an epistemologist, nor ought every physicist
to be one, even if it were possible. Special research
demands a man's full energies ; but so does epistemology.
Not long after the first edition of this book was published,
I was lectured by a physicist on the misguided way in which
I had conceived my task. In his opinion, it was impossible
to analyse the sensations as long as the paths of the atoms
in the brain were unknown; and when they were known
everything else would follow of itself. Of course I had not
much use for utterances such as these, which, had I been a
young man of the period of Laplace, might have fallen upon
fertile ground and have developed into a psychological
theory based on " concealed movements." The effect
which they had was, however, to make me offer a silent
apology to Dubois-Reymond with his Ignorabimus^ a
dictum which up to that moment I had regarded as the
greatest mistake. After all, Dubois-Reymond's recognition
of the insolubility of his problem was an immense step in
advance ; this recognition removed a weight from many
men's minds, as is shewn by the success of his work, a
success which is otherwise scarcely intelligible. 1 He did
1 Dubois-Reymond, Ueber die Grenzen des Naturerkennens, 1872,
4th. ed.
314 THE ANALYSIS OF SENSATIONS
not, indeed, take the further important step of seeing that
the recognition of a problem as insoluble in principle, must
depend on a mistaken way of stating the question. For he
too, like countless others, took the instruments of a special
science to be the actual world.
The sciences may be distinguished according to the
matter of which they treat, as also by their manner of treat-
ing it. But all science has for its aim the representation of
facts in thought, either for practical ends, or for removing
intellectual discomfort. Resuming the terminology of
the "Introductory Remarks," science, we may say, arises
when the combination of the other elements is imitated by
the elements a (3 7. . . . For example, physics (in its
broadest signification) arises by the representative repro-
duction of the elements A B C in their relations to one
another; the physiology or psychology of the senses, through
reproducing in like manner the relations of A B C . . . to
K L M . . . ; physiology, through reproducing the relations
of K L M ... to one another and to A B C . . . ; while
the reproducing of the a /5 7 ... themselves by other
a /3 7 . . . leads to the psychological sciences proper.
Now one might be of the opinion, say, with respect to
physics, that the portrayal of the sense-given facts is of less
importance than the atoms, forces, and laws which form, so
to speak, the nucleus of the sense-given facts. But un-
biassed reflexion discloses that every practical and intel-
lectual need is satisfied the moment our thoughts have
acquired the power to represent the facts of the senses
THE ANALYSIS OF SENSATIONS 315
completely. Such representation, consequently, is the end
and aim of physics ; while atoms, forces, and laws are
merely means facilitating the representation. Their value
extends as far, and as far only, as the help they afford.
Our knowledge of a natural phenomenon, say of -an
earthquake, is as complete as possible when our thoughts
so marshal before the eye of the mind all the relevant sense-
given facts of the case that they may be regarded almost as
a substitute for the phenomenon itself, and the facts appear
to us as old familiar figures, having no power to occasion
surprise. When, in imagination, we hear the subterranean
thunders, feel the oscillation of the earth, figure to ourselves
the sensation produced by the rising and sinking of the
ground, the cracking of the walls, the falling of the plaster,
the movement of the furniture and the pictures, the stopping
of the clocks, the rattling and smashing of windows, the
wrenching of the door-posts, the jamming of the doors;
when we see in mind the oncoming undulation passing over
a forest as lightly as a gust of wind over a field of grain,
breaking the branches of the trees ; when we see the town
enveloped in a cloud of dust, hear the bells begin to ring
in the towers ; further, when the subterranean processes,
which are at present unknown to us, shall stand out in full
sensational reality before our eyes, so that we shall see the
earthquake advancing as we see a waggon approaching in
the distance till finally we hear the earth shaking beneath
our feet, then more insight than this we cannot have, and
more we do not require. If we cannot combine the partial
316 THE ANALYSIS OF SENSATIONS
facts in their right proportions without the aid of certain
auxiliary mathematical conceptions or geometrical construc-
tions, it yet remains true that these constructions merely
enable our thoughts to grasp gradually and piecemeal what
they are unable to grasp all at once. But these auxiliary
conceptions would be devoid of value, could we not reach,
by their help, the graphic representation of the sense-given
facts.
When I see in thought a white beam of light which falls
upon a prism issue forth in a fan-shaped band of colors
having certain angles which I can specify beforehand ; when
1 see the real spectrum-image, obtained upon a screen by
interposing a lens, with Fraunhofer's lines occurring in it at
points determinable in advance ; when I see, in my mind,
how these lines alter their position on the prism being
turned, on its substance being changed, or on the ther-
mometer in contact with it altering its register, then I know
all that I can require. All auxiliary conceptions, laws, and
formulae, are but quantitative norms, regulating my sensory
representation of the facts. The latter is the end, the
former are the means.
The adaptation of thoughts to facts, accordingly, is the
aim of all scientific research. In this, science only deliber-
ately and consciously pursues what in daily life goes on
unnoticed and of its own accord. As soon as we become
capable of self-observation, we find our thoughts, in large
measure, already adjusted to the facts. Our thoughts
marshal the elements before us in groups copying the order
of the sense-given facts. But the limited supply of thoughts
THE ANALYSIS OF SENSATIONS 317
cannot keep pace with the constantly augmenting sweep of
experience. Almost every new fact necessitates a new
adaptation, which finds its ｅxpression in the operation of
judgment.
This process is easily followed in children. A child, on
its first visit from the town to the country, strays, for
instance, into a large meadow, looks about, and says
wonderingly : "We are in a ball. The world is a blue
ball." l Here we have two judgments. What is the process
accompanying their formation? In the first instance, the
already existing sensational representation "we" (himself
and his companions) is filled out into a single image by
means of the representation of a ball, which also already
existed. Similarly, in the second judgment, the image of
the " world " (/.*., all the objects of the environment) is
supplemented by combination with the image of an envelop
ing blue ball (the representation of which must also have
been present, since otherwise the name for it would have
been wanting). A judgment is thus always a supplement-
ing of a sensational presentation in order to represent more
completely a sensational fact. If the judgment can be
expressed in words, then the new presentation is never
more than a combination of formerly established memory-
images, which can also be elicited in a person addressed
by words.
The process of judgment, therefore, in the present case,
consists in the enrichment, extension, and supplementation
1 This example is not fictitious, but was observed in the case of my
three-year-old child. In this case what is actually attested is a physio-
logical fact, but this has only been recognized at a late stage. Scientific
astronomy begins in antiquity with similar naif assertions, which it
thinks are physical.
3i8 THE ANALYSIS OF SENSATIONS
of sensational presentations by other sensational presenta-
tions under the guidance of sense-given facts. If the pro-
cess is over, and the image has assumed a familiar shape,
making its appearance in consciousness as a completed
presentation, then we have no longer to do with a judgment
but merely with a simple memory. 1 It is to the formation
of such intuitive knowledge, as Locke calls it, that natural
science and mathematics mainly owe their growth. Con-
sider, for example, the following statements : (i) the tree
has a root ; (2) the frog has no claws ; (3) the caterpillar is
transformed into a butterfly ; (4) weak sulphuric acid dis-
solves zinc ; (5) friction electrifies glass ; (6) an electric
current deflects a magnetic needle ; (?) a cube has six
surfaces, eight corners, twelve edges. The first statement
contains a spatial extension of the presentation " tree " ;
the second a correction of a presentation too hastily
generalized from habit ; the third, fourth, fifth, and sixth
contain temporal extensions of their respective presentations.
1 I cannot here enter upon an examination of the process of judgment
as such. But among recent works on the subject I should like to draw
special attention to W. Jerusalem's Die Urteilsfiinktion (Vienna, 1895).
Though my own position is not that of the author's, I nevertheless have
been greatly stimulated and instructed by many of the investigations of
special points contained in his book. The physiological aspects, and
in particular the biological function of judgment, are set forth in a very
lively way. His conception of the subject in judgment as a centre of
force can scarcely be called felicitous. on the other hand, it will
certainly be readily admitted that in the early stages of culture and of
the formation of language anthropomorphic conceptions exerted much
influence. Other questions of a different kind are discussed by A.
Stohrin 7heorieder Namen (1889), Die Vieldeutigkeit des (7rtet/s(i&9$),
and Algebra der Grammatik (1898). Of these works, those concerned
with the relation between logic and grammar seem to me the most
interesting.
THE ANALYSIS OF SENSATIONS 319
The seventh proposition is an example of geometrical
intuitive knowledge.
6.
Intuitive knowledge of the sort just described impresses
itself upon the memory, and makes its appearance in the
form of recollections which spontaneously supplement every
fact presented by the senses. The various facts are not
exactly alike. But the component parts of the sensational
presentation which are common to different cases are
emphasized, and so we reach a principle which holds a
paramount place in memory the principle of broadest
possible generalization or continuity. on the other hand, if
memory is to do justice to the complexity of facts, and be
of real practical use, it must conform to the principle of
sufficient differentiation. Even the animal is reminded, by
soft, bright red and yellow fruits (seen without exertion on
the tree), of their sweet taste, and by green hard fruits
(which are seen with difficulty), of their sour taste. The
insect-hunting monkey snatches at everything that buzzes
and flies, but avoids the yellow and black fly, the wasp.
Here we have expressed, distinctly enough, the combined
effort for the greatest possible generalization and continuity
and lot practically sufficient differentiation of memory. And
both ends are attained by the same means, the selection and
emphasis of those particular elements of the sensational pre-
sentations which are determinative of the direction which
the thought must pursue to suit the experience. The
physicist proceeds in quite an analogous manner, when he
says (generalizing) : All transparent solids refract incident
light towards the perpendicular, and when he adds (differ-
320 THE ANALYSIS OF SENSATIONS
entiating) : amorphous bodies and isomeric crystals simply,
the rest doubly.
A great part of our mental adaptation takes place un-
consciously and involuntarily, under the guidance of the
facts presented to the senses. If this adaptation has
become sufficiently comprehensive to embrace the vast
majority of the occurring facts, and subsequently we come
upon a fact which runs violently counter to the customary
course of our thought without our being able to discover at
once the determinative factor likely to lead to a new differ-
entiation, then a problem arises. The new, unusual, and
marvellous acts as a stimulus, which irresistibly attracts the
attention. Practical considerations, or even bare intellectual
discomfort, may engender the will to remove the contradic-
tion or to adapt our thoughts to the new fact. Thus arises
purposive thought-adaptation, or investigation.
For example, we have all, at some time or another, quite
contrary to the common run of our experience, observed a
lever or pulley lifting a large weight by means of a small
one. We seek the differentiating factor, which cannot be
immediately disclosed to us by the fact itself as given to
the senses. It is only when, comparing various similar
facts, we have noted the influence of the weights, and of
the arms of the lever, and by our own exertions have reached
the abstract concepts of "moment" or "work," that the
problem is solved. " Moment " or " work " is the differen-
tiating element. When it has become a habit of thought to
pay attention to "moment" or "work," the problem no
longer exists.
THE ANALYSIS OF SENSATIONS 321
8.
What do we do when we abstract ? What is an abstrac-
tion ? What is a concept ? Is there a sensational presentation-
image corresponding to the concept ? I cannot represent
to myself a man in general. I can at most represent to
myself a particular man, or perhaps one combining such
accidental peculiarities of different men as are not exclusive
of each other. A universal triangle, which is at once right-
angled and equilateral, cannot be imagined. Further, the
image thus rising into consciousness at the name of the con-
cept, and accompanying the conceptual process, is not the
concept. In fact, generally, words, being designations which
from necessity must be used to describe many particular
presentations, are far from corresponding completely to any
concept. A child who has seen for the first time a black
dog and heard it named, soon afterward calls a large and
swiftly-running black beetle, "dog"; or a pig or a sheep,
"dog." 1 Any similarity whatever reminding him of the
presentation to which the name was first given naturally
leads to the use of the same name. The point of similarity
need not be at all the same in the successive cases. It may
reside, for instance, at one time, in the color, at another
in the motion, at another in the form, at another in the
external covering ; and so on. Thus there is no question
of a concept. Thus a child calls the feathers of a bird
"hairs"; the horns of a cow " feelers ;; ; a shaving-brush,
1 Thus the Marcomanni called the lions sent across the Danube by
the Romans "dogs," and the lonians called the xd-pfa 1 f tne Nile
"crocodiles " from their likeness to the lizards (KpoK65ei\oi) which, in
Ionia, live in the walls. (Herodotos, II., 69.)
X
322 THE ANALYSIS OF SENSATIONS
its father's beard, and the down of a dandelion, without dis-
tinction, "shaving-brush"; and so on. 1 Most adults treat
words in the same manner, only less noticeably so, because
they have a larger vocabulary at their disposal. The illiterate
man calls a rectangle a " square " ; occasionally he also calls
a cube a " square," because of its rectangular boundaries.
The science of language, and a number of authenticated
historical examples, shew that even nations do not act
differently. 2
A concept is never simply a completed presentation.
In using a word denoting a concept, there is nothing in-
volved in the word but a simple impulse to perform some
familiar sensory operation, as the result of which a definite
sensational element (the mark of the concept) is obtained.
For example, when I think of the concept "heptagon," I
enumerate the angles of a figure visibly before me or of
its image in my consciousness; and when in so doing I
reach seven, in which case the sound, the numeral, or my
finger may announce the sensational mark of the number,
then by this very act the given presentation falls under
the given concept. In speaking of a "square number,"
I seek to resolve the number given into components
typified by the operation 5x5, 6x6, etc., the sensational
characteristic of which, namely, the equality of the two
factors multiplied, is patent. The same holds good of
every concept. The activity excited by the word may be
made up of a number of operations, one of which may
contain the other. But the result is always a sensational
element which was not present before.
1 All these examples are taken from actual experience.
2 See W. D. Whitney, Life and Growth of Language, 1875.
THE ANALYSIS OF SENSATIONS 323
In looking at or in imagining a heptagon, the fact of
its having seven angles need not be present to my mind.
This fact is distinctly cognized only on counting. Fre-
quently, the new sensational element may be so obvious
(as it is, for instance, in the case of the triangle) that the
operation of counting seems unnecessary. Such cases,
however, are exceptional, and constitute the main source
of misunderstandings concerning the nature of concepts.
In the case of conic sections (the ellipse, parabola,
hyperbola) I do not directly see that these curves all
fall under the same concept ; but I can discover the fact
by cutting a cone, and by constructing the equation for
conies.
When, therefore, we apply abstract concepts to a fact,
the fact merely acts upon us as an impulse to a sensa-
tional activity, which introduces new sensational elements,
which in their turn may determine the subsequent course
of our thought in harmony with the fact. By this
activity we enrich and extend the fact, which before
was too meagre for us. We do what the chemist does
with his colorless solution of salts, when by a definite
operation he elicits from it a yellow or brown precipi-
tate, which has the power to differentiate the course of
his thought. The concept of the physicist is a definite
reaction-activity, which enriches a fact with new^sensational
elements.
A small measure of sensational endowment and a very
low degree of mobility are sufficient for the formation of
concepts, as is shewn by the history of the mental develop-
ment of the blind, deaf and dumb Laura Bridgman, which
has been made generally accessible by Jerusalem's interest-
324 THE ANALYSIS OF SENSATIONS
ing little book. 1 In Laura Bridgman the sense of smell
wa*s almost entirely lacking ; her only channel for the per-
ception of disturbances and sound-vibrations was the soles
of her feet and her finger-tips her skin, in short; yet
she succeeded in forming simple concepts. By walking
about and by moving her hands she discovers the tactual
signs (the class-characteristics) of a door, a chair, a knife,
and so forth. The power of abstraction does not, indeed,
go very far. The most abstract concepts to which she
was able to attain seem to have been the numbers. on
the whole her mental processes remained, naturally enough,
attached to specific presentations. Evidence of this is
afforded by her taking the sums in a school-book to be
specially intended for her (op. tit., p. 25), and her idea
that heaven, or the world beyond, was a school (op. tit.,
P- 3)-
To revert to an earlier example, when we see a lever,
we are impelled to measure the length of its arms, to weigh
its weights, and to multiply the numbers representing the
lengths of its arms by the numbers representing the values
of its weights. If the same sensational numerical symbol
corresponds to both products, we expect equilibrium. We
have thus gained a new sensational element which was
not antecedently given in the bare fact itself, but which
now differentiates the course of our thought. If we will
keep well in mind the fact that conceptual thought is a re-
1 W. Jerusalem, Laura Bridgman, Vienna, Pichler, 1891. Cp.
also L. W. Stern, Helen Keller, Berlin, 1905; Jerusalem, "Marie
Heurtin," Oesterreichische ftundsckau, Vol. III., pp. 292, 426 (1905).
THE ANALYSIS OF SENSATIONS 325
action-activity which must be thoroughly practised, we shall
understand the well-known fact that no one can familiarize
himself with mathematics or physics or with any natural
science by mere reading without practical exercise. Under-
standing here depends entirely on action. In fact, it is
impossible in any province to grasp the higher abstractions
without a practical working knowledge of its details.
Facts, then, are extended and enriched, and ultimately
again simplified, by conceptual handling. For when the
new determinative sensational element is found (say, the
number representing the virtual moments of the lever),
then the attention is directed to this alone, and the most
diverse groups of facts are found to resemble and not to
resemble each other solely in virtue of this element. Thus
here also, as in the case of intuitive knowledge, everything
is reducible to the discovery, selection, and emphasis of
the determinative sensational elements. Investigation here
only reaches by a roundabout way what is immediately
presented to intuitive cognition.
The chemist with his re-agents, the physicist with his mea-
suring-rod, scales, and galvanometer, and the mathematician
all treat facts in precisely the same way \ the only difference
being that the latter needs to go least outside the elements
a j8 7 . . . KL M in his extension of facts. The aids of
the mathematician are always conveniently at hand. The
investigator and all his thought are a fragment only of
nature, like everything else. There is no real chasm between
him and*he t/other fragments. All elements are equivalent.
on the preceding theory, the essence of abstraction is
not exhausted by terming it (with Kant) negative attention.
It is true that, in abstracting, the attention is turned away
326 THE ANALYSIS OF SENSATIONS
from many sensational elements, but on the other hand, it
is turned towards other new sensational elements ; and
precisely this latter fact is the essential feature. Every
abstraction is founded on the prominence given to certain
sensational elements.
10.
In the foregoing exposition of my views I have left what
I wrote in 1886 unaltered; but at the same time I should
like to refer the reader to the further explanations contained
in a later work of mine. 1 In the second edition of the
Prinzipien der Wdrmekhre (1900), I have also mentioned
the works of H. Gomperz and Ribot, which have appeared
since 1897 ; these works contain investigations which in
many respects have a certain affinity to my own. Both
Gomperz and Ribot exclude scientific concepts from the
scope of their inquiry, and treat only of such vulgar con-
cepts as have been fixed in the words of the common
speech of everyday intercourse. I, on the contrary, am of
the opinion that the nature of concepts is necessarily much
more clearly displayed in scientific concepts, which have
been consciously formed and applied, than in vulgar
concepts. The latter are so vague that they can scarcely
be reckoned as proper concepts at all. The words of
ordinary speech are simply familiar signs which occasion
equally familiar habits of thought. The conceptual content
of such words, in so far as it has any definite form at all,
is scarcely present to consciousness, as Ribot also found
by his statistical experiments. I have no doubt that, if
1 Prinzipien der WtLrmekhre> 1896 ; 2nd ed., 1900, pp. 415, 422.
THE ANALYSIS OF SENSATIONS 327
Ribot and Gomperz had framed their inquiry so as to
include scientific concepts also, my agreement with them
would be even more far-reaching than it actually is.
We have chosen statical moment as a simple example of
a concept. Complicated concepts will require a complicated
system of reactions, drawing upon more or less large parts
of the central nervous system, and helping to create a
correspondingly complicated system of sensational elements
characterizing the concept. Probably the difficulties pointed
out by J. von Kries are not insuperable on this theory. 1
(Cf. pp. 69, 70 above.)
ii.
The facts given by the senses, therefore, are alike the
starting-point and the goal of all the mental adaptations of
the physicist. The thoughts which follow the sense-given
fact immediately are the most familiar, the strongest, and
the most intuitive. Where we cannot at once follow a new
fact, the strongest and most familiar thoughts press forward
to mould it into a richer and more definite shape. This
process is the source of all the hypotheses and speculations
of science, which all find their justification in the mental
adaptation that develops them and ultimately gives them
birth. Thus we think of the planets as projectiles, we figure
to ourselves an electric body as covered with a fluid that
acts at a distance, we think of heat as a substance that passes
from one body to another, until finally the new facts become
as familiar and as intuitive as the older ones, which we have
used as mental helps. Even where immediate intuition is
*J. von Kries, Die materiellen Gmndlagen der Bewusstseinser-
scheinungeti) Freiburg im Breisgau, 1898.
328 THE ANALYSIS OF SENSATIONS
out of the question, the thoughts of the physicist, by care-
fully observing the principle of continuity and of sufficient
differentiation, become ordered in an economically assorted
system of conceptual reactions, which lead, at least by the
shortest path, to intuitive knowledge. All calculations,
constructions, etc., are merely intermediate means, pro-
ceeding step by step, and always using sense-perception as
a support, to the attainment of this kind of intuition in
cases where it cannot be attained immediately.
12.
Let us now consider the results of mental adaptation.
Thoughts can adapt themselves only to what is constant
in the facts ; it is only the mental reconstruction of constant
elements that can yield advantage in point of economy.
Herein is contained the ultimate ground of our effort for
continuity in thought, that is, for the preservation of the
greatest possible constancy, and in this way, too, the results
of the adaptation are rendered intelligible. 1 Continuity,
economy, and constancy mutually condition one another
they are really only different aspects of one and the same
property of all sound thinking.
The unconditionally constant we term substance. I see
a body upon turning my eyes in its direction. I can see
it without touching it, I can touch it without seeing it.
Although the actual appearance of the component elements
1 Cp. my The Science of Mechanics, translated by T. J. M'Cormack,
Chicago, Open Court Publishing Co., 1893, P- 5 O 4-
THE ANALYSIS OF SENSATIONS 329
of the complex is determined in this way by certain conditions,
I yet have these conditions too absolutely in my power to
appreciate or notice them markedly. I regard the body, or
the complex of elements, or the nucleus of this complex,
as always present, whether, for the moment, it is the object
of my senses or not. Having always ready the thought of
this complex, or, symbolically, the thought of its nucleus,
I gain the advantage of being able to predict, and avoid
the disadvantage of being surprised. My behaviour is the
same with regard to the chemical elements, which also
appear to me unconditionally constant. Although here my
mere willing it is not sufficient to make of the complexes in
question sensational facts, and although in the present case
external aids (for instance, bodies exterior to my own body)
also are necessary, I yet leave these aids out of account
as soon as they have become familiar to me, and look upon
the chemical elements as simply constant. The man who
believes in atoms treats them in an analogous way.
In the same manner as with the complex of elements
corresponding to a body, we may also proceed, on a higher
plane of thought-adaptation, with entire provinces of facts.
In speaking of electricity, magnetism, light, and heat, even
when not associating special substances with these names,
we yet ascribe constancy to these provinces of facts, leaving
entirely out of account the familiar conditions under which
they appear ; and we hold the ideas which reproduce them
always in readiness, thereby gaining an advantage similar
to that explained above. When I say a body is "electric,"
far more memories arise in my mind, and my expectations
are associated with far more definite groups of facts, than
if I had emphasized, for instance, the attractions displayed
330 THE ANALYSIS OF SENSATIONS
in the single cases. Yet this hypostasizing may have its
disadvantages, also. In the first place, in proceeding thus,
we always follow the same historical paths. It may be
important, however, to recognize that there is no such
thing as a specific electrical fact, that every such fact can
just as well be regarded, for example, as a chemical one, or
as a thermal one, or rather that all physical facts are made
up, ultimately, of the same sensational elements (colors,
pressures, spaces, times), and that we are merely reminded
by the term " electric " of that particular form in which we
first became acquainted with the fact.
If we have once accustomed ourselves to regard the body,
to and from which we can, at pleasure, turn our glance or
our hand, as constant, then it is easy for us to do the same
in cases in which the conditions of sensational manifesta-
tion lie entirely beyond our power for example, in the
case of the sun and moon, which we cannot touch, or of
parts of the world which we have seen but once and shall
perhaps never see again, or that we know only by descrip-
tion. Such a method of procedure may have high import-
ance for an undisturbed and economical conception of the
world, but it is certainly not the only legitimate method.
It would be merely a consistent additional step, if we were
to regard the whole past, which is, indeed, still present in
its vestiges (since, for instance, we see the stars where they
were thousands of years ago), and the whole future, which
is present in germ (since, for example, our solar system will
be seen where it now is, thousands of years hence), as con
stant. The entire passage of time, in fact, is dependent
solely on conditions of our sensibility. Were a special
purpose given, even this step might be hazarded
THE ANALYSIS OF SENSATIONS 331
14.
Really unconditioned constancy does not exist, as will
be evident from the preceding considerations. We attain
to the idea of absolute constancy only as we overlook or
underrate conditions, or as we regard them as always given,
or as we deliberately disregard them. There is only one
sort of constancy, which embraces all the cases that occur,
namely, constancy of connexion or of relation. Substance,
again, or matter, is not anything unconditionally constant.
What we call matter is a combination of the elements or
sensations according to certain laws. The sensations con-
nected with the different sense-organs of a particular man
are dependent on one another according to laws, as are
the sensations of different men. It is in this that matter
consists. The older generation, especially the physicists
and chemists, will be alarmed by this proposal not to treat
matter as something absolutely constant, but to take as
constant, instead, a fixed law of connexion among elements
which in themselves seem extremely unstable. Even
younger minds may find this conception difficult ; but the
view is inevitable, though I myself at one time went through
a great struggle in order to arrive at it. We shall have to make
up our minds to some such radical change in the method of
our thought, if we want to escape the alternative of perpetu-
ally recurring helplessness in the face of these questions.
There can be no question of abolishing from ordinary
everyday use the vulgar conception of matter which has
been instinctively developed for this purpose. Moreover,
all our concepts of physical measurement can be maintained,
332 THE ANALYSIS OF SENSATIONS
only receiving such critical elucidation as I have tried to
carry out for mechanics, heat, electricity, etc. Purely
empirical concepts here take the place of metaphysical.
But science suffers no loss when a " matter," which is a
rigid, sterile, constant, unknown Something, is replaced by
a constant law, of which the details are still capable of
further explanation by means of physico-physiological re-
search. In doing this our object is not to create a new
philosophy or metaphysics, but to promote the efforts,
which the positive sciences are at this moment making,
towards mutual accommodation.
*$
The propositions of natural science express only such
constancies of connexion as : " The tadpole turns into a
frog. Chlorate of sodium makes its appearance in the form
of cubes. Rays of light are rectilinear. Bodies fall with an
acceleration of 9*81 (m/sec 2 )." When these constancies are
expressed in concepts, we call them laws. Force (in the
mechanical sense) is likewise merely a constancy of con-
nexion. When I say that a body A exerts a force on a body
B, I mean that B, on coming into contraposition with A, is
immediately affected by a certain acceleration with respect
to A.
The singular illusion, that the substance A is the abso-
lutely constant vehicle of a force which takes effect immedi-
ately on j#'s being contraposed to A t is easily removed. If
we, or more exactly speaking, our sense-organs, be put in
the place of B, here a condition intervenes, which, seeing
that it is possible at any time to fulfil it, is invariably
THE ANALYSIS OF SENSATIONS 333
disregarded, and thus A appears to us absolutely constant.
Similarly, a magnet, which we see as often as we care to
look in its direction, appears to us the constant vehicle of a
magnetic force, which becomes operative only upon being
brought near to a particle of iron, which we cannot, with-
out noticing the fact, disregard as easily as we can ourselves. 1
The phrases, " No matter without force, no force without
matter," which are but abortive attempts to remove a self-
incurred contradiction, become superfluous when we re-
cognize only constancies of connexion.
1 6.
Given a sufficient constancy of environment, there is
developed a corresponding constancy of thought. By virtue
of this constancy our thoughts are spontaneously impelled
to complete the half-observed facts. This impulse towards
completion is not prompted by the individual facts as
observed at the time ; nor is it intentionally created ; but
we find it operative in ourselves entirely without our personal
intervention. It confronts us like a power from without,
yet as a power which continually accompanies and assists
us, as a thing of which we stand in need, in order to
1 To the child everything appears substantial, for the perception of
which only his senses are necessary. The child asks where the shadow,
where the extinguished light goes to. He will not allow the electrical
machine to be turned any great length of time for fear of exhausting
the supply of sparks, etc. A boy of less than a year old wanted, when
his father whistled a tune, to catch the notes from his lips. Even with
older children we find the attempt to snatch at coloured after-images,
etc. only upon noting conditions of a fact that are outside ourselves
does the impression of substantiality disappear. The history of the
theory of heat is very instructive in this connexion.
334 THE ANALYSIS OF SENSATIONS
supplement the facts. Although it is developed by experi-
ence, it contains more than is contained in the single
experience. The impulse in a certain measure enriches the
single fact. Through it the fact is more to us. With this
impulse we have always a larger portion of nature in our
field of vision, than the inexperienced man has with the
single fact alone. For the human being, with his thoughts
and his impulses, is himself merely a piece of nature, which
is added to the single fact. This impulse, however, can lay
no claim to infallibility, and there exists no necessity com-
pelling the facts to correspond to it. Our confidence in it
rests entirely upon the supposition, which has been sub-
stantiated by numerous trials, of the sufficiency of our
mental adaptation, a supposition, however, which must be
prepared to be contradicted at any moment.
Not all our ideas representing facts have the same
constancy. Whenever we have a special interest in the
representation of facts, we endeavour to support and cor-
roborate ideas of lesser constancy by ideas of greater
constancy, or to replace them by the latter. Thus Newton
conceived the planets as projectiles, although Kepler's laws
were already well known, and the tides as attracted by the
moon, although the facts of their movement had long been
ascertained. We do not think that we understand the
suction of a pump, or the flowing of a siphon, until we have
mentally added the pressure of the air as holding the chain
of particles together. Similarly we seek to conceive electrical,
optical, and thermal processes as mechanical processes.
This need of the support of weaker thoughts by stronger
thoughts is also called the need of causality, and is the
moving spring of all scientific explanations. We naturally
THE ANALYSIS OF SENSATIONS 335
prefer, as the foundation of this process, the strongest and
most thoroughly tested thoughts, and these are given us by
our much exercised mechanical functions, which we may
test anew at any moment without many or cumbersome
appliances. Hence the authority of mechanical explanations,
especially those by pressure and impact. A corresponding
and still higher authority attaches to mathematical thoughts,
for in their development we stand in need of no extraneous
means whatever, but, on the contrary, invariably carry most
of the material for experimenting about with us. But if we
are once apprised of this, the need of mechanical explana-
tions is appreciably weakened. 1
I have already often pointed out that a so-called " causal "
explanation, also, is nothing more than the statement or
description of an actual fact or of a connexion between facts,
and I might here simply refer to the detailed discussions
in my Theory of Heat and my Popular Lectures. But, as
people who have not made a special study of physics always
believe that they broaden the basis and increase the
profundity of their thought if they assume a fundamental
difference between a scientific description (for instance, of
the development of an embryo) and a physical explanation,
1 Physical experiences other than mechanical may approach to the
value of mechanical experiences as they become more familiar. In my
opinion Strieker has advanced a correct and important view in bringing
causality into connexion with the will (Studien tiber die Assoziation der
Vorstellungen.) Vienna, 1883). When I was a young lecturer in 1861, 1
myself advocated with great warmth and one-sidedness (in the exposition
of Mill's method of difference) the view subsequently expressed by
Strieker. And the idea has never quite left me (cp., for example, my
Science of Mechanics, English trans., pp. 84, 304, 485.) However, I
am at present of the opinion, as the above discussion shews, that this
question is not so simple, and must be looked at from several sides,
(Cp. Warmelehre, 2nd ed., 1900, p. 432.)
336 THE ANALYSIS OF SENSATIONS
I may perhaps be allowed to add a few more words on the
subject. When we describe the growth of a plant, we
notice that there comes into play such an immense variety
of circumstances varying from one case to another, that it
is only in the broader features at most that our description
can hope to apply universally, while as regards the minuter
details it can only be accurate for the individual case.
This is exactly what happens in physics when the circum-
stances are at all complicated; the only difference being
that the circumstances are generally simpler and better
known. That is why it is easier for us in physics to
separate out the circumstances experimentally, and intel-
lectually too, by means of abstraction. Schematization is
easier. For the astronomers of antiquity, to describe the
motion of the planets was a task analogous to what the
description of a plant's development is for a modern
botanist. The discovery of Kepler's laws depends upon
a fortunate and fairly crude schematization. The more
closely we consider a planet, the more individual does its
movement become, and the less exactly does it follow
Kepler's laws. Speaking strictly, all the planets move
differently, and the same planet moves differently at
different times. Now, when Newton gives a " causal
explanation " of the planetary motions by shewing that one
particle of mass m acquires through another particle m f the
acceleration <p = -^, and that the accelerations deter-
mined in the first particle by different particles are summed
geometrically, he is only pointing out or describing facts,
which, although by a roundabout path, yet have been
reached by observation. Let us consider what the process
THE ANALYSIS OF SENSATIONS 337
is. The circumstances determining the planetary motions
are first of all isolated from one another, that is to say, the
individual particles of mass and their distances from one
another. The relation between two particles of mass is
very simple, and we think that we know all the circum-
stances, mass and distance, that determine this relation.
If we have a description which has been found to be
correct for a few cases, we extend it beyond the limits of
experience and assume it to be universally correct, at the
same time disregarding the possibility of any disturbance
from an unknown and alien cause ; in this, indeed, we may
be mistaken, as we should be, for instance, if gravity were
to turn out to be transferred through a medium and to
require time for its transference. The modification of the
relation is equally simple, as was pointed out, when to two
particles a third is added, and to these a fourth, and so on.
Thus Newton's description is not, in fact, the description of
an individual case ; it is a description in terms of elements.
Newton, in describing the way in which the elements of
mass are related to one another in the elements of time,
indicates to us how we can describe in terms of the elements
any individual case we like, according to his pattern. It is
just the same with all the other cases that theoretical physics
has mastered. But this does not mean that the essence of
the description is changed in any way. What we have to do
with, is a general description in terms of elements. If we may
remain satisfied with a representation of the phenomena by
means of differential equations, a view which I long ago
recommended (Mechanik, 1883, 4 tn e d, I 9 OI > P- 53)) an d
which seems to be coming more and more into favor,
this actually amounts to the recognition that explanation
338 THE ANALYSIS OF SENSATIONS
is nothing more than a description in terms of elements.
Every particular case can then be put together out of spatial
and temporal elements, the relations between which are
described by equations.
It was said above that man himself is a fragment of
nature. Let me illustrate this by an example. For the
chemist a substance may be sufficiently characterized merely
by his sensations. In this case the chemist himself sup-
plies, by inner means, the whole wealth of fact necessary
to the determination of his course of thought. But, in
other cases, recourse to reaction by the help of external
means may be necessary. When an electric current flows
round a magnetic needle situated in its plane, the north
pole of the needle is deflected to my left, if I imagine
myself as Ampere's swimmer in the current. I enrich the
fact (current and needle) which is insufficient in itself to
define the direction of my thought, by introducing myself
into the experiment by an inner reaction. I may likewise
lay my watch in the plane of the circuit, so that the hand
moves in the direction of the current. Then the south
pole falls in front of, the north pole behind the dial. Or
I may make ^of the circuit traversed by the current a sun-
dial (on the plan of which the watch in fact was modelled 1 ),
so arranging it that the shadow follows the current.
In this case the north pole will move towards the
shadowed side of the plane of the current. The two
last-mentioned reactions are outward reactions. The
1 By the direction in which its hands move the watch proclaims its
descent from the sun-dial and its discovery in the northern hemisphere.
THE ANALYSIS OF SENSATIONS 339
two species of reactions could not be made use of indis-
criminately if a chasm existed between myself and the
world. Nature is a single whole. The fact that the two
species of reaction are not known in all cases, and that
frequently the observer appears to be entirely without in-
fluence, proves nothing against the view advanced.
Right and left appear to us to be similar, in contrast to
before and behind, and to above and below. Yet it is
certain that they are only different sensations, overwhelmed
by stronger similar sensations. The space of sensation thus
has three strongly marked and essentially different directions.
From a metrical point of view all directions of geometrical
space are identical. Our immediate sensation represents
symmetrical shapes as equivalent ; but in physical respects
they are by no means equivalent. Physical space also has
three essentially different directions, which are most clearly
manifested in a triclinal medium, in the behaviour of an
electro-magnetic element. The same physical properties
appear also in our own body, which is the reason why our
bodies can be used as reagents in physical problems. If
we had an exact physiological knowledge of an element of
our bodies, we should thereby have laid, in all essentials,
the foundation of our understanding of the physical
universe. (Cp. p. 100.)
[8.
I have repeatedly emphasized the unity of the physical
and the psychical, but it is worth while to consider this
unity once more in one of its special aspects. Our psychical
life, in so far as we mean by that term our presentations,
seems to be perfectly independent of physical processes ;
340 THE ANALYSIS OF SENSATIONS
it seems to be a world in itself, with freer laws of its own,
laws that are of a different order. But it is certain that
this is a mere illusion, caused by the fact that only a very
minute part of the traces of physical processes ever comes
to life in our presentations. The circumstances determining
this fragment are much too complicated to grasp, so that
it is impossible to lay down any precise rule for its occur-
rence. In order to determine what thoughts a physicist,
for instance, will connect with the observation of a particular
optical fact, we should have to know the previous events
of his life, the force of the impressions which they have
left behind them, and the facts of the development of
general and technical culture by which he has been influ-
enced ; and finally we should have to be in a position to
take into account his mental disposition at the moment.
To do all this, it would be necessary to enlist as an auxiliary
the whole of physics, in its widest sense, and at an un-
attainably high stage of development. 1
Let us now consider the other side of the picture. A
physical fact, which we experience for the first time, is
strange to us. If it happened in some quite different way
from that in which it actually happens, it would not thereby
be any more puzzling. The way in which it occurs appears
to us not to be determined by anything, least of all to be
uniquely determined. What it is that invests the way in
which a physical fact occurs with the character of deter-
minateness, can only be understood from our psychical
1 Thus, although my ideal of psychology is that it should be purely
physiological, I should nevertheless think it a great mistake to reject
so-called "introspective" psychology entirely. For self-observation
is not only an important means, but in many cases is the only means
of obtaining information as to fundamental facts.
THE ANALYSIS OF SENSATIONS 341
development. The presentational part of our mental life
is the agent which first draws the fact forth from its isola-
tion, brings it into contact with an abundance of other
facts, and then invests it with determinateness, in virtue of
the necessity for agreement with those other facts and for
he exclusion of contradiction. The science of psychology is
auxiliary to physics. The two mutually support one another,
and it is only when they are united that a complete science is
formed. From our standpoint, the antithesis of subject and
object, in the ordinary sense, does not exist. The question
as to the greater or less degree of precision with which pre-
sentations copy the facts, is, like every other question, a
problem of natural science.
19.
Whenever it happens, in a complexus of elements, that
some of the elements are replaced by others, then a con-
stancy of connexion of one kind becomes a different kind.
In such cases it is desirable to discover a constancy which
survives this change. J. R. Mayer was the first to feel this
need, and satisfied it by enunciating his concept of "force,"
which corresponds to the technical mechanical concept of
"work" (Poncelet), or more exactly to the more general
concept of " energy " (Young). Mayer conceives this force
(or energy) as something absolutely constant (as a store of
something, as a material), thus harking back to the most
stubborn intuitive notions. We perceive, from Mayer's
struggle with ｅxpressions, and with general philosophical
phrases (noticeable in the first and second of his treatises),
that he at first felt instinctively and intuitively the urgent
need of such a concept. But his great achievement was
342 H THE ANALYSIS OF SENSATIONS
accomplished only by his adapting the existing physical
concepts to the requirements of the facts as well as to his
needs. 1
20.
When the adaptation is adequate, the facts are spon-
taneously reproduced by the thoughts, and incompletely
given facts are completed. Physics can act only as a
quantitative norm regulating and giving a more precise
conformation to the spontaneously flowing thoughts,
suitably to practical or scientific needs. When I see a
body thrown horizontally, the intuitive picture of a pro-
jectile in motion may rise before my mind. But the
artilleryman or the physicist requires more. He must know,
for example, that if on applying the measuring-rod M to the
horizontal abscissae of the projectile's path, he can count to
i, 2, 3, 4 . . . ., he must, on applying the measure M' to
the vertical ordinates, also count to i, 4, 9, 16 . . . . in
order to reach a point of the path. The function of physics
consists, therefore, in teaching that a fact which, on a
definite reaction R yields a sensory mark JE, also yields, on
the giving of a different reaction J?', a second sensory mark
E '. By this means it is possible to supply more exactly
the deficiencies of incompletely given facts.
The introduction into physics of the universally compar-
able, or so-called " absolute " measurements, the reduction
of all physical measurements to such units as the centimetre,
the gramme, and the second (length, mass and time), has
one peculiar result. There exists in any case a tendency to
1 Cp. Prinzipien der Warmelehre, 2nd ed., 1900.
THE ANALYSIS OF SENSATIONS 343
regard anything that can be physically grasped and measured,
anything that can be stated in such a way as to become
common property, as "objective" and "real," in contrast to
the subjective sensations ; and the absolute measures appear
to give some support to this opinion, and to supply it with a
psychological, if not with a logical, motive. It looks as if what
we call "sensations" in the familiar sense, were something
quite superfluous in physics. Indeed, if we look closer, the
system of units of measurement can be still further simplified.
For the numerical measurement of mass is given by a ratio
of accelerations, and measurement of time can be reduced
to measurement of angles or lengths of arcs. Consequently
measurement of lengths is the foundation of all measure-
ments. But we do not measure mere space; we require
a material standard of measurement, and with this the
whole system of manifold sensations is brought back
again. It is only intuitional sense-presentations that can
lead to the formulation of the equations of physics, and it is
precisely in such presentations that the interpretation of
these equations consists. Thus, though the equations only
contain spatial numerical measurements, these measure-
ments, also, are merely the ordering principle which tells us
out of what members of the series of sensational elements
we have to construct our picture of the world.
21.
I have elsewhere 1 shewn that quantitative enunciations
are only distinguished from qualitative by the fact that the
former have reference to a continuum of homogeneous
1 See Prinzipien der Wdrmelehre, pp. 438, 459.
344 THE ANALYSIS OF SENSATIONS
cases. on this view, the advantageous employment of
equations for purposes of description would only be possible
within a very limited field. There is, however, some pros-
pect of enlarging this field by successive steps without any
limit. This would be done in the following way. All
possible optical sensations, though they cannot be
measured, can be characterized and catalogued by means
of numbers on psycho-physical methods. Thus any optical
experience can be described by representing, by means of
equations, the values of these numerical characteristics as
dependent on the spatial and temporal co-ordinates, and on
one another. And we shall have to hold that a result the
same in principle can be obtained in the fields of the other
senses also. Thus it is possible to assign a perfectly precise
meaning to the ｅxpression used on p. 45 above.
22.
The ascertainment of the dependence of the elements
A B C on one another, K L M being disregarded, is the task
of natural science, or of physics in its broadest sense. But,
in reality, the A B C's are always also dependent on K L M.
There are always equations of the form f(A B C . . .
KL M t . . .)= O. Now since many different observers
K L M . . . , K' L r M' . . . , K" L" M" . . . are in-
volved, we succeed in eliminating the accidental influence
of the variation of K L M, etc., and we thus obtain only the
element that can be stated as common property, namely the
pure dependence of the A B C's on one another. In this
process the KL M . . ., K f L' M' . . ., are treated like
physical instruments, each with its peculiarities, its special
THE ANALYSIS OF SENSATIONS 345
constants, and so forth, from which the results, as finally in-
dicated, have to be set free. But if it is a question merely
of the temporal connexion of one quantitative reaction with
other quantitative reactions, as in the above dynamical
example, the matter is then still simpler. Everything then
turns on the ascertainment of equality or identity of the
A B C's under like circumstances, that is to say, under like
K L M\ which comes to saying that everything turns
merely on the ascertainment of spatial identities. The
kind of quality of the sensations is now indifferent ; it is
their equality that is alone decisive. And now a single
individual suffices to fix relations of dependence which are
valid for all individuals. Thus from this point onwards we
have obtained a safe basis for the whole field of scientific
research, a fact which inures to the advantage of psycho-
physiology as well.
23-
The space of the geometrician is by no means merely the
system of space-sensations (the senses of sight and touch),
but consists rather of a body of conceptually idealized and
formulated physical experiences, having the space-sensations
as their point of departure. In the very fact of the geome-
trician's regarding his space as being of the same nature
at all points and in all directions, he goes far beyond the
space given to sight and touch, which by no means possesses
this simple property (pp. 1 68, 1 8 1 , sqq.). Without experience
in physics the geometrician would never have reached this
conception. The fundamental propositions of geometry
have, as a fact, been acquired wholly by means of physical
experiences, by the superposition of measures of length
346 THE ANALYSIS OF SENSATIONS
and of angles, by the application of rigid bodies to one
another. Without propositions of congruence, no geometry.
Apart from the fact that spatial images would not be pro-
duced in us without physical experience, we should, even
granting their existence, never be able to apply them to one
another and to test their congruence. When we feel com-
pelled to imagine an isosceles triangle as having equal angles
at its base, our compulsion is due to the remembrance of
powerful past experiences. If the proposition had its
source in "pure intuition," there would be no necessity for
learning it. That discoveries may be made by sheer power
of geometrical imagination, and are so made daily, merely
proves that the memory of a given experience can reveal to
the mind features which in the original observation escaped
unnoticed ; just as in the after-image of a bright lamp, new
and previously unseen details may be discovered. Even the
theory of numbers must be looked at in some such manner ;
its fundamental propositions can hardly be viewed as en-
tirely independent of physical experience.
The cogency of geometry (and of all mathematics) is due, not
to the fact that its theories are arrived at by some peculiar kind
of knowledge, but only to the fact that its empirical material,
which is particularly convenient and handy, has been put to
the test very often, and can be put to the test again at any
moment. Moreover, the province of space-experience is far
more limited than that of the whole of experience. The con-
viction of having in all essentials exhausted this limited pro-
vince soon arises and produces the necessary self-confidence. 1
1 Cp- Wdrmelehre, p. 455 ; Meinong, Hume-Studien, Vienna, 1877 ;
Zindler, Beitr&ge ztir Theorie der mathematischen Erkenntnis y
Vienna, 1889.
THE ANALYSIS OF SENSATIONS 347
24.
A self-confidence similar to that of the geometrician is
doubtless also possessed by the composer and the decora-
tive painter, who have both gained, the former in the
domain of sensations of tone, the latter in that of sensations
of color, a broad and rich experience. To the one no
space-figure will occur the elements of which are not well
known to him, and the two others will meet with no new
combinations of tone or of color that are unfamiliar to
them. But the inexperienced beginner in geometry will be
no less surprised and disappointed by the results of his
activity than the young musician or decorator.
The mathematician, the composer, the decorator, and
the student of natural science, when indulging in specula-
tion, pursue quite analogous modes of procedure, despite
the differences of their materials and aims. The mathe-
matician, it is true, owing to his more limited material, has
the advantage of the others as regards the certainty of his
procedure ; while the latter for the opposite reason is at a
disadvantage as compared with the others.
25-
The distinction between physiological and geometrical
space has proved to be unavoidable. But while geome-
trical insight is obtained by the spatial comparison of bodies
with one another, time also cannot be left out of considera-
tion, since it is impossible, in making such comparisons, to
disregard the translation of bodies. Space and time stand
348 THE ANALYSIS OF SENSATIONS
in intimate connexion, thereby shewing themselves to be
relatively independent of the other physical elements. This
is expressed in the fact that when bodies move their other
properties remain relatively constant. It is precisely owing
to this fact that pure geometry and mechanics are possible.
Space and time, closely considered, stand, as regards
physiology, for special kinds of sensations ; but, as regards
physics, they stand for functional dependencies upon one
another of the elements characterized by the sensations.
When the spatial and temporal physiological indices,
conditioned by the parts and processes of our body, are
compared with one another in like physiological circum-
stances, we obtain relations of dependence of the physical
elements on one another, that is, dependence of the
elements of one body on those of another, and dependence
of the elements of one process on those of another. on the
basis of this result we can take the temporal and spatial
determinations in a purely physical sense. Whatever
coincides with the smaller part of a process which takes
place continuously in one direction, is earlier in time. In
a homogeneously filled space the position B is nearer than
another position to the position A, when B is reached by
the process starting from A earlier than the other position
is reached. The straight line is the class-concept of the
positions uniquely determined by the physical relations
between two points, or infinitely small bodies. The
position C is situated at the point of bisection of the
straight line AB^ when, in homogeneous space, processes
starting from A and B reach that position in equal times,
and reach it in a shorter time than any other position with
which it shares the first property.
THE ANALYSIS OF SENSATIONS 349
26.
The time of the physicist does not coincide with the
system of time-sensations. When the physicist wishes to
determine a period of time, he applies, as his standards of
measurement, identical processes or processes assumed to
be identical, such as vibrations of a pendulum, the rotations
of the earth, etc. The fact connected with the time-sensa-
tion is in this manner made the subject of a reaction, and
the result of this reaction, the number which is obtained,
serves, in place of the time-sensation, to determine more
exactly the subsequent movement of the thought. In like
manner, we regulate our thoughts concerning thermal pro-
cesses not according to the sensation of warmth which
bodies yield us, but according to the much more definite
sensation which is obtained from thermometrical reactions
by simply noting the height of the mercury. Usually a
space-sensation (a rotation-angle of the earth, or the path
of the hand on the dial of a clock) is substituted for the
sensation of time, and for this, again, a number is put.
For example, if we represent the excess of the temperature of
a cooling body over that of its surroundings by S = T~**,
then t is this number.
The relation in which the quantities of an equation stand,
is usually (analytically) a more general one than that which is
meant to be represented by the equation. Thus in the equa-
tion (x/a) 2 + ( yjb) 2 = i all possible values of x have an analyti-
cal meaning, and yield corresponding values of y. But if the
equation be used to represent an ellipse, then only the values
of x < a and y < b have a geometrical (or real) significance.
350 THE ANALYSIS OF SENSATIONS
Similarly, it would have to be expressly added, if this
were not obvious, that the equation S = ** represents
the real process only for increasing values of t.
If we imagine the natural course of different events, say
the cooling of one body and the free descent of a second,
represented by equations involving time, then time may be
eliminated from these equations, and we may express, for
example, the excess of temperature by means of the space
traversed by the falling body. Thus viewed, the elements
appear simply as dependent on one another. But the
meaning of such an equation would have to be more
exactly denned by adding that only increasing distances of
descent or decreasing temperatures are to be inserted
successively therein.
When we thus think of excess of temperature as deter-
mined by the space traversed by a falling body, the
dependence is not an immediate one. on this point I
agree with Petzoldt. 1 But the dependence is no more
immediate when we assume excess of temperature to be
determined by the angle of rotation of the earth. For no
one will believe that the same temperature- values would
continue to correspond to the same angular values, if the
earth were to alter its velocity of rotation in consequence of
some shock. But it seems to me to follow from such con-
siderations that our postulates are merely provisional, and
depend upon partial ignorance of the decisive part played by
certain independent variables which are inaccessible to us.
It is only in this sense that I would wish the reference which
I once made to a certain absence of determination, to be under-
1 Petzoldt, " Das Gesetz der Eindeutigkeit," Vierteljahrcsschrift fur
TV is sense ha ft lie he Philosophic. Vol. XIX., pp. 146 sqq.
THE ANALYSIS OF SENSATIONS 351
stood. 1 This view, moreover, is perfectly compatible with the
postulation of unique determinations, since such postulates
are always laid down on the assumption of given circumstances,
and with abstraction from unusual and unexpected changes.
This way of looking at the matter is, as it seems to me, in-
evitable, when we reflect that the distinction emphasized by
Petzoldt between simultaneous and successive dependencies,
holds for intuitional presentation, but not for the equations
which are the norms regulating presentation quantitatively.
The equations can only be of one kind, and can only express
simultaneous dependencies. Towards indeterminism in the
ordinary sense, the assumption, for instance, of .freedom
of the will in the sense used by many philosophers and
theologians, I have not the slightest inclination.
Time is not reversible. A warm body set in cool sur-
roundings merely cools, and does not grow warm again.
With larger, or later, time-sensations only smaller decreasing
excesses of temperature are connected. A house in flames
burns down but never builds itself up again. A plant does
not decrease in size and creep into the earth, but grows out
of it, increasing in size. The irreversibility of time reduces
itself to the fact that the alterations in the values of physical
quantities always take place in definite directions. Of the
two analytical possibilities one only is actual. We do not
need to see in this fact a metaphysical problem.
Changes can only be determined by differences. Where
there are no distinctions there is no determination. The
supervening change may increase the distinctions or it may
1 Mach, History and Root of the Principle of the Conservation of
Energy, translated by P. E. B. Jourdain, Chicago, Open Court Publish-
ing Co., 1911.
352 THE ANALYSIS OF SENSATIONS
diminish them. But if the differences had a tendency to
increase, change would go on endlessly and aimlessly.
The only assumption compatible with a general representa-
tion of the universe, or rather with the representation of
our own limited environment, is that of a tendency, on the
whole, to a diminution of differences. But if circumstances
that set up differences did not make themselves felt by
forcing their way into our environment, a time would soon
come when nothing more would happen at all.
Again, we can conclude, with Petzoldt, from our own
existence and from our bodily and spiritual stability, to
the stability and to the uniqueness, as regards determina-
tion and direction, of the processes of nature. For not
only are we ourselves a fragment of nature (p. 338 above),
but it is the presence of these very properties in our en-
vironment that determines our existence and our thought
(see Popular Scientific Lectures, 3rd edition, p. 250). But it
will not do to build too confidently on this foundation, for
organisms are peculiar fragments of nature, of very limited
and moderate stability, which in point of fact are liable to de-
struction, and for the preservation of which a proportionately
moderate amount of stability in the environment is sufficient.
The most convenient course will therefore be to recognize the
limits which are everywhere manifestly set to our knowledge,
and to regard the effort towards unique determination as an
ideal, which, so far as may be, we actualize in our thought.
I do not, of course, regard the statements which I wrote
down at the time of my greatest intellectual ferment (1871),
as secure against all attack, particularly as regards their
form ; nor do I by any means consider that Petzoldt's
objections are dictated by a spirit of captiousness. I hope,
THE ANALYSIS OF SENSATIONS 353
however, that when I deal with the subject again at greater
length, for I have only been able to touch upon it briefly
here, I shall be able to bring about a full understanding,
without at the same time giving up any essential part of
my view. 1
1 My recently published book, Erkenntnis undlrrtum (1905), contains
further discussions of the question. See, in particular, pp. 426-440.
XV.
HOW MY VIEWS HAVE BEEN
RECEIVED.
i.
WHEN the first edition of this book was published,
opinions about it were greatly divided. But in
the great majority of cases, it was points of detail that
found acceptance, in so far as the reception was favorable,
-while the fundamental views which had led to the details
were for the most part rejected. All the public criticism
that I have seen has preserved a tone of moderation, even
when it has been hostile, and, in its outspokenness, has
been extremely instructive to me. 1
There is no mistaking the favorable influence which
the later publications of Richard Avenarius have exercised
on the estimation of my book. It surely gives much food
for thought, when we find a professional philosopher
1 That private judgments had been equally moderate I should not
have believed, even if certain small indiscretions had not given me
evidence to the contrary. A more than contemptuous judgment of a
German colleague was communicated to me by a curiously roundabout
path let us say more or less by way of the Antipodes with the un-
mistakable intention of giving me pain. This object, to be sure, was
not attained. For it would certainly be very unfair if I were to refuse
to others the right, which I exercise often enough myself, of neglecting
work that I consider unprofitable. To be sure, I have never felt it
necessary to insult people whose opinions differ from my own.
354
THE ANALYSIS OF SENSATIONS 355
establishing in an elaborate systematic treatise a position
which, when taken up by a scientist, there has been a
disposition to explain away as the aberration of a dilettante.
To-day Avenarius' pupils, and many younger inquirers who
have drawn near to my position by paths of their own,
are standing at my side as allies. Nevertheless, all the
critics, with few exceptions, including those who reproduce
my fundamental ideas quite correctly and have certainly
understood them, cannot help feeling serious objections to
them. There is nothing surprising in this ; for I make
great demands on the plasticity of my readers. It is one
thing to understand an idea logically, and another to take
it up in a sympathetic spirit. The ordering and simplifying
function of logic can, indeed, only begin when psychical
life is in an advanced stage of development and can
already boast a rich store of instinctive acquisitions. Now
it is scarcely possible to attain to this instinctive pre-logical
nucleus of acquisitions by logical means. It is much more
a question of a process of psychical transformation, which,
as I found in my own case, is difficult enough even in
youth. It would therefore be too much to count on
immediate agreement here. on the contrary, I am satisfied
to be merely allowed a hearing at all, and to be listened to
without prepossessions. I will now, following the impres-
sions I have received from my critics, once more bring out
and illustrate those points of which the reception has been
most strenuously opposed. In doing this, I shall treat the
objections that have been urged as typical objections, with
nothing captious or personal about them, and I shall there-
fore not mention any names.
356 THE ANALYSIS OF SENSATIONS
Unless we subject ourselves to a certain compulsion, we
see the earth as standing still, and the sun and the fixed
stars in motion. This way of looking at the matter is not
merely sufficient for ordinary practical purposes, but is also
the simplest and most advantageous. But the opposite
view has established itself as the more convenient for certain
intellectual purposes. Although both are equally correct
and equally well-adapted to their special purpose, the
second view only succeeded in gaining acceptance after a
severe combat with a power hostile to science, a power
which in this case was in alliance with the instinctive
conceptions of ordinary people. But to ask that the
observer should imagine himself as standing upon the sun
instead of upon the earth, is a mere trifle in comparison
with the demand that he should consider the Ego to be
nothing at all, and should resolve it into a transitory
connexion of changing elements. It is true that on various
sides, the way has long been prepared for this conception. 1
We see such unities as we call " I " produced by generation
and vanishing in death. Unless we indulge ourselves in
the fiction, so fantastic nowadays, that these unities existed
before birth in a latent state, and will similarly continue to
exist after death, we can only suppose that they are just
temporary unities. Psychology and psycho-pathology teach
1 Cp. the standpoint of Hume and Lichtenberg. For thousands of
years past Buddhism has been approaching this conception from the
practical side. Cp. Paul Carus, The, Gospel of Buddha, Chicago, 1894.
Cp. also the wonderful story unfolded by the same writer in Karma, A
Story of Early Buddhism^ Chicago, 1894.
THE ANALYSIS OF SENSATIONS 357
us that the Ego can grow and be enriched, can be
impoverished and shrink, can become alien to itself, and
can split up, in a word, can change in important respects
in the course of its life. In spite of all this, the Ego is
what is most important and most constant for my instinctive
conceptions. It is the bond that holds all my experiences
together, and the source of all my activity. In just the
same way, again, a rigid body is something very constant
for our crude instinctive conceptions. If it is divided,
dissolved, or chemically combined with another body, the
number of these constancies increases and diminishes.
Then, in order to hold fast at any price to the notion that
has become so dear to us, we assume latent constancies,
and take refuge in atomism. Inasmuch as we are often
able to restore again the body which has disappeared or
changed, this procedure rests upon somewhat better
grounds than in the case of the Ego.
Now in practice we can as little do without the Ego-
presentation when we act, as we can do without the
presentation of a body when we grasp at a thing. Physio'
logically we remain egoists and materialists, just as we
always see the sun rise again. But theoretically this way
of looking at the matter cannot be maintained. Let us
change it by way of experiment. If in doing so we obtain
a glimpse of the truth, it will in the long run bear practical
fruits as well.
Anyone who has at some time or another been influenced
by Kant, anyone who has adopted an idealistic standpoint,
and has been unable to get rid of the last traces of the
358 THE ANALYSIS OF SENSATIONS
notion of the "thing in itself," retains a certain inclination
towards solipsism, which will appear more or less clearly.
Having been through it in my early youth, I know this
condition of mind well, and can easily understand it. The
philosophical thinker proceeds to make the single problem
of the Ego, a problem which is in principle insoluble,
the starting-point for everything else. The Ego is some-
thing given to us, we cannot transcend it and get away from
it. When, therefore, speculative philosophers say " Solipsism
is the only logically consistent standpoint," their utterance
is quite intelligible in view of their struggle to reach a
closed, all-inclusive, complete system of the universe. To
be sure, we ought to add that materialism also is equally
consistent for anyone who believes that matter is the only
thing that is immediately given, and that cannot be further
explained. This, indeed, is true of all systems. But when
a man of science tells me that solipsism is the only con-
sistent standpoint, he excites my astonishment. I will not
emphasize the fact that this standpoint is better suited
to a fakir who dreams his life away in contemplation,
than to a serious, thoughtful and active man. But what I
do believe is that the man of science who inclines this way
is making a confusion between philosophical and scientific
methods. The man of science is not looking for a com-
pleted vision of the universe ; he knows beforehand that all
his labor can only go to broaden and deepen his insight.
For him there is no problem of which the solution would
not still require to be carried deeper; but there is also
no problem which he can regard as absolutely insoluble.
If it is impossible for the time being to make any
impression on a problem, he solves in the meanwhile
THE ANALYSIS OF SENSATIONS 359
others that are more accessible. If he then returns to
the original problem, it has generally lost much of its
terrifying appearance.
No doubt the Ego is not exhausted, if we say, quite
provisionally, that it consists in a peculiar connexion of the
elements, as long as the nature of this connexion is not
investigated in detail. But the special problems that are
relevant here will not be solved by speculation j their solu-
tion will be found by the psychologists, physiologists, and
psychiatrists, to whom we already owe many important
elucidations of such problems. The physical substratum
of the Ego, the body, 1 will afford many points of reference
which introspective psychology can only handle in a very im-
perfect manner. A man of science who should be a solipsist
would be like a physicist for whom the thermometer was
the fundamental problem of the universe, because on any
particular day he did not happen to have a perfectly clear
understanding of the influence of temperature on expansion.
on the other hand, the philosopher who is a solipsist seems
to me to be like the man who gave up turning round
because whatever he saw was always in front of him. As
to the instinctive, but untenable, splitting up of the Ego
into an object experienced and an active or observing
subject, a problem which has tormented everybody long
enough, anyone who wishes to think out these questions
may compare pp. 25-29 above.
1 But what is in question here is not a transcendental, unknowable
Ego, which many philosophers perhaps still think it impossible to
eliminate as a last remnant of the thing-in-itself, although, generally
speaking, they have risen superior to that notion by now.
360 THE ANALYSIS OF SENSATIONS
Whoever cannot get rid of the conception of the Ego as
a reality which underlies everything, will also not be able
to avoid drawing a fundamental distinction between my
sensations and your sensations. In the same way, whoever
believes in the absolute constancy of a body, thinks of this
body as the single vehicle of all its properties. But when
this silvery-white piece of sodium is melted, and dissolves
in steam which looks absolutely different from the original
thing ; when the sodium is divided into different parts and
transferred to different chemical combinations, so that
more, or even fewer, bodies are present than before ; then
our habitual manner of thought can only be preserved by
extremely artificial devices. It then becomes more advan-
tageous to regard the particular properties as belonging
sometimes to one and sometimes to another complex, or
body, and to substitute, for the bodies that are not constant,
the law which is constant and which survives the change of
the properties and of their connexions. Here again, it is
making no small demand, to ask that this new habit of
thought should be adopted. How the thinkers of antiquity
would have protested, if someone had said to them, " Earth,
water and air are not constant bodies at all; what are
constant are the modern chemical elements of which they
are composed, many of which elements cannot be seen,
while others can only be isolated or fixed with great diffi-
culty. Fire is not a body at all, but a process," and so on.
We are scarcely able to estimate correctly nowadays the
magnitude of the change which lies in this step. Yet in
THE ANALYSIS OF SENSATIONS 361
modern chemistry a further transformation in this direction
is being prepared, and the same methods of abstraction
lead in due course to the standpoint which is adopted here.
From the standpoint which I here take up for purposes of
general orientation, I no more draw an essential distinction
between my sensations and the sensations of another person,
than I regard red or green as belonging to an individual
body. The same elements are connected at different points
of attachment, namely the Ego's. But these points of
attachment are not anything constant. They arise, they
perish, and are incessantly being modified. But where
there is no connexion at a given moment, there is also no
perceptible reciprocal influence. Whether it may or may not
prove possible to transfer someone else's sensations to me by
means of nervous connexions, my view is not affected one
way or the other. The most familiar facts provide a sufficient
basis for this view.
Perhaps even more than in my fundamental ideas, many
readers have found a stumbling-block in what they took,
erroneously indeed, to be the general character of my
conception of the universe. And, to begin with, I must
say that anyone who, in spite of repeated protests from
myself and from other quarters, identifies my view with
that of Berkeley, is undoubtedly very far removed from a
proper appreciation of my position. 1 This misconception
1 Shall once again state the difference in a word ? Berkeley regards
the ' ' elements " as conditioned by an unknown cause external to
them (God) ; accordingly Kant, in order to appear as a sober realist,
invents the " thing-in-itself " ; whereas, on the view which I advocate,
a dependence of the "elements" on one another is theoretically and
362 THE ANALYSIS OF SENSATIONS
is no doubt partly due to the fact that my view was de-
veloped from an earlier idealistic phase, which has left on
my language traces which are probably not even yet entirely
obliterated. For, of all the approaches to my standpoint,
the one by way of idealism seems to me the easiest and
most natural. And connected with this is the fear of
pan-psychism, which at the same time seizes my readers.
Many are the victims that fall a prey to pan-psychism, in the
desperate struggle between a monistic conception of the uni-
verse and instinctive dualistic prejudices. In my early youth
I had to work through these tendencies myself, and Avenarius
was still labouring at them in his book of 1876. As regards
these two points, I feel it to be a piece of particularly good
fortune that Avenarius has developed the same conception of
the relation between the physical and psychical on an entirely
realistic, or, if the phrase be preferred, a materialistic founda-
tion, so that I need do no more than refer to his discussions.
6.
My world of elements, or sensations, strikes not only men
of science, but also professional philosophers, as too un-
practically all that is required. It seems to me that, in the interpreta-
tion of Kant, his very natural and psychologically intelligible fear of
being considered fantastic, has not been sufficiently taken into account.
It is only from this point of view that we can understand how, while
holding that only those concepts had meaning and value which were
applicable to a possible experience, he could posit a thing in itself, of
which no experience is conceivable. Over against the particular sensation,
the plain man and the man of science both set the thing as a presentational
complex of all the experiences, whether remembered or still expected,
which are connected with the sensation in question ; and this procedure
is extremely shrewd. But for anyone who has assimilated Kant's way
of thinking, it becomes meaningless at the limits of experience.
THE ANALYSIS OF SENSATIONS 363
substantial. When I treat matter as a mental symbol
standing for a relatively stable complex of sensational
elements, this is described as a conception which does not
make enough of the material world. The external world,
it is felt, is not adequately expressed as a sum of sensa-
tions ; in addition to the actual sensations, we ought at
least to bring in Mill's possibilities of sensation. In reply
to this, I must observe that for me also the world is not
a mere sum of sensations. Indeed, I speak expressly of
functional relations of the elements. But this conception
not only makes Mill's "possibilities" superfluous, but re-
places them by something much more solid, namely the
mathematical concept of function. Had I ever dreamt
that a short, precise ｅxpression would be so easily over-
looked, and that a popular exposition on broad lines
would have been more useful, some such exposition as
that which H. Cornelius 1 has so admirably given " on the
concept of objective existence," would have served my
purpose. In any case, even here I should have avoided
the ｅxpression "possibility," and should have substituted
for it the concept of function.
From ｅxpressions used in other quarters, it would appear
that the true explanation of my position is to be sought in
an exaggerated sensationalism, and in a correspondingly
inadequate understanding of the value of abstraction and
conceptual thought. Now, without a fairly well-marked
sensationalism a man of science cannot accomplish much.
But this does not prevent him from forming clear and pre-
cise concepts. on the contrary. The concepts of modern
1 Psychologic als Erfahrungswissenschaft, Leipzig, 1897, p. 99, and
particularly pp. noand in.
364 THE ANALYSIS OF SENSATIONS
physics will stand comparison, in point of precision and
height of abstraction, with those of any other science ;
but they offer at the same time the advantage that they
can always be traced back with ease and certainty to the
sensational elements on which they are built up. For
science the gulf between intuitional presentation and con-
ceptual thought is not so great, and is not unbridgeable.
I may remark in passing that I am far from thinking
meanly of the concepts of physics ; for nearly forty years
I have been occupied with the criticism of them in various
ways, and with greater thoroughness than they have re-
ceived before. And since my results are gradually, after
long resistance, finding acceptance with physicists, it will
perhaps be allowed that this is no cheap and facile agree-
ment. When the physicist, whose training has accustomed
him to having a kilogram weight pressed into his hand
with every definition, gradually expresses himself as
satisfied with definitions which reduce everything to a
functional relation of sensational elements, the philosopher
will surely not want to be even more of a physicist than
the physicist. Naturally, however, there is no room for
the necessary working out of details in this sketch, which
is intended to be merely a programme for the closer
connexion of the exact sciences with one another; for
further information the reader must be referred to my
works on physics. It would, indeed, be highly pre-
sumptuous of me to assume even that all physicists are
acquainted with these works, much more that they are
familiar to people who are not professional physicists ; yet
it is partly want of familiarity with my works which has
made it possible for me to be accused, for instance,
THE ANALYSIS OF SENSATIONS 365
of having entirely overlooked the " spontaneity " and
"autonomy" of thought. Even towards bare sensations
our attitude is not one of mere passivity; for sensations
disengage a biological reaction, of which the natural con-
tinuation is precisely the adaptation of thought to facts.
If this adaptation were immediately and perfectly success-
ful, the process would ipso facto come to an end. But
since different imperfectly adapted thoughts come into
conflict with one another, the biological process continues.
What I have called the adaptation of thoughts to one
another takes place. Now I should really like to know
what process of scientific development, the logical process
included, is not covered by this statement ? Here I may
be permitted to break off for the present these controversial
remarks, in which I have only been forced to repeat what
I have frequently said and have long been saying.
To many readers the universe, as conceived by me,
seems to be a chaos, a hopelessly tangled web of elements,
They feel the want of leading and unifying points of view.
But this depends on a misinterpretation of the task that I
have set myself. All points of view, which are of value
for the special sciences and for the philosophical considera-
tion of the world, remain capable of further application,
and indeed, are^ so applied by me. The apparently
destructive tendency of the work is merely directed against
superfluous, and therefore misleading, additions to our
concepts. Thus I believe that the contrasts between the
psychical and the physical, and between subjective and
366 THE ANALYSIS OF SENSATIONS
objective, have been correctly reduced by me to what
is essential in them, and at the same time have been
purged of traditional and superstitious conceptions. And
this has been done in such a way that scientifically es-
tablished points of view are not altered, and at the same
time, room is made for new points of view. I have no
desire to set up, in the place of the lamentations of
a piously whining " Ignorabimus," an obstinately self-
sufficient attitude of rejection of everything that is worth
knowing and that can be known. For to refuse to attempt
answers to questions that have been recognized as meaning-
less, is in no sense an act of resignation ; in view of the
mass of material that can really be investigated, it is the
only reasonable course open to a man of science. The
physicist who refrains from seeking for the secret of per-
petual motion, need not nowadays regard this as an act of
resignation, any more than the mathematician, who no
longer troubles himself about the squaring of the circle,
or the solution of equations of the fifth degree in closed
algebraical form. So, too, with more general philosophical
questions : the problems are either'solved, or are recognized
as pointless.
" In what exactly does the fallacy, or the bias, of Mach's
philosophical views consist ? " This question, which one of
my critics asks, strikes me as very harmless. For I am
convinced that my exposition is full of defects in more
than one direction. This, indeed, can scarcely be avoided
when a writer's views are undergoing a radical process of
revolution, for even a single head cannot work out such
a process completely to its conclusion. Hence, though I
can feel these faults, I cannot put my finger on them. If
THE ANALYSIS OF SENSATIONS 367
I could, I should be a long way further advanced towards
my goal. But neither have I been able to obtain a clear
view of my faults from the writings of my critics. Let us,
therefore, wait a little longer.
Arguments have been brought against my views, which
have been fully discussed both in this book and in other
writings of mine ; but I do not state this fact with a desire
to reproach anybody. It must be a real torture to have to
read everything that is published, and, what is more, to
have to pass judgment conscientiously and deliberately in
a brief allotted time. I have never discovered in myself
any taste for this important vocation, and consequently I
have only written three reviews, all told, in a period of forty
years. So I do not grudge it to the reviewers, that they
should have saved themselves a certain amount of trouble,
even though it has been partly at my expense. I hope they
will not take it ill on my part, if I do not re-act to every sally
and to every sarcasm which they fancy has hit its mark.
Honigswald, however, has subsequently devoted a book
to my standpoint (Zur Kritik der Machschen Philosophic,
Berlin, 1903). I must admit that he has taken the trouble
to read my books ; nor have I the least objection to make
to a criticism which decides that my position is incom-
patible with Kant's. Not all philosophers will draw the
inference that my position must therefore be untenable.
My relations to Kant have been peculiar. His critical
idealism was, as I recognize with the greatest gratitude,
the starting-point of all my critical thought; but it was
impossible for me to retain my allegiance to it. I very
soon began to gravitate again towards the views of Berkeley,
which are contained, in a more or less latent form, in Kant's
368 THE ANALYSIS OF SENSATIONS
writings. By studying the physiology of the senses, and
by reading Herbart, I then arrived at views akin to those
of Hume, though at that time I was still unacquainted
with Hume himself. To this very day I cannot help
regarding Berkeley and Hume as far more logically con-
sistent thinkers than Kant. It is not the business of a
man of science to criticize or refute a philosopher like
Kant, though it may be observed in passing that it would
no longer be a particularly heroic achievement to shew the
inadequacy of Kant's philosophy as a guide to modern
scientific research. This has long since been effected by
the progress that has been made in all departments, in-
cluding philosophy itself. When Honigswald enunciates a
number of general points of view, and proceeds to elicit
from them a closed philosophical system, he completely
misapprehends the cautiously tentative methods of ap-
proximation employed by science. The constants of the
man of science are not absolutely constant, nor, on the
other hand, do the changes which he investigates correspond
to the limitless flux of Herakleitos. I call biological aims
11 practical," when they are not directed to pure knowledge
as an end in itself. only consider what the position of
the man of science would be, if, before he began to think,
he had to refute all the philosophical systems one by one.
once more, there is no such thing as "the philosophy of
Mach." 1
8. L/
Whether I shall ever succeed in making my fundamental
ideas plausible to the philosophers, I must leave to time to
1 Cf. Erkenntnis und It rtum, 1905, Preface.
THE ANALYSIS OF SENSATIONS 369
decide. I do not attach much importance to this at
present, though I have a deep reverence for the gigantic
intellectual labors of the great philosophers of all ages. But
I have an honest and lively desire for an understanding with
the natural scientists, and I consider that such an under-
standing is attainable. I should like the scientists to
realize that my view eliminates all metaphysical questions
indifferently, whether they be only regarded as insoluble
at the present moment, or whether they be regarded as
meaningless for all time. I should like them, further, to
reflect that everything that we can know about the world is
necessarily expressed in the sensations, which can be set
free from the individual influence of the observer in a
precisely definable manner (p. 344 above). Everything that
we can want to know is given by the solution of a problem
in mathematical form, by the ascertainment of the functional
dependence of the sensational elements on one another.
This knowledge exhausts the knowledge of "reality." The
bridge between physics, in the widest sense, and scientific
psychology, is formed of these very elements, which are
physical and psychical objects according to the kind of
combination that is being investigated.
A 7 SI
Probably a good many physiologists have taken objection
to a point of detail in my position, as to which I should
like to say something more. I have a great value for re-
searches such as those of S. Exner, 1 and I believe that
1 Entwurf zu einer physiologischen Erkldrung der psychischen
Erscheinungen, Vienna, 1894.
370 THE ANALYSIS OF SENSATIONS
many important problems as to psychical phenomena can
be solved merely by the investigation of the nervous con-
nexions of the central organs, 1 and by observation of the
way in which stimuli are arranged in a quantitative scale. 2
Indeed Exner's book itself is evidence of this. But I feel
that the main problems still remain unsolved. For, from
my point of view, I cannot conceive, any more than I could
nearly forty years ago, how the qualitative variety of sensa-
tions can arise from the variation of the connexions and
from mere quantitative differences. Fechner's psycho-
physics, which have had so important an influence, did
not fail to stimulate me exceedingly at the time. Inspired
by Fechner's book, I delivered some very bad lectures on
the subject, the value of my lectures being still further
diminished by the fact that I soon came to see that Fechner's
theory of formulae of measurement was erroneous. In this
connexion, after explaining Helmholtz's " telegraph-wire "
theory of sensation, I said : " But will the electric processes
in the nerves prove to be too simple to explain adequately
the difference of quality in sensations ? Will it be necessary
to thrust the explanation further back into regions that are
still unknown ? What if, after investigating the whole brain,
we find everywhere nothing but electric currents? My
personal opinion is this. The electrical researches that
have been made on the nerves are no doubt of a very
delicate nature, but in one respect they are very rough.
An electric current of given intensity tells us nothing,
except that a definite quantity of living force passes in the
time-unit through a cross-section of the current. By what
1 Entiuurf zu einer physiologischen Erklarwng der psychischen Erschei-
nungen, p. 4, Vienna, 1894. 2 Op. cit.> p. 3.
THE ANALYSIS OF SENSATIONS 371
processes and by what molecular movements that living
force is assisted, we do not know. It is possible that the
most diverse processes underlie one and the same intensity
of current." 1 Even to-day I have not succeeded in getting
rid of this idea, and I cannot refrain from bringing forward
evidence that confirms it in essentially the same form, as
for instance by referring to the presence of an identical
current in different electrolytes. 2 The progress of physio-
logical chemistry, 3 and the experiments that have been made
in the transplantation of different organs, 4 seem to me to-day
to be still more decisively in favor of my view. Rollett 5
has brought into connexion with one another, and discussed
in a very instructive manner, with reference both to his own
work and to that of others, a number of important questions
closely related to the discussions of this book.
1 " Vorlesungen iiber Psychophysik," Zeitschrijt fiir praktische
Heilkunde, pp. 335, 336, Vienna, 1863.
2 See the preface to the preceding English edition of this book,
Chicago, 1897, pp. v, vi.
3 Huppert, Ueber die Erhaltung der Arteigenschaften, Prague, 1896.
4 Ribbert, " Ueber Transplantation von Ovarium, Hoden, und
Mamma," Archivfur Entioicklungsmechanik, 1898, Vol. VII.
5 " Entwicklungslehre und spezifische Energie," Mittcihtngen des
Vereins der Aerzte in Steiermark^ 1902, No. 8.
INDEX
I
INDEX OF SUBJECTS
Abstraction, what is it ? 325
Adaptation, mental, 328, 365
Acceleration, sensation of, 133,
139 sqq.
organ reacting on, 165
Accommodation of the eye,
how effected, 228 sqq.
After-images, 131, 252
Animals, asymmetry in, 113
intelligence of exaggerated,
196
reflex movements in, 171
sqq., 196, 198
measurement of time by, 250
Animism, 97
Anthropomorphism, 97
Ants, 78 n.
Apoplectic stroke, effect of, on
author, 175
Art, symmetry in, 117 sqq.
Association, 100, 174, 235-244,
264
inertia of, 253
Astronomers, personal equation
of, 251
Asymmetry, 112
Attention, 178 sqq.
Atoms, 311
Biology, connexion of, with
physics, 84 sqq.
Blind, the, space-sensations of,
118, 135, 139, 180, 187
Bodies, permanency and
rigidity of, 191
" Body," what is it ? 13, 32,
329, 330
| Cats, experiments on, 159
Causal explanations, meaning
of, 335-338
Causality, 85 sqq.
\ Change, 351
Chick, the, 126, 171, 179, 188
Color-adaptation, 95
Color-sensations, 64-69, 103
sqq.
connexion of, with space-
sensations, 105
" Concealed movements," 313
Concepts, what are they ? 321-
327
physical, 364
Congruence, 346
geometrical and optical, 107
Consciousness, organ of, 257
Conservation of energy, 55 n.
Consonance, 272 sqq.
Consumption, organic, con-
nexion of, with time-
sensation, 256
Continuity, principle of, 57,
319
Crustacea, experiments on, 157
Cyclostat, 149
2 A
373
374
INDEX
D Frog, reflex movements in the,
97, 158, 183, 241
Deaf-mutes, vertigo in, 159 Function, notion of, in physics
sqq. and biology, 93
Doves, experiments on, 158 i mathematical concept of,
Dreams, u, 253-255, 281 363
anachronisms in, 253 Functional relations, 35
Ear, middle, function of, in
hearing, 299 sqq.
Echidna, 164
Economy of thought, 49, 328
Ego, the, apparent permanency
self -inspection of, 20
-- not primary, 23
-- impermanence of, 357
sqq.
Egyptian drawings, 232
Electricity, 93
Elements (sensations), 8 sqq.,
1 3*??., 35
-- dependence of, on one
another, 344
Embryology, experimental, 95
Emotions, 21
influence of, on time-sensa-
tion, 261
Energy, 341
Equilibrium, function of laby-
rinth of the ear in, 162
sqa,
Evolution, bearing of, on
physiology, 71 sqq.
theory of, as scientific
hypothesis, 79
Eye, motor apparatus of, no
sqq.
experiments with the, 128
reflex movements of the,
132 sqq.
Force, 341
Freedom of the will, 351
Galvanotropic reaction, 159
Genius, definition of, 308
I Geometrical space, 120, 168,
181, 345
Geometry, Greek and Indian,
1 20
i Ghosts, fear of, 75
i Guinea-pigs, behaviour of, when
deprived of labyrinths, 161
sqq.
H
Harmony, function of contrast
in, 288
Hawk-moth, 85
; Hearing, Helmholtz' theory of,
266 sqq.
i author's suggested theory of,
291 sqq.
| Ewald's theory of, 301
i Heredity, 72, 77, 308
Heterodromous processes, 68,
253
Homodromous processes, 68
Horopter, Miiller's, 125
i Horses, deficiency of, in sense
of time, 260
Idealism, 357, 362, 367
Illusions, explanation of, 1 1
visual, 202-208, 220-231,
2343 255
auditory, 255
; Images, mental, 200
INDEX
375
Images, mental, how deter-
mined, 201 sqq.
Immortality, 25
Impulses, innate, 239
Innervation, 173-176 sqq.
and the will, 165-167
of muscles of the eye, 169
Insects, retina of, 228
Intellect, definition of, 196
Intervals, musical, 285-287
sensations connected with,
289 sqq.
I ntr ejection, 28, 51 sqq.
Intuitive knowledge, 319, 327,
328
Inversion, optical, 223 sqq.
Judgment, process of, 317 sq.
Labyrinth of the ear, function
of, 154 sqq.
Light, electro-magnetic theory
of, 104
distribution of, on the retina,
217
M
Matter, not immutable, 312
= combination of sen-
sations, 331
Measurement, standards of, 192
absolute, 342
Mechanical systems, 90
Membranes, vibration of, in
fluids, 299 sqq.
Memory, 235-244
Hering's theory of, 72
Memory-images, 172
Memory-traces, analogy of, to
physical traces, 236
Mice, Japanese, deafness in, 160
Millipede, 188
Mole, equilibrium and hearing
in the, 162 sq.
Moment, 320
Motor sensations, 139 sqq., 146,
!73
Mouse, blind, equilibrium and
hearing in, 162
Music, physiological origin of,
263
relation of speech to, 280 sq.
modern development of, 307
Musical tones, Helmholtz'
analysis of, 265 sqq.
N
Nervous system, interaction of
parts of, 241
Numbers, theory of, dependent
on physics, 346
Nystagmus, 158
Optical space, 168
Organisms, peculiar charac-
teristics of, 98 sqq.
plasticity of, 238
Otolithic apparatus, the, 153
sqq.
Painting, 347
Italian, 233
Pompeian, 232
Pan-psychism, 362
Perspectives, optical pheno-
mena connected with, 212
sqq., 220 sqq., 232
Physical and psychical, the,
connexion between, 17, 22
the, view of relation be-
tween, identical in Mach
and Avenarius, 51 sqq.
the, parallelism of, 60
the, dualism of, 141 sqq.
376
INDEX
Physics, bearing of physiology
and psychology on, Bio-
Physics and biology, connexion
between, 84 sqq.
Pigeons, reflex movements in,
73
Planetary motions, the, 336
Pleasure and pain, 21
Plethysmography, 257
Pseudoscopy, 225
Puzzle-pictures, 212
R
Reflex movements in animals, 1
7.3 sqq.
Relative motion, sensations of, :
142 sqq.
Representation, 257
sensations supplemented by, !
199
Resonance-theory of hearing,
269 sqq., 303
Retina, the, 122 sqq.
movement of images on, 144
Retinas, " synergy " of, 123
Rhythm, no symmetry in, 256 \
Rhythms, identity of, 258 sqq. \
Right and left, distinction of, j
ii2, 339
Rotation, phenomena of, 134, !
138 sq., 140 sqq., 149 sqq.,
158
Semicircular canals, the, 149
sqq.
Sensations, direction of, 109
specific, 184
lower limit of, 243
sexual, 263
Sheep, experiments on, 154
Sight-sensations, 195-234
Silk- worms, 76
Similarity, optical and geo-
metrical, 108 sqq., 115
Solipsism, 36, 37, 358, 359
Sound-color, 269
Sounds, analysis of, 262-309
Space, 339
physiological and geometri-
cal properties of, 120
visual and conceptual, 124
optical and geometrical, 168
geometrical, contrasted with
physiological, 181 sqq.
Euclidean, 182
tactual, 1 86
tactual and optical homo-
geneous, 187
analogy of, to tone-sensa-
tion, 278, 282 sqq.
geometrical, 345
and time, functional inter-
dependence of, 348
Sparrow, 74, 171, 196
Species, preservation of, 81
Specific energies, 122 sqq., 275
Specific sense - energies, prin-
ciple of, 165
Subject and object, 341, 365
Substance, what is it ? 328, 333
Sufficient differentiation, prin-
ciple of, 58, 319
Symmetry, 106, 108, in, 114,
H5 sq.
in music, 272 n.
sense of, 170
Teleology, 80, 83-101
Temperature, how determined,
35
" Thing-in-itself," 6, 361 n.
" Thought-experiment," 194
Time, perspectival contraction
of, 258
dependent on our sensibility,
330
physical, 349
irreversibility of, 351
Time-sensation, 244-261
INDEX
377
Tones, fusion of, 274
Tone-sensations, 262-309
Touch, sensations of, 135 sqq.
Tropisms, 241
U
Unity of consciousness, 27-29
Unity of the physical and
psychical, 339
Vertigo, optical, 138
in deaf-mutes, 148 sqq.
Vertigo, galvanic, 159 sqq.
rotatory,* 5 9 sqq.
Vestibular apparatus, the, 154
Vision, binocular, 125
W
Will, the, 23, 100, 171-180
connexion of, with inner-
vations, 129
to move, sensations con-
nected with, 139
connexion of, with music,
262
freedom of, 351
II
INDEX OF NAMES
Abraham, 268 n.
Ach, 158
Allen, Grant, 103 n.
Alexander, 160-163
Aristotle, 84, 87, 136 n.
Aubert, 66
Auerbach, 268 n.
Autenrieth, 85
Avenarius, 27 n., 30 n., 46-56,
261, 354. 362.
Bain, 173
Benndorf, 103 n.
Beer, 197 n., 230
Berg, 263
Berkeley, 48, 135 ., 361, 367
Bernoulli, J., 121
Bethe, 196, 197 n.
Biehl, 154
Boyle, 174
Breuer, 131, 132, 137, 140, 153,
X 54 155. 159, 162, 163, 164
Brewster, 63, 64 n., 174 n
Bridgman, Laura, 323, 324
Brown, Crum, 133, 144, 148
Briicke, 123, 268 n.
Briihl, 268 n.
Buttel-Reepen, 197
Carus, Paul, 356 n.
Chesselden, 136 n.
Comte, 46
Cornelius, H., 48, 363
Cornelius, P., 286
Cossmann, 89 n.
Cyon, 164
D
D'Alembert, 272 n.
Darwin, 49, 71, 74, 76, 79, 81,
104 n., 241,. 263
Delage, 155
Descartes, 118, 122, 197
Diderot, 135 n.
Dove, 123
378
INDEX
Dreyfuss, 161
Driesch, 80, 98
Dubois-Reymond, 313
Du Prel, 255
Dvorak, 251, 252, 268 n.
Emch, 119
Euclid, 168, 181, 190, 191 n.
Euler, 272 n., 273 n., 290, 307
Ewald, 149, 153, 158, 164, 241,
301, 302, 303
Exner, 145, 228 n., 230, 268 n,,
369
Fechner, 61, 81 n., 101 n., 210,
251 n,, 264 n.
Fischer, 265 n.
Forel, 197
Fourier, 269
Fraunhofer, 7, 65 n. t 316
Friesach, 302
Gay-Lussac, 310
Geissler, 252
Goethe, i
Goltz, 74, 197, 241
Gomperz, 326, 327
Govi, 122 n., 149
Graber, 292 n.
Grimaldi, 219
Groth, 67
Gruithuisen, 4 n.
Guldberg, 112, 113
Guye, 148
H
Haddon, 117
Haga, 219 n.
Hammerschlag, 160
Hankel, 120
Harvey, 86
Hauptmann, C., 48, 61 n., 89 n.
Hauptmann, M., 272 n.
Heidenhain, in
Heller, 136 n., 137 n.
Helmholtz, 63, 64 n., 117, 126,
173, 191 n., 263, 265-275,
291, 292, 297, 298, 299 .,
301, 305, 306, 370
Hensen, 88 n., 292 n.
Herakleitos, 368
i Herbart, 368
i Hering, 27 n., 30 n., 50, 65-69,
72, 80 n., 99 n., 100 n., 109,
122 n., 124, 125, 139, 168-
170, 172, 177, 178, 181 n.,
183, 197 n., 225, 277 n.
\ Hermann, 245 n., 269, 270, 271,
303
1 Hero, 87
Herodotos, 321 n.
\ Herzfeld, 67 n.
| Heymans, 61 n., 226, 252 n.
I Hillebrand, 125 n., 177 n. t
221 n.
Hirth, 99 n., 136 n.
Hofler, 55 n., 226
Honigswald, 367
Holtz, 96 n., 131
Hume, 4 n., 46, 356 n., 368
Huppert, 371 n.
James, 21, 129, 144, 148, 159,
163, 168 n., 173, 175 n. t
176, 179, 181 n., 257, 310 .
Jerusalem, 318 n., 323, 324 n.
Jones, 116
K
Kant, 30 n., 194. 325. 357' 3 61
n., 367
Kepler, 86, 334, 336
Kessel, 279 n.
King, 174 n.
Kirchhoff, 49
Kohlrausch, 268 n.
Konig, 269, 270
Kornfeld, 257 n.
Krause, E., 103 n.
Krause, C. F., 20 n.
INDEX
379
Kreidl, 132, 153, 157, 159, 160,
162, 163
Kries, von, 61 n., 69 n., 327
Kiilke, 286
Kiilpe, 61 n., 89 n.
Laplace, 313
Leibniz, 191 n., 273 n.
Leonardo da Vinci, 66, 67, 206,
287
Lichtenberg, 28, 356 n.
Lipps, 131 n., 262 n., 273 n.
Lissajous, 232
Locke, 135 n., 318
Loeb, 86, 98, 113, 137 n , 153,
196, 221, 224, 226, 241,
247 n.
Loewy, 135 n.
Lubbock, 149
Ludwig, 66
M
Magnus, 103 n.
Manacei'ne, 255
Mariotte, 39, 310
Marty, 103 n.
Maxwell, 247 n.
Mayer, A., 64
Mayer, J. R., 341
Meinong, 346 n.
Menger, 98
Meumann, 245 n.
Meyer, 270 .'
Meynert, 261
Mill, 92, 335 n., 363
Moliere, 37, 119
Molyneux, 135 n.
Morgan, 76, 77
Moser, 237
Mosso, 257
Munk, 135 n.
Miiller, 27, 59, 122, 125, 126,
202, 203
Miinsterberg, 168 n., 173, 176,
Mygin
245 n., 252
d, 159
N
Nagel, 132, 153, 155, 165
Newton, 49, 64, 92, 121, 174,
307, 334. 336, 337
Nichols, 245 n.
Nietzsche, 25
Obermayer, von, 219 n.
Oettingen, von, 271, 272, 275,
297
Ohm, 265
Oppel, 144, 273 n.
Ostwald, 99 n., 239 n.
Panum, 123, 126, 217, 229
Pauli, 68, 69, 83 n., 112 n., 253
Petzold, 36 n., 48, 350, 351, 352
Pfaundler, 268 n.
Pfeffer, 94
Plateau, 134, 144, 223
Plato, ii
Polak, 273 n.
Politzer, 299
Pollak, 153, 159
Polle, 103 n.
Poncelet, 341
Popper, 20 n., 30 n.
Poulton, 96 n.
Prentiss, 157
Preyer, 31 n.
Ptolemy, 122
Purkinje, 133, 186, 252
R
Rameau, 265
Reimarus, 85
Reinke, 98
Ribbert, 371 n.
Ribot, 4, 21, 326, 327
Riehl, 31 n., 139
Riemann, 181
Robert, 254
3 8o
Rollett, 73, 371
Roux, 95, 99 n.
INDEX
Sachs, 86
Sandford, 252
Saunderson, 136 n.
Sauveur, 265
Schafer, 153, 158
Schaik, van, 88 n.
Scheffler, 228
Schlodtmann, 126 n.
Schmidt, 6 n.
Schnabel, 135 n.
Schneider, 77
Schopenhauer, i, 82 ., 262
Schultz, 104 n.
Schumann, 245 n.
Schuppe, 6 n., 36 n., 46
Schuster, 71
Scripture, 206, 245 n.
Seebeck, 290
Seeliger, 219 n.
Semon, 72 w.
Smith, Adam, 49
Smith, R., 265
Soret, 117, 118, 122, 136 n.
Spencer, 71, 77
Spinoza, 46
Staudt, von, 200
Steiner, 200
Stern, 324 n.
Steinhauser, 265 .
Stohr, 227, 228, 229, 230, 303,
318 w.
Strauss, 75
Strehl, 1 60
Strieker, 280, 335 n.
Stumpf, 61 n., 126 n., 262 n. t
270 w., 272, 273, 274, 290
n., 293, 298, 299
Suess, 236
Szily, von, 146 n.
Tolstoi, 112
Tschermak, 126 n.
Tylor, 52 n., 56
U
Uexkiill, 197 w.
Vergil, 104 n.
Vierordt, 145
Volkmann, 49
W
Wahle, 31 n.
Wallaschek, 246 n.. 255 n.,
260, 261, 309 w.
Wasmann, 199
Weber, 81 n., 299
Weismann, 24, 72, 73, 77, 78,
308
Wheatstone, 123
Whitney, 322 n.
Wilner/95
Wind, 219 n.
Witasek, 226 w.
Wlassak, 50, 56, 181 n., 261
Wollaston, 65
Wundt, 173
Young, 64, 265, 269, 305, 341
Zell, 96 n., 197
Ziegler, 240 .
Zindler, 346 n.
Zollner, 225, 226
TURNBULL AND SPEARS, PRINTERS, EDINBURGH