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ON
INTELLIGENCE
ON
INTELLIGENCE.
BY
H. TAINE, D.C.L. OXON.
TRANSLATED FROM THE FRENCH BY
T. D. HA YE,
AND REVISED WITH ADDITIONS BY THE AUTHOE.
LONDON :
L. REEVE AND CO., 5, HENRIETTA STREET,
COV'ENT GARDEN.
1871.
LONDON :
SAVILL, EDWARDS AND CO., PRINTEKS, CHANDOS STREET,
COVENT GARDEN.
THE Work an author has most fully meditated ought to
be honoured by the name of the friend whom he has most
respected. I dedicate this book to the Memory of FRANZ
WOEPKE, Orientalist and Mathematician, who died at Paris
in March, 1864.
H. TAINE.
PKEFACE.
IF I am not mistaken, we mean now-a-days by Intelligence,
what was formerly called Understanding or Intellect that
is to say, the faculty of knowing ; this, at least, is the sense
in which I have taken the word.
At all events, I here intend to examine our knowledge,
that is to say, our cognitions, and nothing else. The words
faculty, capacity, power, which have played so great a part
in psychology, are only, as we shall see, convenient names by
means of which we put together, in distinct compartments,
all facts of a distinct kind ; these names indicate a character
common to all the facts under a distinct heading ; they do
not indicate a mysterious and profound essence, remaining
constant and hidden under the flow of transient facts. This
is why I have treated of cognitions only, and, if I have
mentioned faculties, it has been to show that in themselves,
and as distinct entities, they do not exist.
Such a precaution as this is very necessary. By means
of it, psychology becomes a science of facts ; for our cogni-
tions are facts ; we can speak with precision and detail of
a sensation, of an idea, of a recollection, of a prevision, as
well as of a vibration, or other physical movement ; in the
one case as in the other there is a fact in question ; it may
be reproduced, observed, described ; it has its precedents,
its accompaniments, its consequents. In little, well-se-
lected, important, significant facts, stated with full details
and minutely noted, we find at present the materials of
every science ; each of them is an instructive specimen, the
head of a rank, a salient example, a clear type to which a
whole row of analogous cases conform ; our main business
is to know its elements, how they arise, in what manner
b
x PREFACE.
and under what conditions they combine, and what are the
constant effects of combinations so produced.
Such is the method it has been attempted to follow in
this work. In the first part, the elements of knowledge
have been determined ; by consecutive reductions we have
arrived at the most simple elements, and have passed from
these to the physiological changes which are the condition
of their origin. In the second part, we have first described
the mechanism and general effect of their combination ;
then, applying the law we have discovered, we have ex-
amined the elements, formation, certitude, and range of the
principal kinds of our knowledge, from that of individual
things to that of general things, from the most special
perceptions, previsions, and recollections, up to the most
universal judgments and axioms.
In these inquiries, Consciousness, our principal instru-
ment, is not sufficient in its ordinary state ; it is no more
sufficient in psychological inquiries than the naked eye in
optical inquiries. For its range is not great ; its illusions
are many and invincible; it is necessary continually to
beware of it; to test and correct its evidence, nearly always
to assist it, to present objects to it in a brighter light, to
magnify them and construct for its use a kind of micro-
scope or telescope ; at all events, to arrange the surround-
ings of the object, to give it the necessary relief by
means of contrasts, or to find beside it indications of its
presence, indications plainer than it is, and indirectly point-
ing out its nature.
Here lies the principal difficulty of the analysis. As far
as pure ideas and their relations with names are concerned,
the principal aid has been afforded by names of numbers,
and, in general, by the notations of arithmetic and algebra ;
thus we have brought again into light a great truth guessed
at by Condillac, and which has lain for a century dormant,
buried, and as though lifeless, for want of satisfactory
evidence. As to images, their effacement, their revival,
their antagonist reductives, the necessary magnifying is
found in the singular and extreme cases observed by physio-
PREFACE. xi
legists and medical men, in dreams, in somnambulism and
hypnotism, in illusions and the hallucinations of sickness.
As to sensations, significant instances are found in the
sensations of sight, and especially in those of hearing.
By means of such evidence, and of the recent discoveries
of physicists and physiologists, we have attempted to con-
struct or sketch out the whole theory of elementary
sensations, to advance beyond the ordinary bounds, up
to the limits of the mental world, to indicate the func-
tions of the principal parts of the brain, to conceive the
connexion of molecular nervous changes with thought.
Other abnormal cases, borrowed both from students of
insanity, and from physiologists, have enabled us to ex-
plain the general process of illusion and rectification,
whose successive stages constitute our various kinds of
knowledge. After this, to elucidate our knowledge of
bodies, and of ourselves, valuable indications have been
found in the profound and closely reasoned analyses of
Bain, Herbert Spencer, and Stuart Mill, in the illusions
of persons who have lost limbs, in all the different
illusions of the senses, in the education of the eye in
persons born blind who have recovered their sight by
operations, in the singular alterations which the idea of self
undergoes during sleep, hypnotism, and madness. We have
then been able to enter upon the examination of the ideas
and general propositions which make up the sciences, properly
so called, to profit by Mr. Mill's acute and accurate
inquiries respecting Induction, to establish against Kant and
Mill a new theory of necessary propositions, to study by a
series of examples what is termed the explanatory reason of
a law, and to conclude with general views on science and
nature, while pausing before the metaphysical problem which
is the first and last of all.
Between psychology thus conceived and history as it is now
written the relationship is very close. For history is applied
psychology, psychology applied to more complex cases. The
historian notes and traces the total transformations presented
by a particular human molecule or group of human molecules ;
b 2
xii PREFACE.
and, to explain these transformations, writes the psychology
of the molecule or group; Carlyle has written that of
Cromwell ; Sainte-Beuve that of Port Royal ; Stendhal has
made twenty attempts on that of the Italians ; M. Renan
has given us that of the Semitic race. Every perspicacious
and philosophical historian labours at that of a man, an epoch,
a people, or a race ; the researches of linguists, mythologists,
and ethnographers have no other aim ; the task is invariably
the description of a human mind, or of the characteristics
common to a group of human minds ; and, what historians do
with respect to the past, the great novelists and dramatists
do with the present. For fifteen years I have contributed to
these special and concrete psychologies ; I now attempt general
and abstract psychology. To comprise it exhaustively, there
would be required a theory of the Will in addition to the
theory of the Intelligence ; if I may judge of the work I
do not venture to undertake by that which I have attempted
to accomplish, my strength is not equal to this ; all that I
venture to hope is that the reader will grant me his indul-
gence, in consideration of the difficulty of the task and the
length of the effort.
H. TAINE.
December, 1869.
TABLE OF CONTENTS.
PAET THE FIKST.
THE ELEMENTS OF KNOWLEDGE.
BOOK I.
OF SIGNS.
CHAPTER I.
OF SIGNS IN GENERAL AND OF SUBSTITUTION.
PACK
I. Different examples of signs A sign is a present experience which
suggests to us the idea of a possible experience 1
II. Names are a species of signs Examples Proper names A proper
name is a sensation or image of the eye or ear, which calls up in us
a group of more or less definite images 2
III. Frequently this group is not called up Examples The name then
becomes the substitute of the group 3
IV. Other examples of substitution In arithmetic In algebra Nature
and importance of substitution. . . . 4
CHAPTER II.
OF GENERAL IDEAS AND SIMPLE SUBSTITUTION.
I. Proper and common names Importance of common or general
names They are the first terms of couples The second terms of
such couples are general and abstract characters 7
II. Consequences of this Experience of such second terms is impossible
Reasons of this impossibility Different examples Difference
between the vague image aroused by the name, and the precise
character denoted by the name Difference between the sensible
image and pure idea , g
tiv CONTENTS.
PAGB
III. Actual formation of a general Idea That which is evolved in us,
when we have seen a series of similar objects, is a final tendency
resulting in a metaphor, a sound, or an expressive gesture Con-
temporary instances Early instances A general name is the
residuum of an expressive sound When we conceive a general
quality, there is nothing more in our minds tha,n a tendency to name,
and a name This name is the substitute of an impossible
experience 10
IV. A general Idea is nothing but a name provided with two characters
The first is the property of being called up on the perception of each
individual of a class The second, the property of calling up in us
images of individuals of this class, and of this class only By these
two properties, the general name corresponds exclusively to the
general quality, and becomes its mental representative Utility of
this substitution 13
V. Formation of general names in the case of little children The
faculty of language is founded on the consecutive tendencies which
survive the experiences of similar individual cases, and correspond
to what there is in common to these individuals Examples of this
tendency in children Special meanings given by them to the names
we teach them Originality and variety of their invention Their
tendencies to name finally coincide with ours Acquisition of
language Difference between human and animal intelligence . . 15
VI. Passage from abstract to collective names The name which denoted
a general quality denotes a group of general qualities Examples
The name then becomes the substitute of several other names, and the
mental representative of a group of general qualities These sub-
stitutes are what we term Ideas 20
CHAPTER III.
OF GENERAL IDEAS AND REPEATED SUBSTITUTIONS.
I. Certain General Characters do not produce in us a distinct impression
They are therefore incapable of exciting in us a general tendency
and a name Indirect process by which we arrive at conceiving
them Example in the case of numbers Their mental represen-
tative is a name of number Formation of names of numbers
Series of superimposed substitutions Our idea of a number is that
of a name substituted for another name combined with unity. . . 23
II. Examples in Geometry Our Idea of a Circle is not the sensible
figure we imagine, but a group of combined names, mental represen-
tatives of certain abstract characters Substitution of the formula
for the impossible experience We conceive the ideal object by
means of its formula Universal employment of substitution in
mathematics 26
CONTENTS. xv
PAOH
III. Examples in the cases of Infinite Series Time and Space In the
case of an infinite series or quantity, we do not conceive the
totality of its terms, but certain of its terms, and one of their
abstract characters represented in us by a name Substitution of
the formula for the impossible experience We conceive the infinite
series or quantity by means of its formula 28
IV. Summary Our general Ideas are names, substitutes for impossible
experiences Psychological Illusion which consists in distinguishing
the idea from the name Singular effects and general cause of this
illusion It is natural that signs should cease to be observed, and
end by being considered as mere nothings False theories on the
pure spirit The mental representative we term a pure idea is
never more than a name pronounced, understood, or imagined
Names are a class of Images The Laws of Ideas are reduced to
the Laws of Images 31
BOOK II.
OF IMAGES.
CHAPTER I.
OP THE NATURE AND REDUCTION OF IMAGES.
I. An Experience An Image is a spontaneously reviving sensation,
usually less energetic and precise than the sensation proper The
force and precision of the image varies in individuals and according
to its kinds Personal Instances Instances of children accustomed
to calculate mentally Precocious mathematicians Blindfolded
chess-players Painters who can draw portraits or make copies
from memory Schools of Art in which this faculty is cultivated
Other instances of the voluntary revival of visual sensations
Sensations of the other senses have their corresponding images
Images corresponding to auditory sensations Examples .... 35
II. Circumstances increasing the precision and force of the image In
such a case it becomes more and more like the sensation Instances
in which the sensation is recent Instances in which the sensation
is immediately expected Examples of images corresponding to
sensations of hearing, of sight, of smell, of taste, of touch Equal
and similar effects of the image and the corresponding sensation
In these cases, the image is taken, at least momentarily, for the
sensation corresponding to it 41
III. How, in spite of this, it differs from the corresponding sensation
The illusion accompanying it is speedily rectified The image inva-
cv i CONTENTS.
PAGB
riably comprises an illusion of greater or less duration Dugald
Stewart's Law Instance of an American preacher Testimony of
M. Flaubert Instance of an English painter Evidence of a
chess-player Observations of Goethe and of M. Maury Volun-
tary hallucinations Various circumstances under which the image
becomes hallucinatory These extreme cases are evidence as to the
normal state In the normal state, the illusion is at once destroyed
It is destroyed by the presence of an antagonist or reductive . . 43
IV. Cases in which the contradicting sensation is too feeble or is annulled
Hypnagogic Hallucinations Experiments of M. Maury Per-
sonal experience Passage from the simple image to the halluci-
natory image, and from that to the simple image Other cases in
which the contradictory sensation is annulled Wounds in battle
Hallucinations strictly so-called Hallucinations of sight after the
prolonged use of the microscope Partial restoration of the anta-
gonist sensation Pathological instances In such cases, the hallu-
cination is destroyed Story of Nicolai General means of destroying
the hallucination Case in which a sensation calls up an illusion
properly so-called Story of Dr. Lazarus In such cases, the sup-
pression of the exciting sensation destroys the illusion 49
V. Other antagonists Reminiscences and general judgments form, by
their combination, a body of auxiliary reductives Their influence
is more or less prompt and energetic Different examples Cases
in which their influence is not sufficient The antagonistic sensa-
tion, which is the special reductive, is then annulled Examples
in intoxication and illness The patient then concludes the halluci-
nation to be an hallucination Instances in which all reductives
are annulled, or of complete mental alienation Remarkable case
recorded by Dr. Lhomme 63
VI. General views as to the thinking being The mind is a collection of
images, like a polypus General views as to the normal reason-
able wakeful state Mutual equilibrium of various images
Constant repression of the rising hallucination by special reductives
Necessity of sleep Summary as to images Their characters and
relations to sensation The image is the substitute of the sensation 70
CHAPTER II.
LAWS OF THE REVIVAL AND OBLITERATION OF IMAGES.
I. The image of a sensation may rise after a considerable interval
Examples It may then rise without having done so during the
interval Examples Singular, morbid instances of the revival of
images which seemed obliterated Recollection of a language learned
in childhood, and afterwards forgotten Automatic recollection of a
series of sounds heard mechanically Probability that every sensa-
tion we experience preserves an indefinite aptitude for revival . . 75
CONTENTS. xvii
PAGE
II. Different sensations have not all this aptitude for revival in an equal
degree Examples General circumstances augmenting this aptitude
Extreme attention, voluntary or involuntary The persistence of
impressions acquired in infancy is thus explained In what atten-
tion consists Competition between our different images The Law
of Natural Selection is applicable to Mental Events Another cir-
cumstance which augments the aptitude for revival Repetition
Examples Why these two circumstances augment the aptitude for
revival 78
III. Special circumstances calling up, at a particular moment, one image
rather than another Example The reviving image has already,
either by contiguity or by similitude, commenced to revive Why
partial revival excites complete revival 82
IV. Absence of the indicated circumstances Want of attention Want
of repetition Enormous number of sensations which thus lose their
aptitude for revival Cases in which two tendencies neutralize each
other Repetition and variety of experience blunt the image
Origin of general names, and of the vague images accompanying
them The majority of our sensations do not exist in our minds in
the state of express images, but in the state of dull consecutive
tendencies .... 86
V. General views as to the history of images and ideas They are in
perpetual conflict for preponderance Effect of internal laws and
external incidents in determining which preponderate Temporary
obliteration, prolonged or definitive, of a whole group of images
Partial and total paralysis of memory, excited by fatigue, loss of
blood, blows, apoplexy Examples Forgetfulness of names For-
getfulness of spoken names, but not of the meaning of written
names Restoration of lost faculties Appearance of new faculties
Examples Aptitudes and faculties are connected with the organic
state Possibility of two organic states severed from one another,
and recurring periodically in the same individual Case of an
American lady Two lives and two mental states may thus be met
with in the same person Instances In what the moral personality
consists Two moral personalities may succeed one another in the
same individual What forms the continuity of a distinct moral
person is the continuous revival of the same distinct group of
images 90
XVIU
CONTENTS.
BOOK III.
OF SENSATIONS.
CHAPTER I.
OF SENSATIONS OF HEARING AND THEIR ELEMENTS.
PAGB
I. Seduction of ideas to a class of images, and of images to a class of
sensations Enumeration of the principal kinds of sensations
What is meant by the word sensation Distinction between the
property of the external object which excites the sensation, and the
sensation itself Distinction between the crude sensation and the
apparent position attributed to it by consciousness Distinction
between the sensation and the state of the nerves and nervous
centres Special and primitive character of sensation 99
II. Classification of sensations by Gerdy, Mueller, Longet, and Bain
Its practical convenience and scientific inadequacy In what the
classified sensations differ from other facts also classified We
cannot distinguish the elements of sensations Physical and Phy-
siological Science cannot distinguish these elements, but only the
conditions of whole sensations Sensations appear to be irreducible
to other more simple data Psychology seems, with reference to
them, what Chemistry is with reference to simple bodies . . . .101
III. Psychology stands with reference to them as Chemistry did with
reference to Chemical Compounds before the discovery of simple
bodies Analysis of the sensations of sound Various kinds of
sounds They are, in appearance, irreducible to one another The
Wheel of Savart and the Siren of Helmholtz Musical Sound
The continuous sensation is then composed of successive elementary
sensations Instance of very deep sounds We can distinguish in
these the successive elementary sensations Each of them has a
certain duration, and passes from a minimum to a maximum of
intensity Instance of certain musical notes Savart's experiment-
Enormous number of elementary sensations succeeding in a second
to form a whole sensation of acute sound Their number increases
in proportion to the acuteness of the sound In this case the ele-
mentary sensations cease to be distinguishable by consciousness
Appearance which the elementary sensation must therefore assume
t actually assumes this appearance The characters of deep, acute,
high, low, full, drawn-out, firm, vibrating, found in the total sen-
sation, are explained by the arrangement of the elementary sen-
. 106
CONTENTS. xix
PAGE
IV. Continuation of the analysis of sensations of sound Explanation
of the sensation of intensity Explanation of the sensation of tone
Discovery of Helmholtz Explanation of the sensation of noise
Construction of the whole of the total sensations of sound by means
of the elementary sensations of sound Analysis of the elementary
sensation of sound It is composed of a maximum, a minimum, and
an infinite number of intermediate states Ill
CHAPTER II.
SENSATIONS OF SIGHT, OF SMELL, OF TASTE, OF TOUCH, AND THEIR
ELEMENTS.
I. Total sensations of sight The spectrum Infinite number of total
sensations of colour There are at least three elementary sensations
of colour It is sufficient to admit three Theories of Young and
Helmholtz Experimental confirmation of this theory Partial para-
lysis of the aptitude for experiencing sensations of colour Experi-
ments which raise to a maximum the sensation of violet and of red
The three elementary sensations are those of red, violet, and pro-
bably green 117
II. Construction of the various sensations of spectral colour by the com-
binations of these elementary sensations Sensation of white Com-
plementary colours Law governing the mixture of spectral colours
Their saturation and their proximity to white Sensation of black
or want of retinal sensation It furnishes a new element for the
composition of the various total sensations of colour Different
examples Summary We cannot distinguish by consciousness the
elements of the elementary sensations of colour Why Analogy of
these elementary sensations and the elementary sensations of sound
Proof that there are elements in these as in the others Wheat-
stone's experiment Enormous number of successive elements com-
posing an elementary sensation of colour Indications and conjectures
as to the ultimate elements Consciousness perceives aggregates
only 121
III. Total sensations of taste and smell Increased difficulties
Reason of these difficulties Preliminary distinctions Smell Sen-
sations of smell strictly so called must be separated from those of
nasal touch Examples And from those of the alimentary canal
Examples And from those of the nerves of the air-passages
Examples We thus isolate sensations of pure smell Their types
Taste Sensations of taste strictly so called must be separated
from other accompanying sensations Accompanying sensations of
smell and of nasal touch Accompanying sensations of temperature
and touch in the mouth Sensations of taste proper, vary with the
different parts of the mouth Experiments of Guyot and Admyrault
Extreme complication of the sensations of taste and even of those of
xx CONTENTS.
PAGE
pure taste Their types The action of the olfactory and gustatory
nerves probably has, as immediate antecedent, a chemical com-
bination, that is to say, a system of molecular displacements
Analogy between this antecedent and the vibration of ether which
excites the action of the retina Indications as to the mode of
action of the olfactory and gustatory nerves Most probably it
consists in a succession of actions, similar to one another and ex-
tremely short, each of which excites an elementary sensation of
smell or taste Theory of the four special senses Each of them is
a special idiom constructed to represent a single order of facts
General theory of the senses They are all idioms The sense of
touch is a general idiom . . 125
IV. Total sensations of touch Increasing difficulties Reason of
these difficulties Preliminary distinctions First group of sen-
sations of touch ; muscular sensations Cases of paralysis in which
they are absent Observations of Landry The two groups of nerves
are distinct The two groups of sensations are similar There are
three kinds of sensations for all the nerves of touch Sensations of
contact, of temperature, of pleasure and pain Each of these three
kinds may be singly preserved or abolished Observations on sick
persons Known conditions of each kind Experiments and ob-
servations Opinion of Weber These distinctions are distinct
types of activity for the same nerve Experiments of Pick The
different characters we find in the aggregate sensations of contact,
temperature, pleasure, and pain, are capable of being explained by
the different arrangement of the same elementary sensations . . 134
V. Summary Blanks in the theory Researches which may supply
them The nervous action which excites a sensation is never more
than a displacement of nervous molecules To this elementary dis-
placement corresponds an elementary sensation The differences
of total sensations are all caused by the diversities of grouping
of the same elementary sensations General process and economical
method followed by nature in the construction of the mind . . 145
CONTENTS.
BOOK IV.
OF THE PHYSICAL CONDITIONS OF MENTAL EVENTS.
CHAPTEE I.
OF THE FUNCTIONS OF THE NERVOUS CENTRES.
PAGE
I. Conclusion of psychological analysis Commencement of physio-
logical analysis . f . 151
II. The external physical event is an accessory and distant condition of
the sensation It only excites the sensation through a medium ; the
excitation of the nerve Different kinds of sensitive nerves Each
has its special action The action of each is different Every
nerve is capable of spontaneous action Subjective and consecutive
sensations Altered sensations Experiments and observations of
Physiologists 152
III. The nerve is a simple conductor Molecular action must be propa-
gated from its peripheral to its central extremity Whatever may
be the point of its course from which the molecular action starts, the
sensation is the same Illusions of persons who have suffered
amputations The action of the nerves only excites sensation
through a medium, the action of the nervous centres In what
the molecular movement propagated in the nerve consists It may
be propagated in both directions Experiments of Bert and
Vulpian If any nerve when irritated excites a certain sensation it
is from its central extremity being in connexion with some portion
of the nervous centres The simple excitation of the nervous centres
is sufficient to produce sensation Proof by hallucinations Instances
observed by writers on insanity Hallucinations following the pro-
longed use of the microscope Observations of M. Robin Action
of the nervous centres is the necessary and sufficient condition of
sensation 155
IV. The different portions of the encephalon The rachidian bulb
When it alone is preserved, there are no longer sensations strictly
so called Experiments of Vulpian Distinction between the reflex
cry and cry of pain The annular protuberance Experiments of
Longet and Vulpian The action of the protuberance is the suf-
ficient and necessary condition of sensations of touch, of hearing,
and of taste The corpora bigemina or quadrigemina Experiments
of Flourens, Longet, and Vulpian The action of these tubercles
xxii CONTENTS.
PAQK
is the sufficient and necessary condition of sensations of sight
Probable existence of another centre whose action is the necessary
and sufficient condition of sensations of smell 161
V. The action of these centres is the sufficient and necessary condition
of crude sensations Accordance of the results of Physiology and
Psychology Structure of the encephalon The cerebral lobes or
hemispheres Their grey substance Relation of intelligence to the
volume and extent of this grey substance The action of the cerebral
lobes is the sufficient and necessary condition of images or reviving
sensations, and consequently of all the mental operations which
outstep the limits of crude sensation Experiments of Flourens and
Vulpian Accordance of pathological observations 165
VI. Internal structure of the cerebral lobes Their white substance is
conducting only Functions of the grey substance Physiological
and pathological proofs Gaps in physiology The various depart-
ments of grey substance fulfil identical functions, and form a group
of repeating and multiplying organs Pathological and physio-
logical proofs One hemisphere supplies the place of the other A
portion of the hemispheres, if large enough, supplies the place of
the rest Application of psychological data One element of the
hemispheres repeats the action of the sensory centres, and transmits
it to the other elements Why the magnitude of the hemispheres
and the development of their cortical layer increases the extent of
the intelligence Mechanism of the formation, survival, and indefinite
repetition of images Physiological causes of the conflict, pre-
ponderance, and succession of images Latent images To what
physiological state of the cerebral elements they correspond The
predominant image corresponds to a physiological action propa-
gated through the majority of the cerebral elements The image is
so much the weaker as the cerebral elements in which the corre-
sponding physiological action takes place are the less numerous-
All we can know by consciousness are aggregates The latent state
is but the rudimentary state j^j
VII. Summary Beneath aggregates observable by consciousness lie
their elements, which are invisible to consciousness Characters
and signs of elementary mental events Reflex phenomena Ex-
periments of Vulpian, Landry, Duges, and Claude Bernard Indi-
cations of mental events in the inferior and secondary nervous
centres The segments of the marrow Probable analogy of these
events and elementary sensations Successive degrees and constant
correspondence of the molecular movement of a nervous centre, and
the mental event , OA
' loU
CONTENTS. xxiii
CHAPTER II.
RELATIONS OF THE FUNCTIONS OF THE NERVOUS CENTRES, AND MENTAL
EVENTS.
PAGE
I. Distinction of physical and moral The second order of facts is
connected with the first This connexion seems inexplicable
Advantage of the preceding reductions and of the theory of ele-
mentary sensations 187
II. Situation of the difficulty Notion of molecular movement in the
cells and fibres of the nervous centres Even if we suppose it to be
completely elucidated we still find its idea and that of a sensation
are irreducible to one another 188
III. Another method of investigation The two ideas may be irre-
ducible to one another without the two orders of facts being irre-
ducible to one another Two objects seem different to us when we
acquire their ideas in different ways Examples This general law
is applicable to the present case Absolute difference between the
process by which we acquire the idea of a sensation and the process
by which we acquire the idea of the nervous centres and their mole-
cular movements The two ideas must be irreducible to one another 190
IV. Another series of reasons The aspect of the sensation, and that
of its ultimate elements must be wholly and entirely different
Hypothesis of two heterogeneous events Hypothesis of one and
the same event known under two aspects. Results of the first
hypothesis It is unscientific Probability of the second
Of the two points of view that of consciousness is direct, and
that of external perception is indirect The molecular movement
is but a sign of the mental event Direct and remarkable confir-
mation of the second hypothesis The sensation and its elements
are the only real events of nature Rudimentary and infinitesimal
sensations The nervous system is but an apparatus of complication
and perfectionment Presence of elementary mental events in the
whole organized world Their probable presence below this Double
scale and corresponding stages of the physical and moral world . . 193
V. The two faces of nature Clear and obscure portions of the physical
world Clear and obscure portions of the moral world To the clear
portions of the one correspond obscure portions of the other, and
reciprocally Each of them by its bright parts lightens up the
obscurities of the other Comparison of the two aspects to an in-
complete text accompanied by an incomplete translation . . . .197
xxiv CONTENTS.
CHAPTER III.
THE HUMAN PERSON AND THE PHYSIOLOGICAL INDIVIDUAL.
PAGE
I. Usual opinion as to the human personality and its faculties Mean-
ing of the word faculty or power Mechanical forces Force of
w ill These words do not denote any occult being All they denote
is a character of an event, that is to say, its particularity of being
constantly followed by another Metaphysical illusion erecting
forces into distinct essences ,..201
II. Metaphysical illusion forming of self a distinct substance Meaning
of the verb to be Our successive events are the successive com-
ponents of our self In what the faculties of the Ego consist
Examples 204
III. Progressive ruin of scholastic entities Scientific idea of forces and
beings Its application to self and to matter Mathematical idea
of atoms A real substance is nothing more than a distinct series
of events A force is nothing more than the property of one of
these events, to be followed by one of the same series or of another
series Idea of nature 209
IV. The series which makes up the Ego is a fragment in the whole
aggregate of animal functions Physiological aspect Order of
nervous centres and nervous activities The ganglia, the segments
of the marrow, the layers of the encephalon Psychological aspect
Order and increasing complication of the mental events indicated or
proved in the different centres In proportion as the animal descends
the zoological scale, the different centres become more and more
independent Experiments and observations of Duges, Landry,
Vulpian Fundamental plurality of the animal The individual,
animal or human, is nothing more than a system 211
CONTENTS.
PAET THE SECOND.
OF THE DIFFERENT KINDS OF KNOWLEDGE.
BOOK I.
THE GENEEAL MECHANISM OF KNOWLEDGE.
CHAPTER I.
OF ILLUSION.
PAGE
I. Summary of the first part Elements of human knowledge
Principal compounds formed by their combinations The formation
and rectification of illusions are two processes by which our various
kinds of knowledge are built up in our minds 216
II. Examples Illusion produced at the theatre Optical illusions
Illusions of persons who have lost limbs The sufficient condition of
belief or affirmative judgment is the presence of the ordinary sensa-
tion It does not matter whether the sensation be accompanied by
its ordinary antecedents Proofs When the condition of the mental
process is given, it is pursued blindly, as in the case of the vital
process 218
III. Consequences of this External perception is a true hallucination
Examples In the normal and ordinary state, our dream within
corresponds to things without Psychological illusion as to external
perception We are tempted to take it for a simple spiritual act
Analogous psychological illusion as to other acts of cognition . . 221
IV. Part played by the image which is substituted for sensation It
excites the same hallucinatory process Examples Case in which
this process becomes developed Observations of M. Maury on
hypuagogic hallucinations Hypnotism and somnambulism Braid's
experiments on suggestion Cases mentioned by Dr. Carpenter
Experiments of Dr. Tuke Predominance of images and of the
action of the hemispheres 225
xxvi CONTENTS.
PAGE
V. Consequences Presence of images in all sensible representations and
in all pure ideas And again, in all external perceptions, recol-
lections, previsions, and acts of consciousness General tendency
of the mind to hallucination In all our mental operations, there
is an hallucination, at all events in an incipient state Examples
of its development Mental phrases which become external voices
Effaced images which, on revival, become hallucinatory Our various
mental operations are but the various stages of this hallucination . 231
CHAPTEE II.
OF RECTIFICATION.
I. Example of rectification Case of reverie Double effect of the anta-
gonist reductives. The representation grows weak and ceases to
appear a real object Even when the representation remains distinct
and coloured, it ceases to appear a real object General mechanism
of this last rectification It consists in a negation It is accom-
plished by the attachment of a contradictory representation-
Various points on which the contradiction may attach .... 238
II. Applications Kectification of theatrical illusions Rectification of
optical illusions Rectification of illusion by a person who has lost
a limb Rectification by a person under hallucination of his
illusion The illusion is checked either at its first, or at one of its
subsequent stages 239
III. Various states and degrees of the contradictory representation-
Case in which it is feeble Case in which it is intense Case in
which it is transformed into a sensation Physiological theory of
these different states Persisting action of the centres of sensation-
Reflected action of the hemispheres on the centres of sensation . . 242
IV. Abnormal state and maximum degree of the representation The
antagonist sensation is then ineffectual and the contradictory repre-
sentation is not a sufficient reductive-The contradictory repre-
sentation is only effectual upon groups of images of no higher
degree than its own
V. Normal state of wakefulness-Example-The first stage of rectifica-
jon, recollection-The present image appears as a past sensation-
ecollection like external perception, is an illusion which results in a
cogn.tion-Our present dream corresponds to an anterior sensation-
ologuad illusion respecting memory-We are tempted to take
nowledge of our past states for a simple spiritual act
VI. Mechanism of memory-Examples-The present sensation negatives
the survmng .mage of the anterior sensation-It negative, the
mage only as being a contemporary sensation-The ordinary hal!
Amatory process checked in one point only-The saving
image appears as a sensation which is not present-Causes of itf
247
CONTENTS. xxvii
PAGE
apparent recoil Every image occupies a fragment of duration and
has two extremities, one anterior and one posterior Circumstances
casting it back into the past Circumstances projecting it into the
future Examples Successive displacements and apparent wan-
derings of the image prior to situating its'elf at a greater or "less
distance in the past or future It becomes situated by intercala-
tion and enclosure 251
VII. Last stage of rectification Examples The image then appears as
a pure present image Representations, images, conceptions, and
ideas strictly so called Cases in which they are blunted and de-
prived of individual peculiarities In this case, they cannot become
situated either in the past, the present, or the future Cases in which
they are precise and provided with individual peculiarities Pic-
turesque or poetical vision In this case, they are promptly excluded
from their apparent place in the present, the past, or the future
In both cases, the complete repression is immediate or prompt It
is the common result of the present sensation, of connected recol-
lections, and ordinary previsions 255
VIII. Psychological illusion as to consciousness We are inclined to take
the knowledge of our present state for a simple and spiritual act of
mind The representation, conception, or idea, recognised as such,
is but one and the same fact at two periods, in the state of illusion
and in that of repressed illusion Common process by which our
different kinds of cognitions are built up 260
BOOK II.
THE KNOWLEDGE OF BODIES.
CHAPTER I.
EXTERNAL PERCEPTION AND THE IDEAS OP WHICH THE IDEA OF
BODY IS COMPOSED.
I. General character of external perception It is a true hallucination
The proofs in detail Its first phase is a sensation, and this sensation
is in itself sufficient to excite the semblance of an external body
present or absent After perception, there is within us, together
with the image of the sensation experienced, a semblance of the
object perceived, and this representation tends to become halluci-
natory In many instances the apparent object differs from the real
object Three marks of the semblance Whether confounded or
not, in whole or in part, with the real object, it always follows the
sensation 263
b
xxviii
CONTENTS.
II. In what the semblance consists It coir prises, among other elements,
the affirmative conception of a thing possessed of properties Ana-
lysis of this conception, notion, or idea A thing is nothing more
than the aggregate of its properties A substance is nothing more
than an aggregate of subsisting properties A body is nothing more
than a cluster of sensible properties 268
III. Sensible properties of bodies Bodies as odorous, sapid, sonorous,
coloured, hot, or cold All we understand by these properties is the
power of exciting in us some particular kind of sensation Bodies
as solid or resisting Stuart Mill's analysis Primitively, resistance
is nothing more to us than the power of arresting a commenced
series of muscular sensations Bodies as polished, rough, pungent,
smooth, hard, soft, sticky, damp All we understand by these pro-
perties is the power of exciting some particular mode or modification
of a sensation or of a series of muscular and tactile sensations . . 269
IV. Geometrical and mechanical properties of bodies Extension, figure,
situation, mobility These notions combined with that of resistance
form the essential part cf the notion of body They are compounds
whose elements are notions of distance Bain's analysis A muscular
sensation more or less intense gives us the notion of resistance A
longer or shorter series of muscular sensations gives us the notion of
greater or less distance Notion of distance in one direction or notion
of linear extension Notion of distance in more than one direction,
or notion of extension of surface and volume Notion of position
Notion of form An entire series of muscular sensations may be
exhausted in a greater or less time Notion of velocity Double
sensible measure of the amplitude of the same movement effected by
the same limb Final notion of the transit effected or of the space
passed through Mill's theory To what the notion of empty space
traversed and of continuous solid extension are reducible All the
properties of bodies are reducible to the power of exciting sensations 272
V. Analysis of the word power It signifies that certain sensations are
possible under certain conditions and necessary under certain con-
ditionsEvery property of a body is reducible to the possibility of
a certain sensation under certain conditions and to the necessity of
the same sensation under the same conditions with a complementary
one added Confirmation of this paradox These possibilities and
necessities are lasting and independent These two properties' are
the essential characters of substance By degrees, they come
into opposition to transient and dependent sensations, and seem to
be data of a distinct kind and of a higher importance Develop-
ment of this theory by Stuart Mill 279
VI. Addition to the theory Bodies are not only permanent possibilities
of sensation, but also permanent necessities of sensation In this
respect, they are forces What a body is with respect to us What
a body is with respect to another body Three groups of properties
CONTENTS. xxix
PAGE
or powers in a body These powers are otherwise never defined than
by their relation to the events of the sentient subject, of the body
itself, or of another body Among these powers there are some to
which the others are reducible Among these events, there is one,
motion, which may be substituted for the others Scientific Idea
of body as of a moveable motor Scientific Idea of solidity,
vacuum, line, surface, volume, force, defined with relation to
motion The elements of all these ideas are never anything more
than sensations and more or less elaborate extracts from sensation . 289
VII. Correction applied to the theory Bodies are not only permanent
possibilities and necessities of sensation Process by which we
attribute to them motion Analogies and differences between this
process and the process by which we attribute to animated bodies
sensations, images, ideas, and volitions similar to our own . . . 293
VIII. Summary Materials by whose assemblage the notion or conception
of a body is formed Animal portion of this conception Human
portion of this conception Employment of names Intervention of
metaphysical illusion First elements of the hallucinatory semblance 298
CHAPTER II.
EXTERNAL PERCEPTION AND THE EDUCATION OF THE SENSES.
I. We assign a locality to our sensations This operation is distinct
from sensations and requires a certain lapse of time to accomplish
Experiments of physiologists 301
II. Sensations of touch are not situated at the spot in which we place
them What is produced there is, in the normal state, a nervous
v disturbance which is one of their antecedents Illusion of persons
who have lost limbs Observations and experiments of Mueller
Diseases and compressions of the nervous trunk Sensations wrongly
localized by paralytic persons insensible to pain Sensations wrongly
localized after autoplastic operations Experiments and observa-
tions of Weber Law governing localization We situate our sensa-
tion at the spot in which we have been accustomed to meet with its
usual condition or cause 302
III. Consequences We situate our sensations of sound and colour beyond
the limit of our body Examples Alienation of our sensations of
colour They seem to us a property of the coloured bodies Mecha-
nism of this alienation Proof that colour is nothing more than a
sensation excited by a state of the retina Subjective colours
Subjective sensation of complementary colours Luminous figures
arising from the compression of the eye Sensation of light excited
by the section of the optic nerve Visual sensations produced by
the prolonged or reflected excitation of the visual centres Various
applications of the law governing localization Part of exploring
touch Case in which the situation of the sensation remains vague
XII CONTENTS.
PAGE
Internal sensations Case in which the places assigned to the causes
of two nervous disturbances is the inverse of the places of the dis-
turbances themselves Images are inverted on the retina Two
stages of the localizing judgment Why it is sensations of colour
and sound go through these two stages Why it is sensations of
contact, pressure, and taste go through the first only Intermediate
position of sensations of smell and of heat Ambiguous character of
sensations of smell, heat, and coM which seem to us to be partially
sensations and partially properties of a body Summary The
localizing judgment is always false Its practical utility .... 308
IV. Elements of the localizing judgment Examples It is composed of
tactile and muscular images or of visual images Tactile and mus-
cular Atlas We can ascertain its presence in the ca-se of persons
born blind Case in which we can ascertain its presence in our-
selves Examples How this tactile and muscular chart performs
its functions It is primitive Visual Atlas It is ulterior The
localization of a sensation is effected by the adjunction of the visual
or tactile and muscular images attached to the sensation In the
case of instinct, this adjunction is spontaneous With man, it is an
acquisition of experience 319
V. Differences of the two Atlases Spontaneous formation of the tactile
and muscular atlas Derived formation of the visual atlas Pri-
mitive localization of visual sensations Crude sensations of the
retina What is added to them by the education of the eye Ob-
servations made on persons born blind and restored to sight by an
operation Cases recorded by Cheselden, Ware, Home, Wardrop,
and Nunneley To the retinal and muscular sensations of the eye is
added the image of the muscular sensations of transport and loco-
motion of the limbs and whole body This association is an effect of
experience Opinion of Helmholtz The retinal and muscular sensa-
tions of the eye become abbreviatory signs Analogy between these
sensations and names They are, like names, substitutes of images
Usually, these images remain in a latent state and cannot be dis-
tinguished by consciousness Comparative process by which we
estimate great distances We then compare signs only .... 323
VI. First notion of visible extension A very short series of muscular
and retinal sensations of the eye is the substitute of a very long series
of tactile and muscular sensations of the body and limbs Manner
in which persons born blind imagine extension How it is that we
believe that we perceive by sight a great number of distant and co-
existing points The visual atlas is an abbreviatory summary of
the tactile and muscular atlas Greater convenience and almost
exclusive employment of the visual atlas Circumstances in which
the tactile and muscular atlas is still employed It remains atrophied
and rudimentary, through the predominance of the other Case in
which the other cannot develop^ itself Perfection of touch in blind
persons Instances ... QQQ
CONTENTS. xxxi
PAGE
VII. Consequences of the situation our sensations appear to have They
appear extended and continuous Consequently, the bodies which
we know by means of them appear extended and continuous How
far this belief is misleading The idea of extension is not innate
but acquired Idea of our body Corporal enclosure of the Ego
Idea of an external body We conceive it, with reference to our
localized sensations, as a thing beyond it ; and, with reference to our
body, as a thing without it Projection of sensations of sight and
hearing into this outer world Their definitive alienation Com-
pletion of the internal semblance which at present constitutes for
us an external perception Why it appears as other than ourselves,
and without us 345
VIII. How far this hallucination is true in the normal state Our illusion
is equivalent to a cognition What there is of truth in the loca-
lizing judgment At the spot in which the sensations of the first
group appear situated is found situated the starting point of the
nervous disturbance At the spot in which the sensations of the
second group appear situated is found situated the starting point of
the undulation of air or ether What there is of truth in the exter-
nal perception To the differences which distinguish the sensations
of the second group correspond differences in the type of the undu-
lations and in the characters of their starting points To the cor-
poral substance we pronounce permanent there correspond a per-
manent possibility and necessity of sensations, and, in general, of
events Every external perception is reduced to the assertion of a
general fact conceived with its conditions Usual accordance of the
real and mental law General adaptation of the internal order to
the external order Spontaneous establishment, progressive per-
fection, very simple mechanism of this adaptation 350
BOOK III.
THE KNOWLEDGE OF MIND.
CHAPTER I.
THE KNOWLEDGE OF MIND.
I. Part of the Idea of Self in mental life Its almost incessant
presence The Ego compared with its events 356
II. Ideas of which the Idea of the Ego is composed Among other
ideas it comprises that of a permanent being connected with a
certain organized body What we mean by this connexion More
precise ideas of which the Idea of the Ego is composed Idea of a
group of capacities or faculties 357
xxxii CONTENTS.
PAGB
III. What we understand by the words capacity and faculty They only
denote the possibility of certain events under certain conditions
and the necessity of the same events under the same conditions,
with the addition of a complementary one These possibilities and
necessities are permanent Capital importance which we attach to
them Metaphysical illusion which their name excites The only
real elements of our being are our events 358
IV. The distinctive character common to all these events is to appear as
internal Examples Mechanism of the rectification Every repre-
sentation, conception, or idea, at its second moment, is compelled to
appear as internal Our emotions and volitions are but the affective
and active side of our ideas Hence it follows that they also must
appeal* as internal The sensations which we localize in our bodies
appear as internal The sensations which we localize outside our
bodies appear as events foreign to us or as properties of bodies
foreign to us 361
V. Our past as well as our present events appear internal^The series
of these events appears as a chain Mechanism of memory which
binds them together link by link By the law of the revival of
images, the image of one of our events calls up those of the pre-
ceding and following one Abbreviatory process by which we
quickly ascend or descend long distances in the whole series
Examples Prominent points of our past life We leap from pro-
minence to prominence Effect of this rapid survey Disengage-
ment of a character common to all the successive elements of the
series Idea of a stable within This idea is the idea of Self
Completion of this idea by that of permanent faculties and capa-
cities Final opposition of the Ego and its events 363
VI. To what real compound the idea of Self actually corresponds It is
the product of a long and complex elaboration Preliminary opera-
tions required to form it It is, therefore, susceptible of error
Various classes of errors with respect to self Case in which exter-
nal events are introduced into the idea of self Various examples
Starting point of the illusion In novelists In uncultivated minds
In dreams With madmen In hypnotism Case in which events
appertaining to self are attributed to another Normal alienation of
sensations of sound and colour Psychical hallucinations Intellec-
tual conversations of mystics Story of Blake Other examples
Starting point and progress of the illusion Passage from the
psychical to the sensorial hallucination Case in which the whole
series of our past, present, and possible events is replaced by an exter-
nal series Starting point of the illusion Suggestions in hypnotism
-Experiments of Drs. Tuke and Elliotson Examples among mono-
maniacsPatients persuaded that they are some person other than
themselves, that they are changed into animals or into inanimate
bodies, that they are dead Analogous beliefs in dreams Me-
chanism of the idea of self in the normal state Mechanism of
CONTENTS, xxxiii
PAQH
the idea of self in the abnormal state Analogy between the
mental and the vital process 368
VII. General veracity of recollection Given the mechariism of recollec-
tion its play is usually sure To the clear and circumscribed present
image, there almost invariably corresponds an antecedent sensation
of which the image is the remnant To the apparent position of
the driven back image there almost invariably corresponds the real
position of the antecedent sensation General veracity of the notion
we have of our faculties Incessant experience controls, rectifies, and
consolidates it Cohesion of its elements Exceptional circumstances
must occur in order to disjoin these elements or to insert foreign
ones among them General reason for the agreement of our thoughts
and things 379
VIII. How, from the idea of our own mind, we form the idea of other
minds Analogy of other living bodies and our own This analogy
suggests to us by association the idea of a mind similar to our own
Various, numerous, and constant verifications of this spontaneous
induction 383
IX. General summary and connected view In all the preceding opera-
tions, an image or group of images is consolidated with a sensation
or a group of sensations, with an image or a group of images, by
virtue of the laws of the revival and association of images In-
creasing complication of the mental compound Enormous compli-
cation of the compound which constitutes the idea of an individual
Every mental compound is a couple and, in this respect, a cognition
When the first term of the couple is repeated by the present sen-
sation, the second term becomes a prevision Mechanism of the
prevision and projection of the second term into the future In the
majority of instances, our prevision agrees with the foreseen event
Usual correspondence of the mental with the real law Two states
of the mental couple It acts before being distinguished Opposition
of animal to human thought Passage from the first to the second
After ideas of individual things, rise ideas of general things. . . 384
xxx iv CONTENTS.
BOOK IV.
THE KNOWLEDGE OF GENERAL THINGS.
CHAPTER I.
OF GENERAL CHARACTERS AND GENERAL IDEAS.
PAGE
General characters Examples They are the object of general
ideas 391
1. General Ideas ivhich are Copies.
I. Part of general characters in nature A group of general characters
common to all the moments of a series of events constitutes the indi-
vidual A group of general characters common to many individuals
constitutes the class General characters are the fixed and uniform
portion of existence They are not pure conceptions or fictions of
our mind Their effectiveness in nature They are more or less
general The more general they are, the more abstract they are . . 392
II. To these general extracts, general and abstract ideas correspond in
our minds These ideas are names usually accompanied by a vague
sensible representation Examples The sensible representation is
a residue of many blunted and confounded recollections The name
is a significant sound, that is to say, a sound connected with that
which all the sensible perceptions and representations of the indi-
viduals of the class have in common, and connected with that alone
In this respect it is the mental representative of their common
portion and becomes a general idea Mechanism of this exclusive
connexion Observations on children Analogy of infantile and
scientific invention In what human intelligence is distinguished
from animal intelligence How, in the child, transmitted names
become significant words Indications furnished by its barbarisms
Observations of Dr. Lieber The child receives words, but creates
their meanings 396
III. Gradual adaptation of general ideas to things Scientific research-
To the general characters whose group constitutes a class we add
others This addition has no limit Corrections afforded by these
additions to the general idea Instances in zoology and chemistry
Perfectionment of our classifications 403
IV. General characters appertaining to the elements of the classified
individuals Idea of the leaf in botany Idea of the anatomical
plan in zoology Idea of electric action Idea of gravitation Dis-
CONTENTS. xxxv
PAOB
engagement of the most universal and most stable characters
Retrenchment of accessory and transient characters Summary
The general idea is adjusted to its object, first by addition, then
by subtraction 406
2. General Ideas which are Models.
I. General Ideas whose objects are possible only We construct such
ideas Ideas of Arithmetic Notion of Unity The property of
being an unit is nothing more than the aptitude of entering as an
element into a collection All facts or individuals present this
property We isolate it by means of a sign which becomes its
mental representative Successive inventions of different kinds of
signs to represent the series of abstract units First forms of cal-
culation The ten fingers Pebbles Addition and subtraction by
means of the fingers and pebbles Names of number, substitutes
for fingers and pebbles Convenience, small number and simple
combinations of these new substitutes Final substitutes, cyphers
They are the most abbreviatory of all We thus form collections of
mental units without thinking of adapting them to collections of
real units Subsequently and through experience, every collection
of real units finds itself adapted to a collection of mental units
Examples Our numbers are preliminary outlines 409
II. All the general ideas we construct are preliminary outlines Ideas
of geometry Notions of the surface, the line, and the point
Their origin The surface is the limit of the sensible body, the line
is the limit of the surface, the point is the limit of the line Con-
venient symbols by which we represent these general characters
Surface of the board or paper, lines and points in ink or chalk
Analogy between these substitutes and the fingers or pebbles in
arithmetic Last general idea introduced into geometry, the idea
of motion Its origin New aspect it gives to the primary ideas of
geometry The line is the continuous series of the successive
positions of the point in motion The surface is the continuous
series of the successive positions of the line in motion The solid is
the continuous series of the successive positions of the surface in
motion If for the point, line, and surface, we substitute their
symbols, these constructions become sensible Other constructions
The straight line The broken line The curved line The angle
The right angle The perpendicular The polygon The circum-
ference The plane The three solids of revolution The sections
of the cone Indefinite number of these constructions To the
most general of these mental constructions there are real construc-
tions which correspond There are in nature, surfaces, lines, and
points, at least so far as our senses are concerned There are in
nature surfaces, lines, and points in motion To the least general
of these constructions there are real constructions which approxi-
mately correspond Why this correspondence is approximate only
414
xxxvi CONTENTS.
^
Examples The real construction is more complex than the mental
construction The two constructions become mutually adjusted by
the complication of the one and the simplification of the other-
Utility of preliminary outlines
III. Ideas of mechanics Notions of rest, motion, velocity, force, mass
Their origin and their formation Lines, cyphers, and names are
their symbols Diversity and indefinite number of the compounds
constructed with these elements To the most simple of these
mental constructions there are real constructions which correspond
Tendencies of bodies at rest or possessed of an uniform rectilinear
motion to persevere indefinitely in their state To such of these
mental constructions as are less simple there are also certain real
constructions which correspond Hypothesis of uniformly accele-
rated velocity ; case of heavy bodies which fall A moveable body
acted on by a uniform rectilinear movement and by another move-
ment whose velocity is uniformly accelerated ; case of the planets
How preliminary outlines must be constructed to have a chance of
agreeing with things Three conditions Their elements must be
fashioned in accordance with the elements of things Their elements
must be the most general possible Their elements must be com-
bined as simply as possible 419
IV. Other mental constructions We may form such for all classes of
objects Physical and Chemical hypothesis Among these outlines
there are some to which we are desirous that things should conform
Mental Construction of the Useful, the Beautiful, and the Good
These outlines, so constructed, become springs of action .... 423
CHAPTER II.
THE COUPLES OP GENERAL CHARACTERS AND GENERAL PROPOSITIONS.
I. General characters form couples Two general characters coupled
together form a law To conceive a law, is mentally to enounce a
general proposition 425
II. Examples of these coupled characters Practical utility of their con-
nexions These connexions are of various kinds Unilateral or
simple connexions Bilateral or double connexions -The two cha-
racters may be simultaneous They may be successive Antecedent
and consequent Frequency of this last case The antecedent
then takes the name of cause . 426
III. In what the connexion consists Stuart Mill's analysis The word
Cause does not denote any secret and mysterious virtue comprised
in the first character Its precise meaning Given the first cha-
racter, that is enough for the second to be also given There
is nothing strange in general characters having, like particular
facts, antecedents, companions, and consequents The difficulty is,
to isolate the general characters Two artifices of method for
evading the difficulty Two kinds of Laws . . . ... 428
CONTENTS. xxxvii
1. Laws concerning Real Things.
PAOB
I. First general judgments of the infant Mechanism of their forma-
tion Passage from animal judgment to human judgment General
judgments become multiplied They are the summary and measure of
anterior experience How subsequent experience rectifies them
Gradual adaptation of our couples of mental characters to the couples
of real characters We believe at present that every general cha-
racter is connected with another Provisional admission of this
hypothesis It is the principle of Scientific Induction 432
II. Various methods of Scientific Induction When a known character
is given, this is sufficient to give another character which was un-
known Search for the unknown character from this indication
Method of Agreement Method of Difference Method of con-
comitant variations Various examples All these methods are
processes of elimination They are efficient in proportion to the
magnitude of the eliminations they effect When the elimination is
complete, the residue contains the unknown character of which we
are in search Complementary method of Deduction Example
Theory of Herschel and Mill Example of these various methods in
the inquiry into the antecedent t>f dew 434
2. Laws concerning Possible Tilings.
I. Lengthiness of the processes described above Laws thus discovered
are probable only beyond the circle of our experience The most
general are last discovered 449
II. Propositions concerning possible things are different in character
Universal truth of mathematical theories We cannot conceive an
instance in which these propositions are false The most general are
formed first Among the most general, there are some called
axioms, on whioh the others depend, and which we admit without
demonstration 449
III. Two kinds of proof for the theorems of the so-called Sciences of
Construction Example Difference of the two methods of proof
Axioms are unproved theorems They are analytical propositions
We either dispense with their demonstration because the analysis
required is very easy, or evade their demonstration because the
analysis required is very difficult Axioms of identity and contra-
diction Axiom of the alternative Analysis demonstrating it
Latent ideas contained in the two members of the proposition ex-
pressing it These undisengaged ideas determine our conviction
There are latent and proving ideas of the same kind in the terms of
the other axioms 451
IV. Mathematical axioms Axioms as to equal quantities augmented or
diminished by equal quantities Experimental and inductive proof
Analytical and deductive proof Case of artificial magnitudes or
xxxviii CONTENTS.
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collections of natural units Two of these collections are equal when
they contain the same number of units Case of natural magnitudes
or collections of artificial units Two of these magnitudes are equal
when they coincide and are confounded in one same magnitude
Disengagement of the idea of identity included and latent in the
idea of equality 456
V. Principal geometrical axioms Axioms concerning the straight line
Definition of the straight line Propositions derived from it Two
straight lines having two points in common coincide in all their in-
termediate, and in all their ulterior extent Axioms relating to
parallel lines Definition of parallel lines Propositions derived
from it Two lines perpendicular to the same straight line are equi-
distant throughout Examination of Euclid's Postulate .... 462
VI. Underlying mental process which accompanies the experience of the
eyes and imagination This process consists in the silent recognition
of a latent identity The experience of the eyes and imagination is
nothing more than a preliminary indication and a subsequent con-
firmation Its utility Case in which this indication and this con-
firmation are wanting Axioms of mechanics Their late discovery
Ordinary experience does not suggest them How scientific expe-
rience discovered them Opinion which places them among truths
of experience Many of them are, in addition to this, analytical pro-
positions Principle of Inertia Exact enunciation of the axiom
The difference of place and moment is, by hypothesis, without in-
fluence or of no effect Limits of the axiom thus extended and
demonstrated Principle of the parallelogram of velocities and of
forces Exact enunciation of the axiom The co-existence of a
second movement in the same moveable body is, by hypothesis, with-
out influence or of no effect Passage from the idea of velocity to
that of force 470
VII. Axioms relating to Time and Space Mathematical Idea of Time and
Space Every determinate duration or extension has something
beyond it Analysis of this conception Every determinate magni-
tude, artificial or natural, has in the same way something beyond it,
and is found comprised in an infinite series Examples A number
A straight line Demonstration of the axiom It is an analytical
proposition Every addition effected implies an addition that may
be effected Discovery of the ideas of identity and indifference in-
cluded and latent in the terms of the axiom All the axioms we have
examined are analytical propositions more or less disguised . . . 478
VIII. Importance of the question Origin, formation, and value of axioms
and the theories derived from them Opinion of Kant Opinion of
Stuart Mill Conclusions of Kant and Stuart Mill on the range of
the human mind and on the nature of things Proposed theory
What it concedes and denies in the two preceding theories There
is an intrinsic and necessary connexion bet ween the two ideas whose
couple forms a theorem There is an intrinsic and necessary con-
CONTENTS. xxxix
PAGB
nexion between the two general characters which correspond to
these two ideas It remains for us to know whether these general
characters are actually met with in things They are met with
wherever the theorems are applicable 481
CHAPTER III.
THE CONNEXION OF GENERAL CHARACTERS, OR THE EXPLANATORY
REASON OF THINGS.
1. Nature of the Explanatory Intermediate.
I. In many cases the connexion of two data is explained What is asked
by the word why Intermediate and explanatory datum which, being
connected to the first and the second, connects the second to the
first Premises, conclusion, reasoning 487
II. Propositions in which the first datum is an individual Examples
In this ease the intermediate is a character more general than the
individual and comprised in it Propositions in which the first
datum is a general thing This is the case with laws The inter-
mediate is then the reason of the law Successive discoveries which
have determined the reason of the fall of bodies Here agaiu, the
explanatory intermediate is a more general and more abstract cha-
racter included in the first datum of the law Present hypothesis
of physicists on the explanatory reason of gravitation Same con-
clusion 487
III. Laws in which the explanatory intermediate is a transient character
communicated to the antecedent by its surroundings Law con-
necting the sensation of sound with the vibration transmitted from"
an external body Same conclusion as in the preceding case The
intermediate is then a series of successive general characters . . . 490
IV. Laws in which the intermediate is a sum of simultaneous general
characters Of the composition of causes Law of the motion of a
planet Law in which the first datum is a sum of separable data
Examples in arithmetic and geometry In this case the inter-
mediate is a general character repeated in all the elements of the
first datum Example in zoology Law of the connexion of organs
The intermediate repeated in each organ is the property of being
useful These kinds of intermediates are the most instructive
Summary The explanatory reason of a law is a general inter-
mediate character, simple or multiple, included directly or indirectly
in the first datum of the law 492
V. Of explanation and demonstration The first datum contains the in-
termediate which contains the second datum Hence three connected
propositions Order of these propositions In what the scientific
syllogism consists 498
CONTENTS.
2. Methods of finding the Explanatory Intermediate.
PAGE
I. The position and characters discovered in the intermediate afford
the means of finding it Method in the sciences of construction
Advantages they have over the sciences of experience The inter-
mediate is always included in the definition of the first datum of the
lawr We may always derive it thence by analysis Example, the
demonstration of axioms Other examples Theorem of the equality
of the opposite sides of the parallelogram How intermediates
enclose one another In what the skill and labour of the geome-
trician consist Method he follows in his constructions The more
complex compounds have simpler factors The properties of these
simpler factors are the intermediates by which the more complex
compounds possess their properties The last intermediate is always
a property of the primitive factors This property is the ultimate
reason of the mathematical law Place of axioms They enounce
those properties of the factors or primitive elements which are the
simplest and most general of all Analysis must apply, then, to the
primitive elements Primitive elements of the line Discovery of a
character common to all the elements or points of a line Definition
of a line by the constant ratio of its co-ordinates Analytical
Geometry Primitive elements of a magnitude The infinitesimal
calculus In every law enounced by a science of construction, the
ultimate reason of the law is a general character included in the
elements of the first datum! of the law 500
II. Method in the experimental Sciences Their disadvantages Insuf-
ficiency of analysis Why we are compelled to employ experience
and induction Law connecting dew with cooling Included inter-
mediates connecting the second datum of this law to the fir^t The
method of discovering the intermediate differs, according as it is a
question of real or mental compounds, but the connexion of the
second datum and of the first is formed in the same way Very
advanced experimental sciences Analogy of these sciences and of
the mathematical sciences Their most general laws correspond to
axioms They enounce, like axioms, properties of primitive factors-
How far these laws still differ from axioms They are provisionally
irreducible 508
III. Same arrangement in the less advanced experimental Sciences
Their m st general laws also enounce properties of primitive
factors Sciences in which the primitive factors may be observed
Zoology General characters of organs Cuvier's law Geoffroy
Saint- Hilaire's law History General characters of the individuals
of an epoch, of a nation, or of a race Psychology General cha-
racters of the elements of knowledge All these general characters
are explanatory intermediates They are the more explanatory in
proportion as they appertain to more general and more simple
primitive factors Explanation is at an end when we arrive at
CONTENTS. xli
. PAGE
primitive factors which we can neither observe nor conjecture
Present limits of physiology, physics, and chemistry Beyond known
factors the simpler unknown factors may have either different or
the same properties According as one or the other of these hypo-
theses is true, the explanation has or has not limits 513
IV. Another disadvantage of the experimental Sciences They have to
answer to questions of origin Historical portion of every experi-
mental science Laplace's hypothesis Researches of mineralogists
and geologists Darwin's Ideas Views of historians General
Theory of Evolution Gaps Daily progress which fills them up
The formation of a compound is explained by the properties of
its elements and by the characters of the antecedent circumstances
The explanatory intermediate is the same in this and in the pre-
ceding cases 520
3. If every Fad or Law lias its Explanatory Reason.
I. Convergence of all the preceding conclusions They indicate that,
in every couple of actually connected events, there is an expla-
natory intermediate which necessitates this connexion At all
events we believe that it is so We predict, by analogy, the cha-
racters of the intermediate in the cases in which it is still unknown
to us Examples We extend this law by analogy to all points of
space and all moments of time 525
II. Groundwork of this induction From our ignorance in certain
cases of the explanatory reason, we cannot conclude that it does
not then exist The cause of our ignorance is known to us The
gaps of science are explained by its conditions Examples To
presume the absence of the explanatory reason is a gratuitous hypo-
thesis The presumptions are in favour of the presence of an expla-
natory reason of which we are ignorant Other presumptions sug-
gested by the example of the sciences of construction In these
sciences, every law has its known explanatory reason The gaps of
the experimental sciences are caused by their conditions and by
the particular turn of their method Proof What geometry would
be if formed by induction The gaps of geometry would then be
the same as those of physics or chemistry Tho Sciences of Con-
struction are a preliminary model of that which the experimental
sciences might be Analogy of their arrangements Identity of the
materials The only difference between our mental and real com-
pounds, is that the first are the more simple Employment of
mental compounds in order to understand real compounds Conse-
quences The application of mathematical and mechanical laws is
universal and necessary Refutation of Stuart Mill All numbers,
forms, movements, arid forces of physical nature are subject to
necessary laws Very probably, all the physical changes in the
world, and probably, all the physical changes beyond our world are
reducible to movements which have movements for their conditions
xlii CONTENTS.
PAGE
Idea of the physical universe as a collection of moveable motors
subject to the law of the Conservation of Force 527
III. Eecapitulation of the inductive proofs which make us believe in the
principle of the Explanatory Reason Our natural inclination to
admit it Employment made of it by scientific men for the purpose
of induction Opinion of Claude Bernard Opinion of Helmholtz
Explanation of this belief by the innate structure of our mind
Another explanation Analogy of this principle and of the axioms
previously demonstrated It is probable that, like them, it may be
demonstrated by analysis Demonstration Latent identity of the
terms enouncing it Limits of the axiom so demonstrated and
understood The axiom of Cause is derived from it Consequences
of the axiom of explanatory reason The intervention of expe-
rience is necessary in order that it may be applied Possible appli-
cation of the axiom to the problem of existence General Summary
of the present psychological theory 534
THE END OP THE TABLE OF CONTENTS.
ERRATUM.
P. 293, lines 20-1, and elsewhere, for "moveable motive force" read
" moveable motor."
ON INTELLIGENCE,
PART THE FIRST.
THE ELEMENTS OF KNOWLEDGE.
BOOK I.
OF SIGNS.
CHAPTER I.
OP SIGNS IN GENERAL AND OF SUBSTITUTION.
^
I. IF we ascend the Arc de FEtoile, and look down on
the Champs Elysees, we see a number of black or variously
coloured specks stirring about on the roadway or pave-
ments. That is all our eyes distinguish. But we know
that each of these specks is a living body, with active limbs,
a wise economy of organs, and a thinking brain actuated
by some project or inward desire in short, is a human being.
The presence of the specks has indicated the presence of
persons. The first have been signs of the second.
Associations of this kind are continually being met with.
At night we look up to the starry sky, and say to ourselves
that each of these brilliant points is an enormous mass like the
sun. When we walk in the fields on an autumn evening,
we see the blue smoke rising calmly in the distance, and
think at once of the slow fires with which the peasants are
burning up the stubble. We turn over sheets of music,
B
-
2 OF SIGNS. [BOOK I.
and, while the eye follows the black and white marks with
which the lines are dotted, we hear mentally the sounds
they indicate. A sharp cry of a particular tone comes
from a neighbouring room, and we picture to ourselves the
face of a child, crying no doubt because he has hurt him-
self. The greater part of our ordinary judgments are made
up of connections like these. When we drink, or walk, or
use our limbs for any .purpose, we foresee, by means of a
perceived fact, a fact which we do not yet perceive ; animals
do the same; according to the colour or smell of an object,
they eat or leave it. In all these cases a present experience
suggests the idea of another possible experience ; from the
first we imagine the second : the perception of an event,
object, or character, arouses the conception of another event,
object, or character. When we touch the first link of the
couple we picture to ourselves the second link, and the first
is the sign of the second.
II. In this great family of signs there is one species
whose properties are remarkable ; these are names.
Let us first consider proper names, which are the easier
to study from each one denoting some particular, precise
thing; as, for example, the names Tuileries, Lord Palmer-
ston, Luxembourg, Notre Dame, &c. These clearly belong
to the family we have just described, and each of them is
the sensible and apparent first term of a couple. When I
hear the word Lord Palmerston pronounced, or read the
fourteen letters of which it is made up, I form a mental
image of his brisk erect figure, gesticulation, and smile, just
as I have seen him in his place in Parliament. Again,
when I read or hear the word Tuileries, I picture more or
less vaguely, in more or less mutilated forms, a level garden,
flower-beds enclosed with rails, marble statues, the rounded
heads of chestnut-trees, the fall and plume of a fountain,
and the rest. A short insignificant sensation, acting through
our eyes or ears, has the property of calling up in us a
certain image, or series of images, more or less definite, and
the connection between the first and second terms of this
couple is so precise, that in a hundred million instances,
CHAP. L] SIGNS IN GENERAL AND SUBSTITUTION. 3
and for two millions of men, the first term invariably calls
up the second.
III. Suppose now that instead of dwelling on the word
Tuileries, and calling up the different images connected
with it, I glance quickly at a phrase like this : " There are
many public gardens in Paris, both small arid great, some
no bigger than a drawing-room, others as large as a park,
the Jardin des Plantes, the Luxembourg, the Bois de
Boulogne, the Tuileries, the Champs Elysees, the squares,
besides the new parks which are being laid out, all very neat
and well looked after." I ask the ordinary reader who has
just gone through this list with ordinary speed, if, when his
eye ran over the word Tuileries, he saw mentally, as before,
some fragmentary image, some patch of blue sky appearing
through trees, the attitude of some statue, some vaguely
extending avenue, the sparkling of water in a basin ?
Assuredly not, his eye ran over it too quickly ; there is a
notable difference between this and the preceding operation.
In the first, the sign aroused pictures more or less faded of
the sensation, revivals more or less enfeebled of the expe-
rience ; in the second, the sign did not arouse them. In
.the one case, the two links of the couple appear; in the
other, the first link alone appears. Between these two
operations are an infinite number of intermediate states
occupying the whole interval ; these states connect the
intense half- sight with the dry notation, by a series of
degradations, rubbings out, and losses, which strip by degrees
the complete and puissant image, till they leave us nothing
but a simple word.
This word so reduced is not however a lifeless symbol,
without trace of signification ; it is more like the trunk of
a tree, stripped indeed of its leaves and branches, but
capable of reproducing them ; we understand it as we pass it,
and with whatever speed we may pass it ; it does not come
to us as a stranger, or strike us as an intruder; in its long
association with the experience and image of the object, it
has contracted certain affinities and repugnances ; and in
passing through us carries with it this retinue of affinities
B 2
4 OF SIGNS. [Boos I.
and repugnances ; however briefly we retain the word, the
image to which it corresponds commences to form ; the image
accompanies the word in a nascent state, and, though not
actually formed, acts on us as if it were. Read, for instance, a
sentence like this : " London, the capital of England, has
several fine gardens Hyde Park, Regent's Park, and the
Tuileries." We experience a certain shock and surprise ; we
point involuntarily in two directions, towards Paris and
towards a far distant city. The image of the Tuileries is
aroused, with the Seine and quays beside it, and we are
arrested when we try to transport them elsewhere. But before
the image appeared, we experienced a resistance in the word
itself, a resistance which was strengthened and renewed
when the image reappeared. Prolong and vary the experi-
ment : you will find in the word a system of tendencies all
corresponding to those of the image, all acquired by it in
its connection with the experience and the image, but now
spontaneous, and acting, sometimes to connect it 'with, some-
times to sever it from, other words or groups of words,
images or groups of images, experiences or groups of expe-
riences. In this way the simple name is enabled to take the
place of the image it arouses, and consequently, of the
experience it recals; it performs their office and becomes
their substitute.
IV. In the case we have considered, the obliteration of
the image forming the second member of the couple is, as
generally happens with proper names, gradual and invo-
luntary. Let us consider another case, in which we
suddenly and voluntarily suppress it ; the reader will then
see the operation more clearly set out.
My garden is surrounded by a hedge, and my fruit is
stolen ; I determine on enclosing it with a wall. I get what
workmen I can in the village four, for instance and at
the end of the day I find they have built twelve metres of
wall. This is not fast enough ; I send to the next village
for six other workmen, and ask myself how many metres
a day will be added to the wall. To find out this, I no
longer picture to myself workmen with their blouses and
CHAP. I.] SIGNS IN GENERAL AND SUBSTITUTION. 5
trowels the wall with its stones and mortar, but replace my
first workmen by the figure four, the first amount of work
by the figure twelve, the whole of the workmen by the
figure ten, the unknown amount of work they will do
by the sign x, and write down the following propor-
tion :
Henceforth, barring accident or drunkenness, if the new
men work like the old, and all continue to work together
as the first four began, my ten men will build thirty metres
a day. Operations of this kind occur daily, and all prac-
tical calculations are made in this way. For the real
objects first imagined, figures are substituted which re-
place them partially; they replace them in the only point
of view in which we need consider them, that is, in point of
number. This once effected, we forget the objects repre-
sented ; they recede into the background ; we only con-
sider the figures, we assemble, compare, transpose, and
manipulate them as more convenient equivalents, and the
figure we finally arrive at indicates the object, or group of
objects, at which we wish to arrive.
Substitution goes further than this, and figures substi-
tuted for things have in turn letters substituted for them.
After several similar calculations, I observe that in all such
cases the proportion is written in the same way, that the
first figure always represents the first workmen ; the second,
their work ; the third, the whole number of workmen ; the
fourth, the unknown work; and thus I pass from arith-
metic to algebra. Henceforth I replace the first figure by
A, the second by B, the third by C, and write down as
follows :
B x C
A : B : : C \x = -
A.
And I see that, in every such case, if I want to know the
amount of work which will be done by all the workmen, it
will be sufficient to multiply their number by that repre-
6 OF SIGNS. [BOOK I.
senting the work done by the first lot, and then to divide
the product by the number of the workmen first employed.
Instead of this simple case, let us consider the labour of
an analyst who writes equations by the hour. He lays
aside the figures, but indirectly he is working on them, just
as an arithmetician lays aside the facts, but works indirectly
on the facts. He effaces figures from his mind as the other
effaces things. Each of them arranges and combines signs,
and these signs are substitutes. The fact is, they are not, like
proper names, substituted for the whole of the object they
represent, but merely for a portion or an aspect of such object.
The letter used in algebra does not fully replace the arith-
metical cipher with its precise quantity, but only as regards
its function and place in the equation it enters into. The
arithmetical cipher does not fully replace the thing it stands
for, with all its qualities and characters, but only, as regards
quantity and number. Each replaces part only of the
imagined object, that is to say, a fragment an extract ; the
cipher a more complex extract; the letter a less complex
one, that is to say, an extract from the first extract. But
the substitution, though partial, is none the less actual. Two
complete and infinitely fertile sciences depend on it, and
derive their efficacy from it. The reader must pardon me
for dwelling on simple remarks like these. In the forma-
tion of couples, such that the first term of each suggests the
second term ; and, in the aptitude of this first term to stand,
wholly or partially, in place of the second, so as to ac-
quire, either a definite set of its properties, or all those
properties combined, we have, I think, the first germ of the
higher operations which make up man's intelligence; we
shall now consider them in detail.
CHAP. II.] GENERAL IDEAS AND SIMPLE SUBSTITUTION.
CHAPTER II.
OF GENERAL IDEAS AND SIMPLE SUBSTITUTION.
I. NAMES, as we know, are divided into proper and
common; and these are correctly distinguished by saying
that the first, as Caesar, Tuileries, Cromwell, correspond
to a single object ; while the second, as tree, triangle, colour,
correspond to an indefinite group of objects. These last
are the most numerous, and the most in use in every
individual mind; there are thirty or forty thousand of
them in a language, and they make up of themselves the
whole dictionary. Further than this, they are the most
important ; by their aid we make classifications, judgments,
and reasonings, and pass, in short, from crude, loose expe-
rience, to orderly complete knowledge. Let us consider
them attentively. We should attain a truth of capital im-
portance, and infinite in its consequences, could we deter-
mine, not as grammarians and logicians, but as psycholo-
gists, their true nature and precise office.
Like all signs, and especially like all names, each one is
the first term of a couple, and draws with it a second term.
But this second term has remarkable characteristics,which dis-
tinguish it from all others, and give the name peculiar qualities.
Logicians and grammarians tell us rightly that a common
name, like tree or polygon, is a general or abstract name.
It is general because it corresponds to a class (genus) or
group of similar objects ; the name of tree to all trees,
poplars, oaks, cypress, birch, &c. ; the name of polygon
to all polygons, triangles, quadrilaterals, pentagons, hexa-
gons, &c. It is abstract, because it denotes an extract, that
is, a portion, of an individual, and a portion which is found
in every individual of the group ; the name tree expresses
8 OF SIGNS. [Boos I.
the quality common to all kinds of trees, poplars, oaks,
cypress, birch, &c. ; that of polygon represents the quality
common to all sorts of polygons, triangles, quadrilaterals,
pentagons, hexagons, &c. We see the connection between
these two characters of a name ; it is general because it is
abstract ; it corresponds to a whole class, because the object
it denotes, being but a fragment, may be found in all the
individuals of the class, which, similar in this point, remain,
nevertheless, dissimilar in other points. Here we have a
couple of a new kind, since its second term is not an. object
of which we can have perception and experience, that is to
say, an entire and determined fact, but a portion of a fact,
a fragment forcibly and artificially severed from the natural
whole to which it belongs, and without whicli it cannot
subsist.
II. Can we have experience, perception, or sensible
representation of this detached and isolated fragment?
Assuredly not; for that would be a contradiction. When
I have seen on the slate triangles, quadrilaterals, pentagons,
hexagons, &c. ; and, in contrast, beside them, circles and
ellipses, and call the first polygons, I have not mentally a
sensible representation of a pure or abstract polygon j for
the pure polygon is a figure with several sides, but whose
sides do not make up any particular number; hence all
experience and sensible representation are excluded; for
since the sides are many, they make such a number as three,
four, five, six, &c. In saying many, we mean a determined
fixed number. To tell one to see or imagine many sides,
and at the same time not to see or imagine three, four, or
any definite number of sides, is, in one breath, to order and
forbid the same operation. Similarly, when having seen in
the country thirty different trees, oaks, lime trees, beech, and
poplars I use the word tree, I do not find in my mind a
coloured figure representative of a tree in general ; for a
tree in general has height, a trunk, leaves, &c., without
having any particular height, trunk, or leaves; and it is
impossible to represent to one's self size and form, unless the
size and form are of some kind or other that is to say, in-
CHAP. II.] GENERAL IDEAS AND SIMPLE SUBSTITUTION. 9
dividual and precise. In fact, at the word tree, especially if
read slowly and attentively, there rises in me a vague image
so vague that I cannot for the moment say whether it is a fir
or an apple tree. And so in hearing the word polygon, I
trace in my mind, but very indistinctly, lines cutting each
other, and tending to enclose a space, without knowing
whether the figure in process of construction will turn out
quadrilateral or a pentagon. But this uncertain image is
not the abstract tree, nor the abstract polygon ; the soft-
ness of its outline does not hinder its having a particular
outline ; it is shifting and obscure, and the object denoted
by the name is neither shifting nor obscure ; it is a very
precise extract, and can often be defined exactly. We can
express with rigorous exactness what constitutes a triangle,
and, almost as exactly, what constitutes an animal. The
triangle is a figure enclosed by three lines, which cut each
other in pairs, and not that undecided image, on a dusky or
whitish ground, with angles more or less acute, which
shifts continually, becoming at will scalene, or isosceles, or
right angled. The animal is an organized body which is
nourished, reproduces its species, feels, and moves, and not
that formless and varying thing, changing from vertebrate
to articulate or to mollusc, and only emerging from its
indistinctness when it takes the colour, size, and structure
of an individual.
Thus we find a wide gulf between the vague and shifting
image which the name suggests, and the precise and fixed
extract which the name denotes. The reader may convince
himself of this by considering the word myriagon and its
meaning. A myriagon is a polygon with ten thousand
sides. It is impossible to imagine such a thing even when
definite and special, much less when general and abstract.
However lucid and comprehensive may be the mind's view ;
after five or six, twenty or thirty lines drawn out consecu-
tively with great difficulty, the image becomes confused and
indistinct; and yet my conception of a myriagon has
nothing confused or indistinct about it. What I conceive,
is not a myriagon like this, incomplete and tumbling to
10 OF SIGNS. [BOOK I.
pieces, but a complete myriagon all whose parts co-exist
simultaneously; I can hardly imagine the first, but can
readily conceive the second. What I conceive then, differs
from what I imagine ; and my conception is not the same
thing as the shifting figure which accompanies it. But, on
the other hand, this conception exists ; there is something
in me representing the myriagon, and corresponding to it
exactly. In what then does this internal representative
this exact correspondent consist ? and what passes within
me when I hear a general name, and, by means of it, think
of a quality common to many individuals of a general
thing in short, of an abstract character ?
III. To answer this, let us consider in order several cases
in which, when we have gone through a series of similar
objects, we have mentally extracted from them a quality, or
general character, which we denote by an abstract name.
The reader has no doubt visited galleries of pictures
arranged in schools ; if we walk for a couple of hours among
the works of Titian, Tintoret, Giorgione, and Veronese, and
on leaving seat ourselves on a bench, and close our eyes,
we experience reminiscences of what we have seen ; we see
again inwardly such and such a fair or rosy half-bending
figure, some grand old man majestically draped in silken
robes, strings of pearls on naked arms, chestnut hair curling
over a snowy neck, colonnades of veined marble rising against
a blue sky, here and there the sprightly figure of a little
girl, the smile of a goddess, the ample proportions of a
smooth shoulder, the blaze of red hangings against a green
background; in short, a hundred partial and disorderly
revivals of what we have just seen. If, at this moment, we
seek for the dominant character ruling in this various world,
we find nothing ; we feel indeed that it is beautiful, but
do not yet distinguish in what the beauty lies ; we are acted
on by twenty different tendencies which rise and as quickly
fade ; we attempt such expressions as voluptuous, rich, facile,
luxuriant ; they are not suitable, or but partially so. We
then begin again by dividing our inquiries, we pass by turns
in review landscapes, architecture, dress, types, expressions,
CHAP. II.] GENERAL IDEAS AND SIMPLE SUBSTITUTION. 11
attitudes, colouring; we find for each of these fragments
some principal and striking trait, we attempt to note them
in passing by a familiar or exaggerated word, then, collect-
ing all these summaries we try to summarize them further
in some abbreviative phrase which may serve as a focus for
all these dispersed rays. We approach our object, and at last
a definitive, or nearly definitive, tendency is disengaged. It
appears, in words, by such expressions as expansiveness, hap-
piness, noble pleasure; while our inner sight has at the
same moment seized on some corresponding image, an open-
ing flower, a smiling face, a bending unconstrained form,
the rich and full harmony of sweet-toned instruments, the
breath of perfumed air in the country ; here are expressive
comparisons and metaphors, that is to say, sensible repre-
sentations, special recollections, revived sensations, all
analogous in tone and character to what we have just
experienced. They are effects and expressions of the final
tendency which has been formed. In the case of an
artist, the formation, disengagement, and effects of the
tendency are plainer still. The whole body speaks ; often,
if at a loss for a word, a gesture expresses the meaning ; a
grimace, a start, an imitative noise, becomes a sign in place
of a name ; to represent an avenue of old oaks, the stature
becomes erect, the feet are planted firmly on the ground,
the arms extend stiffly, or form sharp angles at the elbows ;
to represent a cluster of honeysuckle or ivy, the stretched-
out fingers trace arabesques in the air, while the muscles of
the face assume changing folds. This mimicry is natural
language, and with some habit of internal observation you
guess the corresponding mental state. In fact, the expe-
riences we undergo, and their images which recur to us,
are not pure knowledge ; they affect us while they
teach us ; they are at once a disturbance and a light. Each
one of them is accompanied by one or many slight shocks,
and each of them has for effect one or more slight ten-
dencies. Beneath images and experiences, vegetation that
thrives in the light, there is an obscure world of impulsions,
repugnances, startling shocks, sketchy, disorderly, dis-
12 OF SIGNS. [BOOK I.
cordant solicitations, which we can barely distinguish, but
which are nevertheless the inexhaustible and ever-springing
source of our actions. These are the countless little emotions
which, at the close of our prolonged examination, sum them-
selves up in an impression of a whole, and consequently, in
a final and definite tendency, and this tendency results in an
expression. Whatever this expression may be the imitative
gesture of the artist, the metaphorical half-sight of the poet,
the expressive pantomime of the savage, the animated tones
of the impassioned man, the dry tone and abstract language
of the calm reasoner the mental operation is always the
same ; and if we inquire into what passes in us when, from
several perceptions, we disengage a general idea, we find
and find only the formation, completion, and preponde-
rance of a tendency which urges an expression, and, among
other expressions, a name.
To revert to our first example. I observe in turn pines,
ash, chestnuts, beech, oak, a whole forest ; I remark the
springing trunk and spreading branches which form the
two distinctive characters of a tree ; I form a general con-
ception of a tree and use the word tree. This simply means
that a certain tendency in my mind, corresponding to these
two characters and to these two characters only has at
last become distinct and predominant. On fifty conse-
cutive occasions, and without a single contradictory instance,
it has in turn been aroused at the sight of fifty trees ; and
it only has been aroused on each one of these fifty occasions.
All other tendencies corresponding to the peculiarities of
the different trees, are effaced and annulled by mutual
contradiction ; it alone survives, and results, as do all
tendencies, in an expression. Mentally, this result is an
image, more or less vague that of a slender, then spread-
ing stem ; outwardly, it becomes the attitude and imitative
gesture of the body ; in primitive language, among infant
races, at the origin of speech, it is a poetical and figurative
imitation of another kind, of which we find fragments here
and there ; now-a-days, it has become a simple word,
which we learn purely by way of notation, the dry remains
CHAP. II.] GENERAL IDEAS AND SIMPLE SUBSTITUTION. 13
of the little symbolical drama and living mimicry by
which the first inventors, true artists, translated their im-
pressions.
IV. The reader now sees how it is we conceive a general
quality ; when we have seen a series of objects possessing a
common quality, we experience a certain tendency, a tendency
which corresponds to the common quality, and to it alone.
It is this tendency which calls up the name ; and when it
arises the name only is imagined or pronounced. We do
not perceive qualities or the general characters of things ;
we only experience in their presence such and such a dis-
tinct tendency, which, in spontaneous language, results in a
certain mimicry, and, in our artificial language, in a certain
name. We have, strictly speaking, no general ideas ; we have
tendencies to name and names. But a tendency is nothing
distinct in itself; it is the commencement, the rudiment,
the sketch, the approximation, whether easy or difficult,
to something, image, or name, or other determinate act,
which is its full development and accomplishment ; it is the
elementary form of the act which is its final state. As to
positive and definite acts, when we conceive or know ab-
stract qualities, all that passes in us are names, some in
process of being expressed or mentally imagined ; others
already expressed and imagined. What therefore we call a
general idea, a comprehensive view, is only a name ; not
the simple sound that vibrates in the air and strikes our ear,
or the collection of letters which blacken the paper and
attract the eye, not even these letters perceived mentally, or
this sound pronounced mentally, but this sound or these
letters endued, when we experience or imagine them, with
a double property, that of arousing in us images of in-
dividuals belonging to a certain class, and of these individuals
only ; and the property of reviving when, and only when, an
individual of this same class is present to our memory or
experience. The only difference between the word tree,
which has a meaning, and the word eter, which has none, is
that on hearing the second we do not imagine any object or
series of objects belonging to a distinct class, and there is no
14 OF SIGNS. [BOOK I.
object or series of objects belonging to a distinct class which
suggest to us such a word, whilst on hearing the first word
we involuntarily picture to ourselves an oak, a poplar, a
pear tree, or some other tree, and on seeing a tree, of what-
ever kind, we involuntarily pronounce the word tree. Instead
of eter put the word arbre ; to any one unacquainted with
French, the two words are of equal value, and result in the
same want of effect; to a Frenchman the word arbre has
precisely the properties which we have just found in the
word tree. A name, then, which we understand is a name
connected with all the individuals which we can perceive or
imagine belonging to a certain class, and only with the
individuals of this class. In this way it corresponds to the
common and distinctive quality which constitutes the class
and separates it from other things, and corresponds to this
quality only ; wherever the quality is, there is the name ;
whenever this quality is absent there is no name ; it is
aroused by it, and by it only. Thus it becomes its mental
representative, and the substitute of an experience to which
we cannot attain. It stands in place of this experience, it
fulfils its office, and is equivalent to it.
Admirable and spontaneous artifice of our nature : we
can neither perceive general qualities nor maintain them
separate in our minds; and yet, they are the precious
veins which constitute the essence and are the founda-
tion of the classification of things, and, to enable us to
emerge from gross animal experience, to seize the order
and internal structure of the world, we must draw
them from their ore and conceive them apart. We make
a circuit, we associate with each abstract and general
quality a little special complex fact, a sound, a figure easy
to imagine and reproduce; we make the association so
close and precise, that henceforward the quality cannot
appear or be missing in things without the appearance
or absence of the name in our minds, and reciprocally.
The couple so formed resembles those physical and chemical
instruments, which, by a trifling sensible change, the dis-
placement of a needle, the alteration of a colour, bring
CHAP. II.] GENERAL IDEAS AND SIMPLE SUBSTITUTION. 15
within the range of our senses, decompositions of sub-
stances, or variations of currents, to which our senses
cannot otherwise attain. The sudden reddening of a stained
paper or the greater or less twist of a suspended needle are
connected with an inner change or a certain degree of
hidden action, and we observe the second things to which
we cannot directly attain, in the first to which we do attain.
And similarly, when we are dealing with a general quality
of which we can have neither experience nor sensible repre-
sentation, we substitute, and substitute legitimately, a name
for the impossible representation. It has the same affinities
and repugnances as the representation, the same hindrances
to and conditions of existence, the same extent and limits
of presence; affinities and repugnances, hindrances and
conditions of being, extent and limits of presence, all we
meet in the one we meet, indirectly, in the other. Owing
to this correspondence, the general characters of things are
brought within range of our experience ; for the names
expressing them are, themselves, either small experiences of
sight, the ear, the vocal muscles, or internal images, that is
to say, revivals more or less clear, of these experiences. An
extraordinary difficulty has been surmounted ; with beings
whose life is but one varied and continuous experience, special
and complex impressions can alone be found; out of these
special and complex impressions nature has manufactured
the equivalents of others, which are neither special nor com-
plex, and which, as they cannot be so, would seem as if
they must escape for ever by necessity and nature from
beings constituted as we are.
V. The formation of these general names may bs narrowly
watched ; with little children, we take them in the act. We
name to them such and such a particular determined object,
and, with an instinct of imitation common to them with
monkeys and parrots, they repeat the name they have just
heard. Up to this point they are but as monkeys and
parrots; but here there appears a delicacy of impression
which is special to man. We pronounce the word papa
before a child in its cradle, at the same time pointing out
16 OF SIGNS. [BOOK I.
his father. After a little, he in his turn lisps the word,
and we imagine that he understands it in the same sense that
we do, or that his father's presence only will recal the
word. Not at all. When another person that is, one
similar in appearance, with a long coat, a beard, and loud
vo i ce enters the room, he calls him also papa. The
name was an individual one ; he has made it general. In
our case, it is applicable to one person only ; in his, to a
class. In other words, a certain tendency, corresponding to
what there is in common to all persons in long coats, with
beards and loud voices, is aroused in him in consequence of
the experiences by which he has perceived them. This ten-
dency is not what you were attempting to excite; it
springs up spontaneously. In it we have the faculty of
language. It is wholly founded on the consecutive ten-
dencies which survive the experience of similar indivi-
duals, and corresponds precisely to what they have in
common.
We see these tendencies continually at work in children,
and leading to results differing from ordinary language ; so
that we are obliged to correct their spontaneous and too
hasty attempts. A little girl, two years and a half old, had a
blessed medal hung at her neck. She had been told,
u C'est le bon Dieu" and she repeated, " C'est le bo Du."
One day, on her uncle's knee, she took his eyeglass, and
said, " C'est le bo Da de mon oncle" It is plain that she
had involuntarily and naturally constructed a class of objects
for which we have no name ; that of small round objects,
with a handle, through which a hole is pierced, and
hung round the neck by a riband ; that a distinct ten-
dency, corresponding to these four general characters, and
which we do not experience, was formed and acting in her.
A year afterwards, the same child, who was being asked the
names of different parts of the face, said, after a little hesi-
tation, on touching her eyelids, " These are the eye-cur-
tains." A little boy, a year old, had travelled a good deal
by railway. The engine, with its hissing sound and smoke,
and the great noise of the train, struck his attention, and
CHAP. II.] GENERAL IDEAS AND SIMPLE SUBSTITUTION. 17
the first word lie learned to pronounce was fafer (chemin de
fer). Henceforward, a steamboat,, a coffee-pot with spirit-
lamp everything that hissed or smoked, or made a noise,
was a fafer. Another instrument to which children have a
great objection (excuse the detail and the word I mean
a clysopompe] had, naturally enough, made a strong im-
pression on him. He had termed it, from its noise, a
zizi. Till he was two years and a half old, all long, hollow,
slender objects a scissors- sheath, a cigar- tube, a trumpet,
were for him zizi, and he treated them all with distrust.
These two reigning ideas, the zizi and the fafer, were
two cardinal points of his intelligence, and from them he
set out to comprehend and name other things.
In this respect the language of children is as instructive
to a psychologist as the embryonic states of organized bodies
are to the naturalist. Their language, unlike ours, is living,
and incessantly on the change ; not only are words defaced
or invented, but, more than this, the sense of words is not
the same as in our language. A child who pronounces a
name for the first time never takes it in the precise sense
which we give it. This sense is more or less extensive to
him than to us ; it is proportioned to his experience at the
time; is enlarged or reduced daily by his new experience,
and brought very slowly down to the precise dimensions
which it has for us.* A little girl, of eighteen months old,
had been heartily amused by her mother, or nurse, hiding
in play behind the door or chair, and saying, " Coucou."
Again, when her dinner was too hot; when she went too
near the fire ; when she put out her hand to the candle ;
when they put on her hat in the garden, to keep off the hot
sun, she was told " Ca brille." Here were two remark-
able words which, to her, represented things of supreme
* An analogous difference appears in comparing the synonyms in two
languages : clergyman and ecclesiastique, God and Dieu, liebe and amour, bno
and brillant, girl and jeune fille, do not respectively mean the same things, though
we translate one by the other. The two words of each couple represent two dif-
ferent objects, and are differently understood by the two peoples. Their sense is
the same in the rough ; the details of their meanings are different and untrans-
latable in the absence of similar objects and emotions in the two cases.
IS
OF SIGNS. [Boos I.
importance; her most painful sensation and her most
pleasurable one. One day, seeing from a terrace the
sun disappearing behind a hill, she said, "A bule coucou."
Here we have a complete judgment, not only expressed by
words which we do not employ, but also corresponding to
ideas, consequently to classes of objects, to general charac-
ters, to distinct tendencies, which in our cases have disap-
peared. The hot soup, the fire on the hearth, the flame of
the candle, the noonday heat in the garden, and last of all,
the sun, make up one of these classes. The figure of the
nurse or mother disappearing behind a piece of furniture,
the sun disappearing behind a hill, form the other class.
Both are limited to this; the tendency consecutive to the
first resulted in the words a bule ; the tendency consecutive
to the second in the word coucou. Such a state of mind
differs greatly from ours ; but, nevertheless, it consists of
tendencies analogous to ours, aroused in the same way as
ours, corresponding to general characters as with us, but to
characters less general, in short, resulting in names similar
in sound and different in sense.
In proportion as the experience of children approaches
more nearly to our own, their tendencies to name coincide
more exactly with ours ; they become organized by degrees
like embryos. As in the foetus, we see, in turn, the dispro-
portionate head reduced to its proper proportions, the sutures
of the skull harden, the cartilage turn into bone, the rudi-
mentary vessels close and ramify, the communication be-
tween child and mother become obstructed; so do we see,
in the language of children, the two or three dominant
words lose their absolute preponderance, the general words
limit their too extensive meaning, gain precision for their
vagueness of sense, acquire connections, attachments and
sutures with each other, become complete by the incorpora-
tion of other tendencies, become arranged under these into
names of smaller classes, form a system corresponding to
the order of beings, and at last act by themselves alone, and
of themselves, without the aid of assisting namegivers. A
child has watched its mother put on her white dress for a
CHAP. II.] GENERAL IDEAS AND SIMPLE SUBSTITUTION. 19
ball; he has remembered the word, and in future, when he
meets a lady in evening dress, whether she has on red or blue,
he will say in his singing, curious, happy voice, " You have
put on your white dress." White is too large a word ; he will
have for the future to reduce its application to a single
colour. The same child hears his mother say to him, " You
swing your head too much ; it will strike the table." He
says, in a curious and surprised way, " Your head will strike
the table ?" Your again has received too large a sense ; he must
be taught to reduce it to mean the head only of the person
he is speaking to. The process of checking goes on; new
experiences will complete the tendency which produced the
word white, and once accomplished, it will correspond not
only to the presence of bright fresh colour, but, more than
this, to the presence of a particular colour. Similarly,
and by another series of experiences, the tendency which
produced the word your when given definite precision,
will correspond not only to possession, but also to this
supplementary circumstance, that the thing possessed
belongs to the person spoken to. Such is the history of
language : we experience spontaneously, after having come
in contact with a series of similar objects, a tendency which
corresponds to what there is in common to these objects ;
that is to say, to some general character, to some abstract
quality, to an extract from the objects, and this tendency
results in a gesture, in some mimicry, in some distinct sign,
which in maturity becomes a name.
Herein consists the superiority of the human intelligence.
Very general characters arouse in it distinct tendencies ; in
other words, very slight resemblances between different
objects are sufficient to excite in us a name or special de-
signation; a child succeeds here without effort, and the
genius of well-endowed races, as that of great men, and
notably of inventors, consists in observing resemblances
more or less delicate and novel; that is, in feeling arise in
them, at the sight of objects, certain slight and delicate ten-
dencies, and consequently, distinct names, which correspond
to shades imperceptible to ordinary minds, to the very
c 2
20 OF SIGNS, [BcoK I.
slight characters hidden beneath a heap of the coarse,
striking circumstances, alone capable, when the mind is
ordinary, of leaving an impression upon it, and having a
response in it. This aptitude once established, the rest
follows. By the accumulation and contrariety of daily
experiences, tendencies and names multiply, are circum-
scribed, and become subordinated, like the general qualities
they represent ; and the hierarchy of things is translated
and repeated within us by the hierarchy of tendencies and
names.
VI. On the other hand, if we may use the expression,
names fill out. In proportion as our experiences become
more numerous, we remark and consequently name a
greater number of general characters in the same object.
Its name, which at first denoted the single character
which struck us at first sight, now denotes several others.
It now corresponds, not to an abstract quality, but to a
group of abstract qualities ; it was only general, it becomes
collective.
Take any animal, a cat, for instance. As all cats have
points of strong resemblance, and differ a good deal from
our other animals, we have no difficulty in learning their
common name, and observing their common characteristics.
In other words, this name corresponds to a certain. distinct
form, at rest or moving, sleeping in a stable, or creeping
cautiously along a roof. This is the common popular sense,
and the tendency which results in the name corresponds to
little more than this. But a naturalist takes me, and open-
ing a cat, shows me the pouch we call the stomach, the little
vessels we call veins and arteries, with their infinite rami-
fications ; the collection of smooth tubes which are the intes-
tines, and the bars, arches, frames, cavities, and hinges, which,
with their connections, make up the skeleton. I might
remain for six months continually seeing new things. If I
were to work with a microscope, my life would not be long
enough, and, speaking accurately, no life or series of lives
would suffice ; beyond the observed properties, there will
always remain others unobserved, the unlimited matter of
CHAP. II.] GENERAL IDEAS AND SIMPLE SUBSTITUTION. 21
an unlimited science. Henceforward the name corre-
sponds for me, not merely to the experience of a certain
external form, but also to that of a certain internal
structure, that is, to an enormous number of various phe-
nomena which I have experienced, and to an indefinite
number which I might experience. If I have paid suffi-
cient attention to the internal structure, I shall pronounce
the word cat as confidently when I see the blanched
skeleton, as at the sight of the living furry body. The
second experience now results in the same name as the first.
Two distinct tendencies coincide therefore in the same
effect. The name has become the equivalent of the cha-
racters common to the different skeletons of the kind, as
of the characters common to the different living animals
of the kind; its presence, which once aroused images only of
certain velvety, living, bounding forms, now arouses also
images of certain bony lifeless frameworks. It may arouse
many other images, those of all the mechanical, phy-
sical, chemical, anatomical, vital, moral peculiarities which
naturalists and moralists can discover in the race of cats ;
it assembles them all in itself, together with the names we
denote them by; it is the substitute of the whole band. On
hearing the name cat, we can substitute for it a definition
or a description that is to say, replace it either by the two
principal names which determine its rank in the classification
of animals, or by the names of all the characters which our
, experiences have discovered in it, and consequently, recal
more or less vividly to our minds, the likenesses of such ex-
periences. Henceforth, the couple whose first term is the
name, comprises, as second term, an immense list of other
words, and consequently, as great a series of distinct ten-
dencies, which correspond to general characters equally
distinct, and leave room beside them for an infinite number
of new tendencies which experience may excite. Such is
the power of the substitution established by couples. Two
terms being the equivalents of one another, the first, which
is so simple, so manageable, so easy to recal, is capable of
replacing the second, even when the second is an immense
22
OF SIGNS.
[BOOK I.
army, whose lists always open, await and are continually
receiving new soldiers.
The reader sees at once that in place of the name cat
we might put that of dog, monkey, crab; or of any animal or
plant whatever ; or again, that of any group, animal or vege-
table, as extensive or as narrow as we please, and, in general,
of any group, moral or physical. The operation would be
similar; all general names acquire extensions of meaning
in the same way. Arranged in relation to one another, each
with its retinue of tendencies, they make up the principal
furniture of a thinking brain. By the side of continual
experiences and reviving images, there are names which we
term ideas ; all of them mental representatives of abstract
characters and general qualities, each one called up by some
distinct tendency, all incessantly extended by new tenden-
cies, gaining precision in their application, and increased in
their contents by the daily progress of discovery, which,
adding to their meanings, limits their application.
CHAP. III.] GENERAL IDEAS A XD REPEATED SUBSTITUTIONS. 23
CHAPTER III.
OF GENERAL IDEAS AND REPEATED SUBSTITUTIONS.
I. THERE are things of which we can have no experience ;
now, since experiences are what, by their common character,
arouse in us a distinct tendency and the name which we
term an idea, it seems as if we could never attain to ideas
of such things. We have, nevertheless, very clear and exact
ideas of them. The operation, which consists in giving
names to things, becomes complicated, and leads us by a
circuit to unhoped-for successes. The same instrument is
at work as before, but it works by a series of substitutions,
instead of a simple substitution.
Consider the first number that comes to hand : 36, for
example. When I read this sign, I thoroughly understand
its sense ; that is, I clearly imagine what it replaces. 36
is by definition 35 plus 1. In other words, the group we
call 36 is the same as that which we call 35, if to 35 we add
1. 36, then, is a collective term which replaces two others.
But 35, by definition, is 34 plus 1 ; 34, again, is 33 plus 1 ;
and so on. 36, then, in final analysis, is an abbreviatory
expression which replaces thirty-six others. Let us go back
to the elements, the better to understand this operation.
Suppose a red counter at one corner of the table, and a
white one at another. I may neglect all their respective
qualities, and be struck solely with the fact that a part of
my impression is repeated, and feel that what I have just
experienced in the case of the red counter is, up to a
certain point, similar to what has happened in the case of
the white, and after the two several experiences, may feel a
24 OF SIGNS. [BOOK I.
distinct consecutive tendency, corresponding to their num-
ber, that is, to the property they have of being two. This,
like all other tendencies, results in a sign ; let us take
for this sign the ordinary word, two. Here is a general
name; we shall be inclined to pronounce it, as in the
case of the counters, after each repeated experience.
Similarly, too, when we read it or hear it, we have only
to dwell on it to call up inwardly, as with the word cat or
birch-tree, an image of a case to which it is applicable;
we think of a counter beside a counter, a stone beside
a stone, a sound followed by a sound, as just now we
imagined a tapering face with white or grey fur, a slender
white trunk with small quivering leaves. The same is
the case with the words, three, four ; it is more difficult
with the words, five, six ; the difficulty increases with the
higher numbers, and there is always a figure, larger or
smaller, at which the mind stops ; we cannot perceive or
represent distinctly to ourselves as a whole, more than
a certain number of facts or objects; generally five or six,
more often four. To remedy this inconvenience we neglect
the group corresponding to the word, and fix our whole at-
tention on the word we have substituted for it ; after seeing
four objects together we forget them, and think only of
the word four, and this is allowable, since when later on we
return to the word and consider it, we shall see the objects
again in our minds without mistake or confusion. Here
then we have four operations replaced by one only. When
a new object, similar to the foregoing ones, is met with after
we have pronounced the word four, it will form, with the
word, a new group, and will excite in us a tendency
analogous to that which made us use the word two a ten-
dency similar to the first from its involving an addition,
differing from the first from its being an addition, not of
one object to another, but of an object to a group of four
objects. This new tendency results in a new name, five.
Another, excited by this previous one, will result in the
word six, and so on. We see that in this scale each
new name is the substitute of the preceding one, and
CHAP. III.] GENERAL IDEAS AND REPEATED SUBSTITUTIONS. 25
consequently of the object of the preceding one joined to
unity.
Here, again, an insurmountable difficulty has been evaded.
If we can imagine distinctly as a whole two, three, or even
four objects, we cannot do so with respect to 36 as a whole.
The abstract and general property of being two, three, or
four, may arouse in us a tendency, and consequently a
corresponding name; on the other hand, the general and
abstract property of being 36, or any other considerable
number, cannot do this. Before an obstacle like this we
must proceed indirectly; we bridge over the ditch too wide
for our legs. We no longer replace at once by a word the
general and abstract character of the group in question;
for experience cannot successfully attain to such a group.
Thirty-six pawns on a chess-board give an impression only
of a mass and a whole, without distinct numerical know-
ledge of the individuals. We proceed more slowly; we
first take a very small group, proportioned to the limited
range of our minds, and capable of arousing in us a ten-
dency and a name. We next join this name, and con-
sequently the object of the name, that is, the little group,
to a new individual, and this arouses in us another ten-
dency and another name; and thus step by step we
journey on to the final name, and this once obtained, cor-
responds to the abstract character which did not directly
arouse a name.
In this respect the final name is very remarkable. If
we look for its sense we find a name only, that of the lower
figure to which we add unity ; the same thing happens with
this lower figure, and so on ; it is only at the end of this
retracement of our steps, when we have descended some 30,
50, 100, 1000, or 10,000 stories, that we arrive again at our
experience. And yet this name replaces an experience,
another experience which we have not attained, which we
cannot attain, which is above man's powers, but which is
in itself possible, and which a more comprehensive mind
might attain to : 36 denotes the quality common to all
groups of 36 individuals; a quality which, as presented to
26 OF SIGNS. [BOOK I.
us, does not excite any precise tendency, and which a mind
capable of representing before it at once 36 objects or facts
in a distinct state, would alone experience. By this artifice,
we attain the same results as creatures endowed with imagi-
nations and memories far more clear and vast than our
own. Here, as before, all has been effected by substitu-
tion. After having enabled us to arrive at abstract qualities,
she affords us the means of counting and measuring quan-
tities. Thanks to substitutions, we were enabled to con-
ceive the abstract qualities of individuals. Thanks to a
series of repeated substitutions, we are able to name, and
consequently to conceive, certain abstract properties peculiar
to groups properties which the natural limitation of our
imagination and memory seemed to hinder us from ever
conceiving, that is to say, from naming.
II. The efficiency of substitution extends far beyond this.
As the reader knows, geometrical objects do not exist in
natiire. We do not meet, and probably can never meet,
with perfect circles, cubes, and spheres. Those we see or
construct are but approximately so. Nevertheless, we con-
ceive them as perfect ; we reason about figures of absolute
regularity. We know, with complete certainty, what is the
obtuseness of each angle in a regular myriagon, and to
how many right angles the whole of its angles taken to-
gether amount. Besides this, when for the better appre-
hension of a geometrical theorem we construct a diagram
on paper, we trouble ourselves very little as to its perfect
proportions ; we admit without difficulty shaky lines in our
polygon, and irregular curvature in our circle. In fact, we
do not consider the circle traced on the paper -, it is not the
object, but the aid of our thought; by its means we con-
ceive something differing from it, which is neither black
nor traced on a white ground, nor of any particular radius,
nor of unequal curvature. What, then, is this object we
conceive, and of which experience affords us no model?
The definition tells us. A circle is a closed curve, all whose
points are equally distant from an internal point called the
centre. But what have we in this phrase? Nothing,
CHAP. III.] GENERAL IDEAS AND REPEATED SUBSTITUTIONS. 27
except a series of abstract words which denote the genus
of the figure,, and another series of abstract words which
denote the species of the figure,, the second being combined
with the first, as a condition added to a condition. In
other terms, an abstract character denoted by the first words
has been joined to an abstract character denoted by the
second words, and the total compound thus constructed
denotes a new thing to which our senses cannot attain,
which our experience cannot come in contact with, which
our imagination cannot trace. There is no necessity for
our attaining to, meeting with, or imagining this thing;
we have its formula, and that is enough.
In fact, this formula would be rigorously the same if
the object had fallen within our experience. We have
constructed the formula before instead of after the experi-
ence, and it corresponds all the more closely to the thing,
since the thing must bend to it not it to the thing. The
two then make up a couple whose second term, the defi-
nition, is equivalent to the first term, that is, to the object.
This object may remain ideal : it may itself be situated
.beyond our grasp ; it matters little ; we have its represen-
tative. Whatever properties and relations we find in
the substitute we shall safely ascribe to the thing for
which it is substituted. We arrive at this indirectly, as a
surveyor, who, wishing to measure an inaccessible line,
measures a base and two angles, and knows the first quan-
tity by the three second. In this way all mathematical con-
ceptions are formed. We take very simple abstractions, the
surface which is the limit of the solid, the line which is the
limit of the surface, the point which is the limit of the line,
the unit or quality of being one, that is to say, distinct ex-
istence among similar things. We combine these terms to-
gether and form, first, compounds of small complexity, those
of two, three, four, and the earlier numbers, those of plus
and minus, of greater and less, of longer and shorter lines ;
then those of straight line and curve, of triangle, of circle ;
then, those of sphere, cone, cylinder, and the rest. The
complication of compounds goes on increasing ; it is un-
28 OF SIGNS. [BOOK I.
limited. Taken together they form a kingdom apart of
objects which have no real existence, but which are capable,
like real objects, of being classed in families, genera, species,
and properties, of which we discover by considering in their
place the properties of the formulae which we substitute
for them.
By a strange continuation the process which has formed
these objects is also that which establishes their relations.
Arithmetic, algebra, geometry, analytical geometry, me-
chanics, the higher calculus, all the propositions of
mathematical science, are substitutions. Any number we
take is a substitute for the preceding number added to
unity. To calculate, is to replace several numbers by a
single one at the end of several partial replacements.
To solve an equation, is to substitute terms for other
terms with the object of arriving at a final substitution.
To measure, is to replace an undetermined magnitude by
another magnitude defined in its relation to unity. To
construct a diagram for the demonstration of a theorem
is to substitute certain known lines and angles for other
lines and angles which it is required to know. To find
the algebraic formula of a curve, is to discover a mathe-
matical relation between certain lines which are connected
with the curve, and to translate quality into quantity.
However we may reason about numbers and magnitudes,
the process amounts to passing from one equivalent to
another equivalent by the aid of a series of intermediate
equivalents, to replacing magnitudes by numbers ex-
pressing them, a figure by a corresponding equation, a
complete quantity by a quantity in process of completion,
having the first as limit, movements and forces by lines
representing them. We pass from each province to the
other by substitutions, and, as a substitute may have
substitutes, the operation has no limits.
III. Leaving for the moment this extension of our pro-
cess, let us consider it once more at its outset. We have
seen how, by combining abstracts, we construct the first terms
of couples, the second terms of which are beyond our reach,
CHAP. III.] GENERAL IDEAS AND REPEATED SUBSTITUTIONS. 29
and how, by the study of the generating formula, we dis-
cover the properties of the object engendered by it. In
certain cases, we discover in it wonderful properties, and
the formula makes known to us facts situated not only
beyond our experience, but beyond all experience. If we
divide 2 by 3, we find an infinite decimal fraction, 0*6666
&c., and we can prove that it is infinite. It is strictly so,
and without possible break ; however far we may prolong the
operation, the remainder will always be 2 and the quotient
always 6. After a million, after a thousand million, after
a million million of such divisions, new terms will pre-
sent themselves, with the same remainder and the same
quotient, with a total quotient always too small, too small
by a fraction with 2 for numerator, and for denominator
unity followed by as many zeros as there are units in the
number of divisions we have made. Here is something in-
finite ; not vague, not indefinite, but precise, which is ex-
pressly opposed to any limit, and so clearly conceived that
all its elements have their distinct and express properties.
Does this mean that I perceive distinctly the infinite series
of these elements ? Certainly not. Here again, there is a
substitute, the formula, from which the series and the
properties of its elements are derived. What we perceive,
is a general character of the dividend and remainder.
After the first division we can see that, the remainder
being 2 like the dividend, must, in becoming in its turn a
dividend, give rise again to a remainder 2, which in its
turn will do the same, and so on. In other words, we
discover in the dividend this property of giving rise to a
similar figure, which, being similar to it, has the same
property as it. This abstract quality is the cause of the
whole series; it forces it to be infinite, it alone is
what we perceive ; when we say that we conceive an in-
finite series, it only means that we discover this property
of inexhaustible regeneration ; all we seize is the generating
law; we do not embrace all the engendered terms. But
as far as we are concerned the effect is the same ; for by
applying the law we are able to define whatever term we
30 OF SIGNS. [BOOK I.
please of the series, to measure exactly the increase of ap-
proximation it brings to the quotient,, to calculate strictly
the degree of error which the division would include were we
to stop here. The perception of the law is equivalent to the
perception of the series ; an infinite line of distinct terms
finds its substitute in an abstract character, and, in place
of an experience which is by definition impossible, we have
disengaged a property whose isolation has only required
two experiences, and which is of equal value to us.
And so it happens, whenever we conceive and affirm
some really infinite abstract magnitude, time, or space.
We take a fragment, some short portion of the duration
comprised in our successive sensations, some narrow portion
of space comprised in our simultaneous sensations. We
consider this fragment apart ; we extract from it this pro-
perty it has of being over-extended by a border absolutely
similar to itself. We lay down, as before, a general law
that the magnitude in question is continued beyond itself by
another wholly similar magnitude, and this by another, and so
on, without the possible intervention of a limit. Our concep-
tion of infinite time and infinite space is reduced to this.
But the result is the same as if the field of our imagina-
tion were infinitely extended and capable of setting before
us at a glance the whole infinite succession we call time,
or the extension, infinite in three directions, which we call
space. For starting from the general character which
alone is present to our minds, we are able to imagine any
portion of time or space as clearly, and to affirm of it as
surely, as if we had experience of it ; no matter what the
portion be, whether a fragment of duration preceding
the solar system, or a portion of space beyond the furthest
nebulae of Herschel. It is possible, then, to represent in-
finite objects, series, or quantities,* by an abstract property.
It is enough if this is their generator. By it, indirectly,
they become present. Here we have, I think, the most
* When we speak of an infinite quantity, it is by extension ; strictly speaking,
quantity is always finite, and there is nothing infinite but series.
CHAP. III.] GENERAL IDEAS AND REPEATED SUBSTITUTIONS. 31
extraordinary example of substitution. There are other
cases,, analogous but reversed, in mathematics ; certain
quantities, which go on increasing or decreasing, without
the possibility of a limit, replace the limit which they
necessarily approach without ever touching it. A polygon
with an infinite number of sides inscribed in a circle
is equivalent to the circle. The fractional number 1+J-f J
+ j- &c., is equivalent to the number 2. Here again, as
before, mathematicians do but resume, extend, or reverse
a spontaneous process of the mind. The process is ex-
plainable similarly, whether direct or reversed. Given two
members of a couple, one infinite, the other limited, we
can consider at will the one or the other, and if they corre-
spond strictly, can discover in the one properties belonging
also to the other, but not discoverable in it.
IV. To recapitulate. We do not conceive numbers, with
the exception of the three or four earlier ones, but their
equivalents, that is to say, the name of the preceding num-
ber joined to unity ; we do not conceive infinite or ideal
objects, but the abstract characters which generate them;
we do not conceive abstract characters, but the common
names which correspond to them. However far we may go,
we always come back to names. Things the most removed
from our experience and the most inaccessible to all ex-
perience, seem present to us ; what is actually present, in
such a case, is a name, the substitute of an abstract cha-
racter which is itself the substitute of the thing, and this
often only through many intermediate stages, till at last
by a series of equivalents the chain re-touches the distant
object which we cannot directly reach.
Hence arise singular illusions. We believe that, in ad-
dition to our general words, we possess general ideas ;
we distinguish the idea from the word ; it seems to us
something apart from the word, and to which the
word is merely auxiliary; we compare it with the image,
and pronounce them to fulfil similar offices in distinct pro-
vinces, and that ideas bring present to us general things,
as images bring present individuals. We remark with
32 OF SIGNS. [BOOK T.
Descartes, that we can readily conceive a myriagon
but have great difficulty in imagining it. We set on one
side the intelligible myriagon and the corresponding
precise idea, and, in contrast, the actual myriagon and the
corresponding confused image. We then observe that this
idea is in no way similar to the image, except in its employ-
ment ; it brings before us an absent thing as the image
does, but that is all. It has no other properties ; it is not,
like the image, an echo, the echo of a sound, a smell, a colour,
a muscular impression, in short, the internal revival of
some sensation ; there is nothing sensible about it, and
we can only define it by denying of it all sensible qualities ;
it seems then a pure activity stripped of all other qualities
but that of bringing the myriagon present to our minds.
We compare it to something intangible, unextended, in-
corporeal ; we suppose a being as pure and ethereal as itself
of which it is the manifestation ; we call it mind, and say
that, irrespective of images, our mind knows and deals
with abstract qualities of things.
The mechanism of this illusion may now be readily de-
tected. We have overlooked the word which is the whole
substance of our operation ; we have treated it as accessory
and have considered the operation, omitting what it com-
prises ; hence a blank. This error of consciousness is of fre-
quent occurrence and may be traced to a general law.
When an impression, or group of impressions, is many times
repeated, our attention ends by fixing itself entirely on
the interesting and useful part ; we neglect the rest, we
cease to notice it, we become unconscious of it, and though
present, it seems to be absent. So it is, for instance,
with the slight muscular sensations occasioned by the eye
adapting itself to various distances ; they are the signs of
these distances, and by them we determine the degree of
proximity or distance of objects. We necessarily have
these sensations when we judge of distances, but we cannot
detect them, even if we wish to. To us, they are as if they
did not exist ; we appear to know directly, and without their
aid, the positions which they alone denote; if ever they
CHAP, in.] GENERAL IDEAS AND REPEATED SUBSTITUTIONS. 33
strike us, it is in extreme cases, as when we attempt to read
something at a distance, or inconveniently near the eye, and
feel sensible fatigue in the muscles ; except in such cases they
are invisible, and have, as it were, vanished. So again, a
composer who has just read some air of an opera, does not
recall the crotchets, quavers, keys, staves, and all the black
hieroglyphics over which his eyes have passed, but only the
series of chords which he has heard mentally ; the signs are
obliterated, the sounds alone survive. When words are in
question, we can trace the different degrees of this oblitera-
tion. The meaning of a page in manuscript is compre-
hended with far more difficulty than that of a printed one ;
our attention is partly attracted by the external form of
the characters, in place of attaching itself solely to the
sense they bear ; we observe the individual peculiarities of
the signs, as well as what they are employed to represent.
But after a while, these peculiarities cease to strike us ;
when they are no longer new, they are no longer singular,
and no longer singular, are no longer observed ; and then,
in the manuscript as in print, we seem no longer to be
following words, but pure ideas. We see now how it
necessarily happens, that in our reasonings, and all the
higher operations of the mind, the word, though present,
is unperceived. From the train of our discoveries we
conclude that we have acted, and produced a series of
acts, that this series corresponds to a series of qualities,
or characters of things, that our activity is effective, and
therefore real. What then can we affirm of this internal
activity ? Nothing, except that it is activity ; by the dis-
appearance of words we have exhausted it of all it comprises ;
we set it apart pure and simple, or as we say, spiritual ;
having stripped it, we believe it to be naked ; and when,
later on, we observe that to produce it we have made use
of signs, we conclude that the sign is but a preliminary aid
to it, and a distinct reminder of it. This separation and
nudity are of our own effecting ; they do not belong to it,
but are lent it by us.
This is the first of psychological illusions, and what we
D
34 OF SIGNS. [BOOK I.
term consciousness swarms with such. The false theories
they have given rise to are as complex as they are many,
and are at present obstructing science. When they are
cleared away, science will become simple again. Having
discarded this illusion, we see the consequences. What
we have in our minds when we conceive general quali-
ties and characters of things, are signs and signs only.
I mean certain images or revivals of sensations of the eye
or ear, wholly similar to other images, except in their cor-
responding to characters and general qualities of things,
and in their replacing the absent or impossible perception
of these characters and qualities. Thus when, neglecting
present sensations, we observe the never-resting inmates of
our mind, we find there images only, some prominent ones
which strike the attention, others faded, and seemingly
worn away to shadows, on account of the attention being
diverted from them to their uses. Here we have an element
of knowledge which seemed primitive, but which is reduced
to another. We must now attempt to know that other.
Since our ideas may be reduced to images, their laws may
be reduced to laws of images; images then are what we
must study.
CHAP, i.] THE NATURE AND REDUCTION OF IMAGES. 35
BOOK II.
OF IMAGES.
CHAPTER I.
OF THE NATURE AND REDUCTION OF IMAGES.
I. YESTERDAY evening,* about five, I was on the quay
by the Arsenal, watching in front of me, across the Seine,
the sky reddened by the setting sun. Fleecy clouds rose
in the form of a half dome, and bent over the trees of the
Jardin des Plantes. The whole of this vault seemed en-
crusted with scales of copper ; countless indentations, some
almost burning, some nearly black, extended, in rows of
strange metallic lustre, up to the highest part of the sky,
while, all below, a long bronze-coloured band, extending
along the horizon, was streaked and cut by a black fringe
of branches. Here and there, rose-coloured gleams of light
rested on the pavements ; the river shone softly through a
rising mist; I could see barges floating with the stream,
and two or three teams of horses on the bank, while towards
the east, the slanting beams of a crane stood out against the
grey sky. In half an hour, all this had died out; there
was but one patch of clear sky behind the Pantheon ; red-
dish-coloured smoke was wreathing about in the dying
purple of the evening, and the vague colours intermingled.
A blue vapour hid the arches of the bridges and the edges
of the roofs. The apse of the cathedral stood alone, looking
with its pinnacles and jointed buttresses, in size and shape
like an empty crab-shell. Things prominent and coloured but
* 24th November, 1867.
36 OF IMA GES. [BOOK II.
a moment ago, were now like mere sketches on a dull paper.
Here and there a gas-light shone out like a lonely star, and
caught the attention as other things faded away. Soon,
strings of light extended themselves as far as the eye could
reach, and the indistinct nickering glare of crowded Paris
rose in the west ; while below the arches, along the quays,
and over the weirs, the rippling water kept up its nightly
murmuring.
I saw this yesterday ; and now as I write I see it again
dimly, it is true, but still I see it. The colours, forms,
sounds, which struck me yesterday, are now renewed, or
nearly so. Yesterday, I experienced sensations excited by
the immediate contact of things and immediate action of
the nerves. To-day, impressions analogous to those sen-
sations, though remotely so, arise in me, notwithstanding
the want of this action and contact, notwithstanding the
presence of other actions and contacts. It is a semi-
revival of my experience; different terms might be used
to express it, we might call it an after-taste, an echo,
a representation, a phantom, an image of the primitive
sensation ; it matters little ; all these comparisons mean
no more than that after a sensation excited by the outer
world, and not spontaneous, we find within us a second
event corresponding to it, which is spontaneous and is not
excited by the outer world, which resembles the sensation,
and is accompanied, though not so forcibly, with the same
emotions, which is pleasurable or the reverse, but in a less
degree, and is followed by some, but not all, the same mental
conclusions. The sensation repeats itself, though with less
distinctness and force, and deprived of many of its sur-
roundings.
This obliteration is more or less complete according to
the differences of men's minds, and this is what we mean
when we say that men have more or less memory. Again,
it is more or less complete in the same minds according to
the different kinds of sensations, and this is what is meant
by saying that such a man remembers forms, another colours,
another sounds. For example, in my own case, I have but
CHAP. I.] THE NATURE AND REDUCTION OF IMAGES. 37
an ordinary memory for forms and a slightly better one for
colours. I can see without difficulty after several years five
or six fragments of an object, but not its precise and com-
plete outline ; I can recall more easily the whiteness of a
sandy path at Fontainebleau, the hundred little spots and
stripes made by the sprigs of wood strewed on it, its winding
curves, the faintly rose-coloured tints of the heather by its
sides, the wretched appearance of a stunted birch clinging
to the side of a rock ; but I cannot trace in my mind the
winding of the path or the jutting out of the rocks : if I
mentally catch sight of the swelling of some vegetable muscle
my half-sight stops there ; above, below, all is vague ; even
involuntary revivals, which are the most vivid, are only half
clear to me; the most visible and most highly coloured
fragment is dull and tame. Compared to the sensation it
is as a half-heard whisper to an articulate, ringing voice.
In my case, all that is reproduced uninjured and whole is
the precise shade of emotion, harsh, tender, strange, sweet,
or sad, which followed or accompanied the external corporeal
sensation. I can thus renew my pains and pleasures, the
most complex and most delicate, with extreme exactness and
after considerable distances of time. In this respect, the
incomplete and failing whisper has almost the same effect as
the voice. But if, instead of taking the instance of a man
inclined to pay principal attention to sentiments, we look
at men accustomed to observe particular colours and forms,
we shall find cases of images so clear as to differ little from
sensations.
For example, children accustomed to calculate in their
heads, write mentally with chalk on an imaginary board the
figures in question, then all their partial operations, then
the final sum, so that they see internally the different lines
of white figures with which they are concerned. The re-
markable children who are precocious mathematicians give
a similar account of themselves.* Young Colborn, who
had never been at school, and did not know how to read or
Gall, " Fonctions du Cerveau," tome v. 130.
38 OF IMAGES. [BOOK II.
write,, said that when making his calculations, "he saw
them clearly before him." Another said that he " saw
the numbers he was working with as if they had been
written on a slate." So again, we find chess-players who
play a game with their eyes closed, and faces turned
towards the wall. They have numbered the squares and
pieces ; at each move of their opponent they are told the
piece moved and the new square it occupies ; they give
directions themselves for the movement of their own
pieces, and go on in this way for many hours. They often
win, even when opposed to skilful players. Evidently the
figure of the whole chess-board, with the different pieces in
order, presents itself to them at each move, as in an in-
ternal mirror, for without this they would be unable to fore-
see the probable consequences of their adversary's and their
own moves.
An American friend of mine, who has this faculty, de-
scribes it to me in these words : " When I am in my
corner, facing the wall, I see simultaneously the chess-board
and all the pieces, as they were in reality after the last
move. And as each piece is moved, I see the whole chess-
board with the new change effected. If I am in doubt in my
mind as to the exact position of a piece, I play over, men-
tally, the whole game from the beginning, attending carefully
to the successive movements of that piece. It is far easier
to deceive me when I watch the board than otherwise ; in
fact, when I am in my corner, I defy any one to mislead
me as to the position of a piece without my afterwards
detecting it I see the piece, the square, and the
colour, exactly as the workman made them that is, I see
the chess-board standing before my adversary, or at all
events, I have an exact representation of it, and not that of
another chess-board. So far is this the case that, before
retiring to the corner, I begin by carefully looking at the
chess-board and men as they stand, and to this first impres-
sion I mentally attend and revert." Usually, he does not
see the table-cloth nor the shadows of the pieces, nor the
minute peculiarities of their make, but can recall them if he
CHAP. L] THE NATURE AND REDUCTION OF IMAGES. 39
wishes. He has often played chess with a friend who has
also this faculty, while walking along the quays or in the
streets. As might be expected, so exact and intense a
representation is repeated and lasts involuntarily. et I
have never played a game;" says he, "without having
played it over again four or five times in the night in bed,
with my head on the pillow When I am sleepless
and have unpleasant thoughts, I set myself to play at chess,
imagining a game, with all the pieces, and this occupies
my mind and drives away the besetting thoughts." The
first players are not the most skilful at this artifice. La-
bourdonnais could only play two games at once, mentally ;
having once attempted three at a time he died from the
effort. " It is not unusual to find in clubs, fourth-rate players
who wake up some morning with this faculty." Some of
them attain an extent and clearness of imagination which
are simply marvellous. " Paul Morphy plays eight games
at a time, and Paulsens twenty. This I have seen myself."
Other images, far more irregular and with more variety of
shade, and so, it would seem, more difficult to recall, present
themselves with equal precision. Certain painters, draughts-
men, and sculptors, after attentively considering a figure,
are able to draw it from memory. Gustave Dore has this
faculty ; Horace Vernet had it. Abercrombie* mentions a
painter who copied from recollection and without the
aid of an engraving, a Martyrdom of Saint Peter, by
Rubens, with so perfect an imitation that the two
pictures, being placed beside one another, considerable
attention was required to distinguish the copy from the
original.
We can follow the different stages by which the ordi-
nary image passes to this height of clearness and detail. In
a school of art at Paris, the pupils were practised in copying
models from memory. After four months' practice they
said that " the image " had become " much more distinct,
16 "Inquiries concerning the Intellectual Powers," p. 126 ; and see Brierre de
Boismont, " Des Hallucinations," pp. 449 et seq., 26 et seq., where many analogous
cases are collected. See also " Anuales Medico-Psychologiques," 3 me Serie.ii. 295
40 OF IMAGES. [BOOK II.
and if it disappears they can recall it almost at will."
M. Brierre de Boismont,* having studiously impressed on his
mind the figure of a priest of his acquaintance, says, " At
present this mental representation is visible to me, whether
my eyes be shut or open/' The image appeared to him
" external," placed in front of him " in the direction of the
visual ray It has the size and characters of the ori-
ginal ; I can distinguish his features, the cut of his hair, the
expression of his face, his dress, and all the details of his
person. I see him smile, speak, preach ; I mark even his
habitual gestures The image is shadowy and of a dif-
ferent nature from the objective sensation but clearly
outlined and coloured," and, saving this distinction of nature,
provided with all the characters belonging to the real person,
or, more precisely, with all the characters which belong to
the sensation experienced in the presence of the real person.
We may confidently assert then, that the internal event, which
we call a sensation, and which is produced in us when our
nerves, and consequently our brain, receive an impression
from without, is reproduced in us without impression from
without in the majority of cases partially, feebly, and
vaguely, but in many cases with greater clearness and force ;
in some cases with a precision and detail nearly equivalent
to what we find in the sensation.
The sensations of hearing, of taste, of smell, of touch,
and, in general, all sensations, whatever be the nerve by
whose action they are excited, have their images. We
can all of us hear tunes mentally, and in some cases the
image is not far removed from the sensation. Just now,
thinking over a representation of the " Prophete," I re-
peated silently to myself the pastorale from the overture,
and followed, I venture to say almost felt, not only the
order of the notes, their different height, rests, and lengths,
not only the musical phrase repeated as an echo, but also
the keen, piercing tone of the hautboy which plays it ; its
* Op. cit. 449 ; and De Boisbaudran, " Education de la Memoire Pittoresque,'
pp. 77 and 83.
CHAP. L] THE NATURE AND REDUCTION OF IMAGES. 41
sharp drawn-out notes of so rustic a harshness that the
nerves are startled, and filled with a rough pleasure, as at the
taste of raw wine. Every good musician experiences this
sensation at will, when he follows the lines of music covered
with their black marks. The leader of an orchestra/* ques-
tioned by M. Buchez, told him that when he looked over a
score " he heard as in his ear" not only the chords and
their succession, but also the tone of the instruments. On
the first reading over, he distinguished the quartet ; at the
second and succeeding ones, he added to the quartet the other
instruments ; and finally he perceived and appreciated dis-
tinctly the effect of the whole. Great musicians have this
gift of internal hearing in an eminent degree. It is well
known that Mozart, having twice heard the Miserere of the
Sistine Chapel, wrote it down entirely from memory. As
it was forbidden to copy it, the fidelity of the master of
the chapel was suspected, on account of the difficulty of
the exploit. f Mozart, no doubt, on his return home, found
in his mind, when seated at his table, as if in a minutely
exact echo, these lamentations composed of so many parts
and carried over a series of notes so strange and deli-
cate. When Beethoven composed many of his great works
after he had become completely deaf, the combinations of
notes and tones which we now admire in them were pre-
sent to him. They were necessarily present, since he
measured their effect beforehand, and measured it with
rigorous precision.
II. This close resemblance of the image and sensation
becomes clearer still if we consider the circumstances under
which the higher degrees of intensity of the image occur.
A first excitant is the extreme nearness of the sensation.
When we have heard a full striking tone, for example, the
rich prolonged note of the violoncello, clarionet, or horn, if
the sound suddenly ceases, we continue for some seconds
* Brierre de Boismont, op. cit. 459.
f It is necessary to have heard this Miserere, to appreciate the capacity and
precision of such memory for music.
42 OF IMAGES. [BOOK II.
to hear it mentally; and, though at the end of these
seconds its image becomes feeble and obscure, we con-
tinue, if we derived any pleasure from it, to repeat it
internally with remarkable fidelity, and without letting
go any portion scarcely of smooth or striking sound.
And so, when we shut our eyes after having regarded
attentively any object, a figure in a print, the back of
a book in a library, the perception, which has become in-
ternal, continues for nearly a second, then disappears, then
renews itself, but softened; then is troubled and fails
utterly, without leaving any other trace than a vague out-
line ; and the losses which the image has undergone prove
by their contrast the force it had to commence with. So it
is after a smell, a taste, an impression of cold, of heat, of
local pain, and the rest. If the sensation, instead of pre-
ceding, is about to follow, the effect is the same. A gour-
mand seated before a savoury dish, the steam of which is
rising under his nose, and into which he has already put his
fork, tastes beforehand its exquisite flavour, and the glands
of his tongue become moistened; the image of the ex-
pected flavour is equivalent to the sensation of the actual
flavour ; the resemblance is carried so far that the salivary
glands are equally excited in either case. This is why a
physiologist, who wishes to obtain a quantity of saliva to
experiment with, ties up a hungry dog a few inches from
a piece of meat, and collects the liquid which the flavour
continually wished for and continually absent discharges
from the animal's jaws. So by an analogous but contrary
effect, anything unpleasant we are obliged to take excites
vomiting by the simple thought of its taste before it
touches our lips. So again, a ticklish person whom we
threaten to tickle, and who sees our hand approaching,
imagines so strongly the coming sensation, that he has
spasmodic feelings, the same feelings, in fact, as if the sen-
sation had taken place. Many persons who are about to
undergo a surgical operation, feel beforehand the shooting
pain which will follow the first cut, and sweat and grow
pale at the very thought, and sometimes suffer as keenly
I
CHAP. I.] THE NATURE AND REDUCTION OF IMAGES. 43
as when under the saw and knife. A lady"* who thought
she was inhaling nitrous oxide, and who had simply a bottle
of common atmospheric air under her nose, fell in a fainting
fit. These examples show us also that the importance of the
sensation is another excitant as powerful to strengthen the
image as the proximity of the sensation. A traveller in
Abyssiniaf saw one of his men torn by a lion ; many years
afterwards, when he thought of the circumstance, he could
hear mentally the cries of the unhappy man, " and felt as
if a hot iron were entering his ear." Numbers of mysticsj
have represented to themselves the passion of oar Lord
with such force, that they have believed themselves to feel in
their bodies the rending and pain of the Saviour's wounds.
Every one knows the power of an image, especially when
strange and terrible, upon an excited and prepared mind :
it is mistaken for a sensation, and the illusion is complete.
Children, and even grown men, have fallen insensible
before a figure, or even a cloth, which they have be-
lieved to be a ghost. On recovering, they have asserted
that they saw flaming eyes, open jaws. In all these
cases the image has in no way differed, for the time at
least, from the corresponding sensation, and it is only
after the lapse of a longer or shorter time, when the re-
collection has subsided, and the circumstances have been
looked into, that the deceived person has recognised, his
mistake.
III. Hitherto we have seen the image approximating to
the sensation, acquiring the same clearness, the same
abundance of minute and circumstantial detail, the same
force, sometimes even the same persistence, furnishing the
same foundation for higher combinations and ulterior rea-
sonings, exciting the same impressions and same instinc-
tive actions, organic and muscular, having in short the same
properties, the same accompaniments, and same conse-
* Mueller, "Elements of Physiology," tr. Baly, ii. 1392.
f Brierre de Boismont, op. cit. 468.
I Maury, " La Magie et PAstrologie, &c.," 2 me partie, chap. iii. passim.
44 OF IMAGES. [BOOK II.
quents as the sensation, without, however, being wholly
and definitely confounded with it. In fact, there remains
a character which is distinctive to the image : we soon
recognise it as internal, we say to ourselves, at least
after a moment, that the thing thus seen or felt is but a
phantom; that our hearing, our sight, our taste, or our
smell, have experienced no real sensation. We are not
under the influence of hallucinations ; we do not say as
sick people sometimes do* " I saw and heard it as plainly
as I now see and hear you I assure you that
what I saw was as clear as the day ; and, if I doubt it, I
must also doubt that I see and hear you."
To explain so important a difference, we must observe
closely in what the recognition of an illusion consists.
There are two moments during the presence of the image ;
one affirmative, the other negative ; the second partially
qualifying what the first began to affirm. In the case of a
very precise and intense image, these two moments are
very distinct : at the first it seems external, situated at
such and such a distance from us, when a sound or visible
object is in question ; situated in our palate, nose, or
limbs, tvhen a sensation of smell, taste, local pain, or plea-
sure is in question. " The exercise both of conception
and imagination/' f says Dugald Stewart, " is always accom-
panied with a belief (at all events, momentary) that their
object exists There are few persons who can look
down from the battlement of a very high tower without
fear, while their reason convinces them that they are in no
more danger than when standing on the ground." In fact,
when we look directly down to the ground, we imagine our-
selves suddenly taken and thrown to the bottom ; and this
image alone is enough to make us shudder, since, for an
imperceptible instant, it has the force of a belief; we draw
back instinctively, as if we actually felt ourselves falling.
We must admit, then, that "whenever the objects of
* Baillarger, " Des Hallucinations," 374.
f "Philosophy of the Human Mind," chap. 3. i. 150-1. Ed. Hamilton.
CHAP. I.] THE NATURE AND REDUCTION OF IMAGES. 45
imagination engross the attention wholly, they produce a
temporary belief of their reality ." This is why persons who
experience very vivid images employ,, to describe them, the
same words as to denote the actual sensations ; and, during
some seconds, take their images for sensations. " I once
heard," says Lieber, et a coloured preacher describing the
torments of future punishment. He rose, not ineloquently,
from the description of one anguish to another, when at
last, carried away by uncontrollable excitement,, he merely
uttered, for more than a minute, a succession of inarticu-
late sounds or cries." * No doubt, during the minute in
question, his mental vision had all the characters of physical
vision. He had before him an imaginary hell resembling a
real hell, and he believed in his internal phantoms as in
real facts. " My imaginary persons," writes the clearest
and most accurate of modern novelists, " affect me, pursue
me, in fact, I live in them. When I was describing the
poisoning of Emma Bovary I had so strong a taste of
arsenic in my mouthy I was myself so far poisoned, that I
had two consecutive fits of indigestion, and real indigestion,
for I threw up my dinner."
An English painter, f whose rapidity of execution was
marvellous, explained his mode of work in this way :
" When a sitter came, I looked at him attentively for half
an hour, sketching from time to time on the canvas. I
wanted no more I put away my canvas, and took another
sitter. When I wished to resume my first portrait, / took
the man and sat him in the chair, where I saw him as dis-
tinctly as if he had been before me in his own proper person
I may almost say more vividly. I looked from time to time
at the imaginary figure, then worked with my pencil, then
referred to the countenance, and so on, just as I should
have done had the sitter been there when I looked at the
chair I saw the man. Gradually I began to lose the dis-
tinction between the imaginary figure and the real person;
* " Smithsonian Contributions to Knowledge," vol. ii. p. 9.
t Wigan, "A New View of Insanity. The Duality of the Mind, &c.," p. 124.
46 OF IMAGES. [BOOK II.
and sometimes disputed with sitters that they had been
with me the day before. At last I was sure of it ; and
then all is confusion I lost my senses, and was
thirty years in an asylum/'' When he left the asylum
he had still the power of painting a portrait from his in-
ternal image of the model, but was persuaded not to work,
for fear of a return of the madness.
The chess-player I have mentioned, writes again : " I never
think of distinguishing between my mental chess-board and
the actual one. As far as I am concerned, they are one ; and
I could only establish a distinction between them by an
effort of reasoning, the utility of which I have never expe-
rienced." Thus, while he is playing, his mental chess-
board stands to him in place of the actual one. In
other cases, morbid or quasi-morbid, we see the image
acquire complete and definite externality. " Recently,"
says M. Maury,"* " my eyes were attracted by a dish of
very scarlet cherries which were served at my table. Just
after dinner, the weather grew stormy, and the air very
close; I felt sleep coming over me, my eyes closed ; I was then
thinking of the cherries, and saw in a sleepy hallucination
these same scarlet cherries lying on the same green porce-
lain dish on which they had appeared at dessert. Here
was a direct transformation of my thought into sensation."
"Writers on insanity mention many instances of similar
transformations^ " A young man who suffered from epi-
lepsy, every fit of which was preceded by the apparition of
an indented wheel, with a horrible figure in the middle,
assured me that he had the power of producing hallucina-
tions. He amused himself by conceiving some strange
object to be present ; and scarcely had he formed it in
imagination before it appeared accurately before his eyes. I
have myself seen an instance of this kind in a monomaniac,
* ' ' Le Sommeil, et les reves," 240.
t "AnnalesMddico-Psychologiques," 3 me Serie, ii. 389-90, M. Michea Cases
collected by Abercrombie, M. Moreau, Maisonneuve, &c. See also, Baillarger
"Des Hallucinations," "Memoires de 1' Academic de Medecine," tome xii.
p. 250.
CHAP. I.] THE NATURE AND REDUCTION OF IMAGES. 47
a man of cultivated mind and perfect sincerity of character,
who assured me that he had but to recall to his mind or
to imagine a person or thing, for the person or thing to
appear at once before him with every appearance of exter-
nality."
There is no need to be ill or half asleep to watch the
metamorphosis by which the image projects itself from
within to an external position. " A friend of mine," says
Abercrombie,* " had been one day looking intensely at a
small print of the Virgin and Child, and had sat bending
over it for some time. On raising his head he was startled
by perceiving at the farther end of the apartment a female
figure of the size of life, with a child in her arms. The
first feeling of surprise having subsided, he instantly traced
the source of the illusion, and remarked that the figure
corresponded exactly with that which he had contemplated
in the print. The illusion continued distinct for about two
minutes/'f Goethe was able to produce in himself a com-
plete illusion at will. " When I closed my eyes," he says,
" and depressed my head, I could cause the image of a flower
to appear in the middle of the field of vision ; this flower
did not for a moment retain its first form, but unfolded
itself, and developed from its interior new flowers, formed
of coloured or sometimes green leaves. These were not
natural flowers, but of fantastic forms, although symme-
trical as the rosettes of sculptors. I was unable to fix any
one form, but the development of new flowers continued as
* Op. cit. p. 63.
t Griesinger, " Traite des Malades Mentales" (translation by Doumic), p. 104.
"Some observers are able to produce hallucinations at will; that is to say,
ideas existing in their consciousness, and on which they firmly direct their atten-
tion, call into play the sensorial functions. A person who suffered from halluci-
nations of hearing observed that he could produce the voices himself, and said after-
wards that this partly assisted him in recognising the error. M. Sandras speaks of
hallucinations he himself suffered from during an illness in which he mistook
his own thoughts and wishes for voices. These voices answered his mental ques-
tions as a person present would have done, but always in accordance with his
wishes.
"We consider the phenomena of imagination as among the functions of the in-
ternal sensorial apparatus, and as differing from its other functions in intensity
only."
48 OF IMAGES. [Boos II.
long as I desired it, without any variation in the rapidity
of the changes. The same thing occurred when I figured
to myself a variegated disk. The coloured figures upon it
underwent constant changes, which extended progressively,
from the centre towards the periphery, exactly like the
changes in the modern kaleidoscope." Finally, hallucina-
tions, that is to say, projections into the outer world of
simple mental images, have been produced, not only in full
health, but with the complete exercise, and, indeed, by the
exercise of the will. " A German writer on insanity, Dr.
Brosius, of Bendorf, mentions his having produced at will
his own figure, which stood before him for some seconds,
but which vanished immediately he attempted to fix his
mind on his personal existence."*
These extreme cases show by their exaggeration the
nature of the normal state. Just as by dissecting an hy-
pertrophied stomach we succeed in distinguishing disposi-
tions of the muscular fibres which are invisible in a healthy
stomach, so by examining prolonged illusions, which last
for seconds, minutes, or more, we discover the existence of
fugitive illusions, accompanying ordinary images, but so
rapid, short, and instantaneous, that we cannot isolate or
observe them directly. This illusion is none the less real,
and the simple analysis of the words we use to denote the
image bears witness to the double operation by which it is
formed. We say that such an image, a phantom of hear-
ing or sight, of taste or smell, which seems to be situated
either in some part of our organs, or without us, seems, er-
roneously, to be situated there, since it is not there or without
us, but internal. This phrase itself indicates the recognition
and correction of an error, therefore of a preliminary error ;
we must have been deceived for the moment, since, a moment
afterwards, we find out the mistake. The two operations,
: "Annales MSdico-Psychologiques," ibid. I have myself had, in a dream
it is true, a vision of this kind (November, 1869). At the end of a dream, too
long for narration, my own figure appeared seated in an arm-chair near a table,
in a white dressing-gown striped with black ; it turned towards me, and the shock
was so great that I woke up with a start.
CHAP. I.] THE NATURE AND REDUCTION OF IMAGES. 49
illusion and its rectification, follow so closely that they are
confused into one. But suppress the rectification, the first
operation,, illusion, will alone remain, and its unaccustomed
presence, when the couple is dissolved, will show us its
fugitive presence in the couple when intact.
IV. This leads us to the consideration of cases in which
the rectification cannot be effected. What usually effects
it is the presence of a contradictory sensation. When the
chess-player imagines a black and white chess-board two
paces in front of him, and a moment afterwards his open
eyes give him the sensation of a grey or dark wall at the
same distance, and in the same direction, the sensation and
image cannot co-exist. When the novelist imagines the
crushing of moistened arsenic in his mouth, and " the horrible
inky taste" which the poison leaves, if, a moment afterwards,
he takes a mouthful of wine or a lump of sugar, the real
and imaginary sensations exclude one another, and the
momentary illusion caused by the image disappears under
the ascendancy of the sensation. And thus it is that in
most instances the passing error, connected for a moment
with the presence of the image, disappears, if not at the
same instant, without any appreciable interval elapsing, by
the opposing shock of the real sensation. Let us look,
then, for a case in which the sensation disappears and
becomes as it were absent ; we find such a case in the reverie
preceding sleep.* The sensations produced in us by the
external world are then effaced by degrees ; at last they seem
suspended, and the images, no longer distinguished from
sensations, become complete hallucinations. M. Maury
succeeded, by having himself awakened at intervals, in
observing a great number of them : for example, once, when
suddenly roused up, " I saw my name very distinctly on a
sheet of white paper, shining like the very smoothest
English paper." He seated himself again in his easy-chair.
* Maury, "Annales Medico-Psych ologiques, " 3 me Serie, iii. 161. And "Le
Somtneil et les Reves," chap. iv. M. Maury was the first to show, by a well-
connected series of experiments, the near relationship of the sensation, the recol-
lection, the image, aiid the hallucination.
E
50 OF IMAGES. [Boox II.
" My head had scarcely sunk down before the hallucina-
tion returned j but now, instead of my name, I saw Greek
letters and words which I spelt out mechanically, and
almost with a movement of the lips. On several successive
days I had, whether in bed or my chair, similar hallucinations
or real dreams, in which I appeared to be reading Oriental
characters. This reading of a word here and there was
always accompanied by a feeling of fatigue in the eyes.
.... Once, above all, I saw Sanscrit characters ranged in
columns, according to the classification of grammarians, and
these letters had a relief and a brilliancy which tired me.
It must be observed that I had for some days been reading
a number of grammars of Asiatic languages, and that the
fatigue of my eyes was partly owing to this prolonged read-
ing." Here we not only have the image which has become
an hallucination,* but we see it in process of becoming such.
We can watch the progressive diminution of the sensation
which would contradict it, the suppression of the rectifica-
tion which would pronounce it internal, and the increase of
the illusion which causes us to take the phantasm for a
real object. f
I know this state from my own experience, and have
many times repeated the observation, above all in the day-
time, when fatigued and seated in a chair ; it is then suffi-
cient for me to close one eye with a handkerchief; by de-
grees the sight of the other eye becomes vague, and it closes.
By degrees, all external sensations are effaced, or cease, at
all events, to be remarked ; the internal images, on the other
hand, feeble and rapid during the state of complete wake-
fulness, become intense, distinct, coloured, steady, and last-
ing ; there is a sort of ecstasy, accompanied by a feeling of
expansion and of comfort. Warned by frequent experience,
I know that sleep is coming on, and that I must not dis-
* Brierre de Boismont, op. cit. 160. Mdlle. R., after a series of hallucinations,
" characterized very clearly the state sbe had gone through. She could best com-
pare it, she said, to an unpleasant dream." Many sufferers from hallucinations
have said the same, on their recovery. The analogy between dreams and halluci-
nations is certain. See Maury, ibid. chap. vi.
f Mueller, Physiology, tr. Baly, ii. 1394.
CHAP. I.] THE NATURE AND REDUCTION OF IMAGES. 51
turb the rising vision ; I remain passive ; and, in a few
minutes it is complete. Architecture, landscapes, moving
figures, pass slowly by, and sometimes remain, with incom-
parable clearness of form and fulness of being ; sleep comes
on, and I know no more of the real world I am in. Many
times, like M. Maury, I have caused myself to be gently
roused at different moments of this state, and have thus
been able to mark its characters. The intense image which
seems an external object is but a more forcible continuation
of the feeble image which an instant before I recognised as
internal ; some scrap of a forest, some house, some person
which I vaguely imagined on closing my eyes, has in a
minute become present to me with full bodily details, so
as to change into a complete hallucination.* Then, waking
up on a hand touching me, I feel the figure decay, lose
colour, and evaporate ; what had appeared a substance is
reduced to a shadow. I have frequently thus watched in
turn the filling out by which a simple image becomes an
hallucination, and the obliteration which turns the halluci-
nation into a simple image. In this double transition, we
are able to notice the differences, and perceive the conditions
of the two states.
First, when we are going to sleep. As the image
becomes more intense so it becomes more absorbing and
independent. On the one hand, it attracts by degrees all
the attention ; external noises and contacts become less and
less sensible ; at last they are as if they did not exist. The
image, on the other hand, becomes prominent and persis-
tent ; we seem no longer actors, but spectators ; its trans-
formations are spontaneous and automatic.^ When attention
and automatism are at their height, the hallucination is
* Maury, " Le Sommeil," 3 me edition, pp. 448 and 453. Many instances are
cited in support of this. "As soon as the mind rests on an idea, a corresponding
hypriogogic hallucination is produced, if the eye be closed The state
of hallucination is nothing more than an intensity of the image-idea, owing to
the internal parts of the sensorial apparatus having become more delicate and more
readily excitable, and consequently undergoing, in the operation of conception, a
more vigorous shock than in the healthy state a shock, however, of the same
nature as that which accompanies thought."
t An expression of M. Baillarger.
E2
52 OF IMAGES. [Boos II.
complete, and it is precisely by the loss of these two cha-
racters that it is destroyed. Next, as to waking. On the
one hand, at the light touch that arouses us, a part of our
attention is Drought back to the outer world. On the
other hand, as memory returns, reviving images and ideas
surround with their train the special image, they come into
conflict with it, assume ascendancy over it, depose it from
its solitary position, restore it to social life, and replace it in
its habitual dependency. This opposition and contention
cause the stupefaction of waking, and what we call being
thoroughly awake is but the re-establishment of equili-
brium.
The ordinary image then is not a simple, but a double
fact. It is a spontaneous consecutive sensation, which, by
conflicting with another sensation, primitive and not sponta-
neous, undergoes lessening, restriction,, and correction. It
comprises two momentary stages, a first in which it seems
localized and external, and a second in which this exter-
nality and situation are lost. It is the result of a struggle ;
its tendency to appear external is opposed and overcome by
the stronger and contradictory tendency of the sensation
occasioned at the same moment by the action of the nerve.
Under this effort it grows weak and thin, it is reduced to
a shadow ; we call it an image, phantasm, or appearance,
and, however vivid or clear it may be, the conjunction of
this negation is sufficient to deprive it of its substance; to
dislodge it from its apparent position, and to distinguish it
from the true sensation.
But to take the inverse case; it is allowed that not
only in sleep but when awake, and for instance in a state
of ecstasy or in the heat of action, though the nerve be
excited, the sensation may be absent or as if absent, that
is to say, not observed, annulled by the presence and pre-
ponderance of some other idea, image, or sensation. Such
instances are by no means rare. At the bombardment of
St. Jean d'Ulloa, the Mexicans fired a number of shot
into a French vessel. A sailor called out " All right ! No
harm's done/' The next minute he fell, fainting ; a ball
CHAP. I.] THE NATURE AND REDUCTION OF IMAGES. 53
had broken his arm ; at the moment he did not feel it.*
So too in a calmer state, we may find sensations or frag-
ments of sensations which are destroyed and no longer
capable of contradicting the image. The image will then
appear localized and external ; and, though pronounced
illusory by surrounding ideas, will continue to appear
localized and external, since the sensation which could alone
deprive it of this character is wanting, or is as if it did not
exist. The hallucination is then complete, and what makes
it so is the annulling the only sensation or fragment of sen-
sation capable of reducing it. When a man under an hal-
lucination, with his eyes open, sees three feet from him
the figure of a man where there is really a mere wall
covered with a grey paper with green stripes, the figure
covers a portion of this wall and renders it invisible to him ;
the sensations which this portion ought to excite are then
non-existent ; but nevertheless the retina, and probably the
optic centres, are excited in the ordinary manner by the grey
and green stripes. In other words, the preponderating image
annuls the portion of sensation which would contradict it. If,
as it often happens, the figure moves, -the preponderating
image, as it advances and covers each portion of the wall, is
continually blotting out and exposing in turn distinct frag-
ments of sensation. Reason is not wanting in such cases ;
for often when in this state the mind remains sound and the
patient knows that the figure is not real ; it is the special
reductive, that is to say, the contradictory sensation, which
fails in the conflict, and, instead of depriving the image of
its externality, becomes itself effaced.
Accidents of this kind are frequent when one of the
senses has been greatly fatigued. " It is well known that
persons who are in the habit of using the microscope some-
times find objects which they have been examining for a long
time re-appear spontaneously some hours after they have
left their work."f M. Baillarger having worked some hours
* This fact was told me by an eye-witness.
t Baillarger, " Des Hallucinations," 460.
54 OF IMAGES. [BOOK II.
daily for several days, at preparing specimens of brains with
fine gauze, " saw all at once gauze continually covering the
objects in front of him And this hallucination was
repeated for several days." Here, it is evident the special
reductive was wanting ; in other words, the retina having
before it a green carpet, or red chair, certain lines of green
or of red, while producing on it their ordinary physical
effect, excited only a sensation amounting to nothing. For
this reason, a German physiologist, Gruithuisen,* who has
observed his own hallucinations with great accuracy, affirms
that he saw floating images cover the furniture of the room
he was in.
Other cases show the partial re-establishment of the
corrective sensation. A person, mentioned by Sir Walter
Scott,t saw a skeleton at the foot of his bed. His doctor,
wishing to convince him of his error, placed himself be-
tween the patient and the place assigned to the spectre.
The patient then professed that he could not see the body
of the skeleton, but that its skull was peering' over the
doctor's shoulder. This is why solitude, silence, obscu-
rity, the want of attention, all circumstances, in short,
which suppress or diminish the corrective sensation, facili-
tate or provoke the hallucination; and reciprocally, com-
pany, light, conversation, aroused attention, all circum-
stances giving rise to, or augmenting, the corrective sensa-
tion, destroy or weaken the hallucination .\ " If we ap-
proach a patient suffering under hallucinations of hearing, and
speak to him so as to fix his attention, we can convince him
that his pretended invisible interlocutors are silent while
the conversation lasts "A patient observed by M.
Lelut, at the hospital of the Bicetre, " ceased to have hallu-
cinations when changed into another ward and with different
neighbours. But this suspension lasted only a few days ;
* Baillarger, ibid. 333-334. f "Demonology and Witchcraft," p. 27.
Baillarger, ibid. 440 ; and Brierre de Boismont, op. cit., 388. " Those
nightly apparitions, which I called silly illusions by day, became frightful realities
to me in the evening." p. 388." It constantly happened that the entrance of the
servant freed her from the presence of the phantoms." p. 242.
CHAP. I.] THE NATURE AND REDUCTION OF IMAGES. 55
the patient soon became accustomed to the new circum-
stances in which he found himself, and then fell again into
false perceptions , With one patient there must be
verv keen impressions, uninterruptedly kept up, to suspend
the hallucinations even for a short time. Scarcely is the
sick man left to himself, scarcely have you ceased to excite
him, when the phenomena recur. With other s, on the
contrary, the visit of the doctor to the ward is enough to
cause a considerable suspension." When M. Baillarger
saw objects covered with gauze " it was principally in the
dark, and when my attention was not engaged/'* The
same observer, having taken haschich, could not get rid of
his hallucinations while in the dark, and was compelled to
light a candle. Many patients who see in the dark various
frightful figures, dying persons, corpses, &c., are freed from
their visions as soon as a light is brought into the room.
A lady with whom this is the case has been obliged for
twenty years to have a light near her when asleep. An
old servant, M. G., " as soon as she closes her eyes, sees
animals, houses, meadows, &c. I have frequently myself
pressed down her eyelids, and she described at once a crowd
of objects which appeared to her/' With some people,
to enter a dark room is enough to produce hallucinations.
" It is not then uncommon/' says Mueller ,t " to find dis-
tinct images of landscapes and similar objects floating before
the eyes. I have been very subject to this phenomenon,
but have got into the habit, whenever it occurs, of opening
my eyes at once, and fixing them on the wall. The images still
persist, but soon grow pale. They are seen whichever way
the head is turned." Here the remedy is obvious ; it con-
sists in arousing a contradictory sensation. The phantom
grows pale, and loses its externality in proportion as the sen-
sation of colour excited by the wall becomes more clear and
preponderant. And the remedy is general ; every shock that
brings back the attention to real sensations ; a cold bath, a
* Ibid. 328, 329-330, 445-444.
f Op. cit., tr. Baly, ii. 1394.
56 OF IMAGES. [BOOK II.
douche, the arrival of an unexpected or important person,
draws them from their indistinctness and nullity, re-esta-
blishes them more or less, and for a longer or shorter time,
and consequently revives with them the particular sensation
which is the special reductive of that illusion.
"In the summer of 1832,* a gentleman in Glasgow, of
dissipated habits, was seized with cholera, from which he
recovered. His recovery was unattended with anything
particular, except the presence of phantasmata consisting of
human figures about three feet high, neatly dressed in pea-
green jackets, and knee-breeches of the same colour. Being
a person of a superior mind, and knowing the cause of
the illusions, they gave him no alarm, although he was
very often haunted by them. As he advanced in strength
the phantoms appeared less frequently, and diminished
in size, till at last they were not taller than his finger.
One night, while seated alone, a multitude of these
Lilliputian gentlemen made their appearance on his table,
and favoured him with a dance; but being at the time
otherwise engaged, and in no mood to enjoy such an amuse-
ment, he lost temper at the unwelcome intrusion of his
pigmy visitors, and striking his fist violently on the table, he
exclaimed, in a violent passion, ' Get about your business,
you little impertinent rascals ! What the devil are you
doing here ?' when the whole assembly instantly vanished,
and he was never troubled with them more." The
illness was drawing to a close, and his lively feeling of
anger, together with the violent sensation of the blow on
the table, suddenly restored their normal preponderance to
the visual sensations which the portions of the table covered
by the Lilliputians ought to have given him, but had ceased
to give.
Other cases show with fuller detail how it is the correc-
tive sensation leaves the sides, and appears On the scene.
Mcolai,f the bookseller and academician of Berlin, having
* Macnish, " Philosophy of Sleep," p. 290.
t Brierre de Boismont, op. cit. 33, citing from Berliner Monats-schrift. 1799.
CHAP. I.] THE NATURE AND REDUCTION OF IMAGES. 57
suffered from considerable vexations, and a periodical blood-
letting to which he was accustomed having been omitted,
tells his story thus: (C On the 24th of February, 1791,
having had a violent altercation, I saw on a sudden, about
ten paces from me, the figure of a corpse The appa-
rition lasted eight minutes. At four in the afternoon, the
same figure re-appeared At six, I distinguished
several figures having no connexion with the first. . . . On
the following day, the figure of the corpse disappeared ; it
was replaced by other figures, sometimes representing friends,
but more frequently strangers These visions were
as clear and distinct in solitude as in company, by day
as by night, in the streets as in my own house ; only they
were less frequent when in strange houses." They repre-
sented men and women walking as if on business, then per-
sons on horseback, dogs, and birds. There was nothing par-
ticular in their looks, stature, or dress, " but they were a little
paler than in real life"* At the end of four weeks, their
number increased ; they began to talk to one another, and
sometimes to address him, usually in pleasing language.
He distinguished clearly these involuntary hallucinations
from voluntary images. When certain figures he was ac-
quainted with had thus passed before him, he determined
to attempt to reproduce them mentally. " But," says he,
" while seeing distinctly in my mind two or three of them,
I could not succeed in making the internal image external.
.... On the other hand, some time after, I perceived them
afresh when I was not thinking of them." The special re-
ductive was wanting in the hallucination ; on the other hand,
it was at work in the case of ordinary attention, and simply
because the degree of attention was ordinary. In the first
* M. Brierrede Boismont (op. cit. 240) gives an account of a person who, during
an attack of pneumonia, had hallucinations of this kind, while preserving, like
Nicolai, all his reason.
" Sometimes these figures presented themselves suddenly, but more frequently
did not become distinguishable till after an interval, as though they had passed
through a mist before showing themselves distinctly. Each figure remained
visible five or six seconds, then disappeared, getting feebler by degrees till nothing
remained but an opaque dull cloud, from the midst of which another figure imme-
diately appeared."
58 OF IMAGES. [BOOK II.
case, the image arising of its own accord, spontaneously,
without visible connexions or antecedents, and with per-
sonal automatic power, destroyed the special reductive. In
the second case, the image arising by an effort of the
balanced group of ideas and desires which we term our-
selves, allowed the special reductive to do its work. After
about two months, leeches were applied to the patient to
make up for the omitted bleeding, and he found his normal
sensations reappear, not all at once, but by portions and
degrees. " During the operation," says he, " my room was
filled with human figures of all kinds. This hallucination
lasted uninterruptedly from eleven in the morning to half-
past four, just when my digestion was commencing. I then
perceived the movements of the phantoms getting slower.
Soon afterwards they began to grow pale : at seven they
had a whitish look, they moved very slowly, though their
outlines were as distinct as before. By degrees they be-
came misty, and appeared to dissolve into air, whilst certain
portions of them remained still visible during a considerable
time. At about eight o'clock, the room was quite clear of
these fantastic visitors."
When we are suddenly roused from sleep in the midst of
a vivid dream, we experience an impression like this, though
of far shorter duration. In such a case, I have often seen,
for a passing moment, the image grow pale, waste away, and
evaporate ; sometimes, on opening the eyes, a fragment of
landscape or the skirt of a dress appears still to float over
the fire-irons or on the black hearth. So, while Nicolai was
recovering, the parts of the wall or furniture covered by the
phantoms succeeded by degrees in producing their normal
effect. The sensation which they would naturally excite by
their action on the nerve, and through that on the brain,
is no longer paralysed. At first, this sensation recovers a
portion of its strength, and contends on equal terms with
the image ; for the phantom, if still present, is misty, and
the furniture or wall is vaguely apparent behind it. Soon,
a fragment of the sensation regains all its preponderance ;
a leg or the head of a phantom disappears owing to the re-
appearance of the portion of furniture which it hid. Then,
CHAP. I.] THE NATURE AND REDUCTION OF IMAGES. 59
the whole sensation finds itself restored and complete, the
phantoms have vanished, and all that remains of them is
the internal image which enables us to describe them.
Here we see very clearly the connexion of the image and
sensation ; it is an antagonism, such as is met with between,
two groups of muscles in the human frame. In order that
the image may produce its normal effect, that is to say, may
be recognised as internal, it must undergo the counterpoise
of a sensation ; and if this counterpoise is absent, it will
appear external. Similarly, in order that the muscles on
the left of the face or tongue may produce their normal
effect, the corresponding muscles on the right must be in-
tact. In the absence of this counterpoise, the face or
tongue are drawn towards the left. The paralysis of the
muscles of one side produces a deformation of the other, as
the weakening or extinction of the reductives of an image
produces an hallucination.
As a general rule ; normal sensations of any one sense,
and usually those of the different senses, hold together. We
have seen many proofs of this in the cases cited. When the
attention is attracted by a normal sensation, that is to say,
when this sensation regains its ordinary preponderance, the
chances are that the other annulled sensations regain their
ascendancy at the same time. The patient who is freed at
once from his illusions by the light of a candle, the unfor-
tunate man who hears voices which cease when conversa-
tion becomes interesting, the lunatic who regains his senses
after a sudden dash of cold water, are cured for a longer or
shorter time by the more or less durable energy restored to
the special reductive. So, in facial paralysis, the face drawn
on one side by the action of the left muscle, regains its
ordinary form as the muscles on the right gradually regain
their power under the action of electricity.
In other cases the cure follows from the same principles,
but is obtained by an inverse process ; I mean those in
which the patient is haunted, not by hallucinations, that is
to say, by images capable of annulling the normal sensation
which ought to counteract them, but by illusions, that is to
sav ; by images excited by the normal sensation, and so
60 OF IMAGES. [BOOK II.
strong, precise, and absorbing that no actual sensation from
without could have greater power. A state of excitement
and expectation in the subject will often cause a sensa-
tion, which would be accompanied in a calm state by
images of moderate activity, to communicate an extraor-
dinary clearness and force to the image. " A whole ship's
crew were thrown into consternation by the ghost of
the cook, who had died a few days before. He was dis-
tinctly seen by them all, walking on the water with a pecu-
liar gait by which he was distinguished, one of his legs
being shorter than the other. The cook, so plainly recog-
nised, was only a piece of old wreck."* The superstitious
sailors who had the figure of their shipmate and his gait
fresh in their minds, all, without previous concert, under-
went the same illusion at the sight of the uneven motion of
the wreck, and their imagination found in the sensation a
ground to build on.
What was here effected by credulity may be caused by
disease. We see insane persons who lick the surface of a
wall and imagine themselves to taste delicious oranges, or
who, when given ripe fruit, find it rotten or poisoned ; who,
when they see one person, insist on taking him for another ;
who see the furniture of their room move about, grow
bigger, or take fantastic and frightful forms, f In such
cases it often happens that by suppressing the normal sen-
sation, which is the starting point of the illusion, we sup-
press the illusion itself, and the special reductive is found, not
in the predominance, but in the absence of that sensation. J
" D. , seventy-five years old, of sound mind, came
home one day, frightened by a thousand phantoms which
were following him. Whichever way he looked, objects
were transformed into spectres, representing sometimes
huge spiders which ran at him to drink his blood; some-
* Moore, " The Power of the Soul over the Body," p. 170.
+ Brierre de Boismont, op. cit. 777. This was the case with Don Quixote ; the
sensation of two great whirlwinds of dust excited in him the image, and conse-
quently the sensation, of two arruies.
$ See Griesinger, op. cit. 103, for different instances.
CHAP. L] THE NATURE AND REDUCTION OF IMAGES. 61
times soldiers with pikes. He was bled in the foot; the
visions continued, accompanied by obstinate attacks of
sleeplessness ; a bandage was applied to his eyes ; then they
ceased, but returned as soon as the bandage was taken off,
until the patient kept it on uninterruptedly for a night and
part of a day. From that time he only saw phantoms at
long intervals, and after some days they disappeared en-
tirely. The patient has had no relapse." Here, in place of
strengthening the special reductive, the special excitant was
suppressed, and the same result arrived at by different
means.
In a very curious observation made by Dr. Lazarus on
himself, we see no less clearly how the exciting sensation,
alternately present and absent, alternately excites and sup-
presses the illusion. " I was on the Kaltbad terrace at
Rigi, on a very clear afternoon, and attempting to make out
the Waldbruder, a rock which stands out from the midst of
the gigantic wall of mountains surrounding it, on whose
summits we see like a crown the glaciers of Titlis, Uri-
Kothstock, &c. I was looking alternately with the naked
eye and with a spy -glass ; but could not distinguish it with
the naked eye. For the space of six to ten minutes I had
gazed steadfastly upon the mountains, whose colour
varied according to their several altitudes or declivities
between violet, brown, and dark green, and I had fatigued
myself to no purpose, when I ceased looking and turned
away. At that moment I saw before me (I cannot recol-
lect whether my eyes were shut or open) the figure of an
absent friend, like a corpse. I ought here to mention that
I have been for years in the habit of noting down in writing
every group of representations which has arisen, whether
dreaming or awake, with special force, precision, and clear-
ness, and has affected me vividly enough to induce the
thought of the representation as a presentiment. I ought
further to mention that I have never had the fortune to see
one of such presentiments verified, though they have often
been as sudden, clear, and apparently inexplicable, as one
could wish. In addition to this, I have acquired the habit,
62 OF IMAGES. [Boos II.
intelligible enough in a psychologist, of tracing backwards
from such incidents, and following up the whole series of
antecedent representations. I have very often succeeded
in explaining, by the known laws of association of ideas,
how such presentiments have contrived to find place in the
series of my thoughts at the time.
" On this present occasion, I asked myself at once how
I had come to think of my absent friend ? In a few seconds
I regained the thread of my thoughts, which my looking for
the Waldbruder had interrupted, and readily found that
the idea of my friend had by a very simple necessity intro-
duced itself among them. My recollecting him was thus
naturally accounted for. But in addition to this, he had
appeared as a corpse. How was this? At this moment,
whether through fatigue or in order to think, I closed my
eyes, and found at once the whole field of sight, over a con-
siderable extent, covered with the same corpse-like hue, a
greenish-yellow grey. I thought at once that I had here
the principle of the desired explanation, and attempted to
recall to memory the forms of other persons. And, in fact,
these forms too appeared like corpses ; standing or sitting,
as I wished, all had a corpse-like tint. The persons whom I
wished to see did not all appear to me as sensible phantoms ;
and again, when my eyes were open, I did not see phantoms,
or at all events only saw them faintly, of no determined colour.
I then inquired how it was that phantoms of persons were
affected by and coloured like the visual field surrounding
them, how their outlines were traced, and if their faces and
clothes were of the same colour. Eut it was then too late,
or perhaps the influence of reflection and examination had
been too powerful. All grew suddenly pale, and the sub-
jective phenomenon, which might have lasted some minutes
longer, had disappeared. It is plain that here an inward
reminiscence, arising in accordance with the laws of asso-
ciation, had combined with a consecutive sensation of sight.
The excessive excitation of the periphery of the optic
nerve, I mean the long-continued preceding sensation of my
eyes when contemplating the colour of the mountain, had
CHAP. L] THE NATURE AND REDUCTION OF IMAGES.
r indirectly provoked a subjective and durable sensation, that
of the complementary colour ; and my reminiscence incor-
porating itself with this subjective sensation, became the
corpse- like phantom I have described."* This singular case
shows us the abnormal effect of sensation. When it exists,
it increases the force and clearness of an ordinary vague
representation till it turns it into a sensible phantom. When
it ceases, the force and clearness of the sensible phantom are
decreased, till it returns to its ordinary state, that is, one of
vague representation.
Thus, in every process by which the exaggeration of
images is combated, all we attempt is to set up an equili-
brium, not that of a balance of which the two scales are on
a level, but that of a balance in which one scale is lower
than the other. In the normal state of wakefulness, the
first scale which holds the sensations proper, is the heavier;
the second and lighter scale holds images proper. The two
scales in the normal state are, for the moment, on a level ;
but the heavier scale immediately weighs down the other,
and our images are recognised as internal. Sometimes, in
illness, a weight passes from the first to the second ;
the second then weighs down the first, and we have an
hallucination proper; we are then obliged to add new
weights, that is, new sensations, to the first, to destroy the
preponderance. Sometimes, again, a thread attaches a
weight of the second scale to a weight of the first, the first
scale can no longer descend, and we have an illusion proper ;
the first means are no longer applicable ; it would be idle to
add new weights, we must remove from the first scale the
weight with the thread which keeps the scales on a level,
in spite of the inequality of their loads. In the first case,
the normal state is re-established by adding ; in the second,
by taking off, weights.
V. But these are not the only means in question ; for,
in addition to the weights constituted by the sensations,
there are others, lighter, but still usually sufficient in the
* " Zur Lehre von den Sinnestauschungen," Berlin, 1867.
IMAGES. [BOOK II.
healthy state to deprive the image of its externality ; I
mean recollections. These recollections are themselves
images, but connected together and undergoing a recoil
which gives them a situation in time, by a mechanism
we shall inquire into hereafter. General judgments ac-
quired by experience are associated with them, and form
with them a group of elements connected among them-
selves, and so balanced, by their relations to one another,
as to form a whole of considerable cohesion, and lending
its entire force to each of its elements. Every one may
observe in his own case the reductive power of this
group. A few days ago, I had a very clear and perfectly
connected dream, in which I committed a ridiculous and
enormous absurdity, too much so to describe ; let us take
something less glaring, such as quietly drawing off one's boots
in company, and placing them on the mantelpiece beside
the clock. It happened in a drawing-room I like very much ;
I saw distinctly the principal guests, their dress, their atti-
tudes, I spoke to them, the scene was long, and the impres-
sion so clear that a quarter of an hour after I could have
described it with every detail. I felt ill at ease, and was
wondering howl could get out of my difficulty. Just then I
began to awake, and this state lasted two or three minutes,
My eyes were still closed ; but probably, through some feel-
ing of cold or actual movement, ordinary consciousness was
reviving, though feebly. In the first place, I was astonished
at having shown such frightful ill- breeding ; in other words,
the vague recollection of my previous actions rose up, and
came into opposition with my dream ; this recollection be-
came more precise, and brought on others ; the lines of the
past were reformed, and at the same time and in the same
degree, the absurdity I had dreamed of, finding no standing-
room, disappeared and evaporated. Then came this judg-
ment, based on general ideas : " It is a dream." The
ridiculous image, at once and definitively, became distinct
and severed, from the real recollections, and entered the
region of pure phantasm. I had not yet opened my eyes ;
the sensation of present objects had not performed its work;
CHAP. I.] THE NATURE AND REDUCTION OF IMAGES. 63
at all events, it had only done so to the extent of reviving
ordinary recollections and general judgments ; these judg-
ments and recollections, by the fixedness of their order and
the cohesion of their group, had effected the necessary
reduction, and overcome the natural tendency by which the
image causes illusion.
In some cases this repression is much slower. M.
Baillarger dreamed one night that a certain person had
been appointed editor of a newspaper ; in the morning, he
believed it to be true, and mentioned it to several persons,
who were interested to hear it; the effect of the dream
persisted all the forenoon, as strongly as that of a real sen-
sation ; at last, about three o'clock, as he was stepping into
his carriage, the illusion passed off; he comprehended
that he had been dreaming; so here the reductive group
did not regain its ascendancy for half a day. In this
respect, the detail and intensity of a voluntary image
have sometimes the same power as a dream. We find
many examples of this in the lives of Balzac, Gerard de
Nerval, Edgar Poe, and other great artists. Balzac once,
at the house of Mme. Delphine Gay, was describing with
animation a fine white horse he intended to present to
Sandeau ; some days after he imagined he had actually
given it, and inquired of Sandeau about it ; probably, his
friend's astonishment and denial disabused him of the notion
of his present.
On other occasions, the reductive group is weakened, and
is not sufficient to check even an ordinary image. " An
old man," says M. Maury, " who had travelled a great deal,
had also read many accounts of travels over ground where
he had not been. The recollections of his wanderings and
of his readings had ended by becoming completely confused
together ; and all seemed to occur at once to his mind as
he lay on his sofa, and he would gravely relate things
he had read. For example, he would say that he had been
in India with Tavernier, in the Sandwich Isles with Cook,
and had then returned to Philadelphia, and had served
there under Lafayette. This last statement was true."
66 OF IMAGES. [Boos II.
The notions of chronology and order of time were effaced,
and no longer performed their ordinary office.
Persons with lively imaginations are constantly forced
to make reductions which this old man had ceased to make ;
the general order of their recollections,, fortified by the
addition of some new observation, is generally sufficient for
this. But when an image has acquired extraordinary inten-
sity, and annuls the particular sensation which is its
special reductive, though the order of recollections may exist
and conclusions be come to, we have, nevertheless, an
hallucination; in fact, we may know that we are under an
hallucination, but still the image appears external; our
other sensations and images still form a balanced group, but
this reductive not being the special one, is insufficient.
" Dr. Gregory had gone to the north country by sea, to
visit a lady, a near relation, in whom he felt deeply inte-
rested, and who was in an advanced state of consumption.
In returning from the visit, he had taken a moderate dose
of laudanum, with the view of preventing sea- sickness, and
was lying on a couch in the cabin, when the figure of the
lady appeared before him in so distinct a manner that her
actual presence could not have been more vivid. He was
quite awake, and fully sensible that it was a phantasm
produced by the opiate, along with his intense mental feel-
ing, but he was unable by any effort to banish the vision."*
In fact, the sensation which ought to have been produced
in him by the grey wall of the cabin was annulled as re-
garded the whole surface which the phantom seemed to
cover ; and it is very clear that reasoning has not the force
of a sensation. Many circumstances, organic or moral, the
action of haschich,f of datura, of opium, the coming on of
apoplexy, different inflammatory diseases, different cerebral
alterations, in short, a number of causes, more or less remote
or near, are capable of thus strengthening an image or
* Abercrombie, "Inquiry concerning the Intellectual Powers," p. 359.
f Brierre de Boismont, ibid. 200. Accounts giveu by several persons who had
taken haschich. Ibid. 374.
CHAP. I.] THE NATURE AND REDUCTION OF IMAGES. 67
series of images so as to annul the special sensation which
should repress it, and thus bring on hallucination. But if
in all these cases the illusion, circumscribed by secondary
reductives, is at last destroyed by the special one, we meet
with a still greater number in which this is not the case.
Very frequently, patients, having admitted for a length of
time that their phantoms were only phantoms, have ended
by believing them to be real, and equally real with the persons
and objects surrounding them, and this too with so absolute a
conviction that no experience of their own or evidence of
others can cure them of their error. In such cases the
second class of reductives are annulled, as well as the special
one ; the preponderating image, having paralysed the con-
tradictory sensation, extends its dominion over the contra-
dictory group of other normal images, and excites delirious
ideas and unreasonable impulses. The person under hallu-
cination becomes a madman ; the loss of local equilibrium
has gradually brought on an increasing loss of general
equilibrium, as the paralysis of the muscles on the right,
after causing a deformation and shrinking of the face
towards the left, may affect by sympathy the adjoining
functions, and produce general disease throughout the body.
Examples of this are numerous ; I have chosen one, re-
ported by Dr. Lhomme, which shows in detail the several
stages of this spontaneous transformation, and throws great
light on the mechanism of the mind.
In March, 1862, the gendarme S. was on duty at an exe-
cution. He was on guard with the prisoner during part of
the night, assisted at the toilette, and was a few feet from
the scaffold when the execution took place. When the head
fell, he saw the executioner take it up to put it in the basket.
.... He says that this made a deep impression on him ; he
had been seized with a nervous trembling which he could
not control, at the moment he saw the prisoner brought up
with his outer clothes removed and neck bare ; and long
after the execution, the figure of the bleeding head which he
had seen thrown into the basket was constantly before him.
Some time after, talking with the quartermaster, he said
F2
68 OF IMA GES. [BOOK II.
that he had no great opinion of Protestants. "He told me
I was wrong; that there were many very good people
among them, and even some persons of high rank, and
mentioned, as -an instance, the Minister of War. I kept
thinking of this conversation, and it came into my head that
the quartermaster would probably report me to the Minister
of War. Some days afterwards I dreamed that I was actu-
ally condemned to death by the Minister's order, without
having had a trial. I thought in my dream that / was
bound with straps and was being rolled like a barrel towards
the guillotine. This dream impressed me vividly. I told it
to a comrade, who laughed at me, but it often recurred to
my mind!"
On the 1st of August, going from Sancerre to San-
cergues, he got drunk, arrived too late, and found the bar-
racks closed. Next day the quartermaster told him that
he should report him to the lieutenant for being late.
The 2nd of August he was " out of spirits, but not ill."
The 3rd of August, he says, " I did not feel all right,
though I had slept well ; / kept thinking of my dream
When I went on duty as sentry, I thought every one was
staring at me, and that I heard my comrades and other
persons whispering that I was going to be guillotined."
That evening he went to bed at eleven, having cleaned his
accoutrements for next day's drill. " I had perhaps been
in bed twenty minutes, and had not fallen asleep, when I
heard a noise in the clock over the mantelpiece, and then
a voice came from it, and said to me, " You must die, you
must die. Your head will be cut off in two days. We must
have your head, we must have your head !" He started up
and looked in the clock, but there was nothing to be seen,
so thinking it a joke of his comrades, he went to bed again.
The voice began again, and he was looking about during
part of the night. About four in the morning he rose,
without having slept, and went to drill, but said nothing of
the voice he had heard, as he " still thought that his com-
rades had been playing him a trick." Coming back he was
tired, but could not eat, and cleaned his accoutrements ; he
CHAP. I.] THE NATURE AND REDUCTION OF IMAGES. 69
felt no inclination to sleep, and did not go to bed till one
in the morning. He was scarcely in bed when he heard
the same voice and same words proceeding from the clock.
" Then I rose and walked up and down, very certain that
they would execute me next morning, and that that was
why the lieutenant had remained at Sancergues."
He rose early. " The quartermaster was surprised to
see me ready so soon, and said something in a low tone
to my comrades. 7 thought I heard, ' See that your car-
bines are loaded ; watch him that he does not escape \ 9 '
On this he found his horse, and set off at a gallop without
knowing where he was going. At last he came to a wood, got
off, and hid himself in a thicket, and loaded his carbine to
defend himself ; then he determined to kill himself, and took
off his boots that he might draw the trigger with his foot,
but first knelt to say a prayer. " I was soon interrupted by
a figure with a huge beard, who disappeared as soon as I took
aim at him ; and three times running I was stopped by
the same apparition or by figures of Punch, which dis-
appeared as 1 was going to fire. I saw also girls with
hooped petticoats, dancing in the trees above my head."
The other gendarmes came up ; he threatened to fire
on them, attempted to take off his white breeches to hide
himself better ; then, hearing them return, he fired on the
foremost of them, and attempted to escape, but was taken.
" I was quite convinced that they were going to take me to
execution, and called out ' Murder V I even thought more
than once that I saw a gendarme draw his knife from his
pocket to stab me, and my cries increased." He was bound,
and a guard put over him, and did not sleep all night.
ff I continually heard female voices saying, ' Poor fellow !
how unfortunate ! He must be guillotined in two hours, and
his head sent to Paris by six o'clock. The quartermaster has
the basket for it. 3 The whole day and night of the 6th I
had the same ideas, and could not sleep for a moment or
take any kind of nourishment. It was not till the 7th that
I was able, during the daytime, to throw myself on my bed
and sleep for a short time. When I woke I found my
70 OF IMAGES. [BOOK II.
head completely clear, though I recollected perfectly all
that had taken place. I expressed my sorrow to my com-
rades for what had passed, and asked at once after the
one I had wounded." From that time the hallucinations
ceased ; the patient's reason is unaffected ; he was calm
and quiet during his stay in an asylum, and is replaced in
the brigade of Gendarmerie, and has regularly performed
his duty since.
Few examples are more instructive than this ; we follow
the hallucination from its first rise to its completed state and
its cure. The mental abscess begins with a terrible image, com-
bined with extreme emotion. The image constantly reviving
besets the mind. It attaches itself to the idea of self, and
S imagines a case in which he may well be in personal
danger. This connexion becomes defined, and in a dream he
sees himself led to the guillotine. The dream returns to his
mind during the day. After he has committed a fault it re-
curs with greater force. The mental words by which he ex-
presses it to himself become a whispering of his comrades, and
then a voice in the clock. The voice returns, and his con-
viction grows firmer. Unconnected hallucinations of sight,
then of the touch, follow. For thirty hours the voices con-
tinue, and the hallucination of the ear is at its height.
Then he becomes suddenly freed from them, as if the
mental abscess having" ripened, had broken of itself.*
VI. From these examples we can form a notion of
our intellectual machinery. We must lay aside the words
reason, intelligence, will, personal power, and even self, as
we lay aside the words vital force, medicative virtue, vege-
tative soul ; they are literary metaphors, capable at the
most of convenient use by way of summary or abbrevia-
tion, to express general states and combined effects. All
that observation detects physiologically in the living being
are cells of different kinds, capable of spontaneous develop-
ment, and modified in the direction of this development by
the concurrence or antagonism of their neighbours. All
* " Annales Medico-PsychoJogiques," 4 e Serie, ii. 238.
CHAP. L] THE NATURE AND REDUCTION OF IMAGES. 71
that observation detects psychologically in the thinking
being are, in addition to sensations, images of different
kinds, primitive or consecutive, endued with certain ten-
dencies, and modified in their development by the concur-
rence or antagonism of other simultaneous or contiguous
images. Just as the living body is a polypus of mutually
dependent cells, so the active mind is a polypus of mutually
dependent sensations and images, and in the one case as in the
other, unity is nothing more than a harmony and an effect.
Every image is possessed of an automatic force, and tends
spontaneously to a particular state ; to hallucination, false
recollection, and the other illusions of madness. But it is
arrested in its progress by the contradiction of a sensation,
of another image, or group of images. The mutual arrest,
the reciprocal clash, the repression, produce by their com-
bined effect an equilibrium ; and the effect we have just
seen produced by the special corrective sensation, by the
connexion of our recollections, by the order of our general
judgments, is but an instance of the constant re-arrange-
ment and incessant limitation which innumerable ID com-
patibilities and conflicts are incessantly bringing about
among our images and ideas. This equilibrium is the state
of reasonable wakefulness. As soon as it is at an end by
the hypertrophy or atrophy of an element, we are mad,
wholly or partially. When it lasts over a certain time,
the fatigue is too great, and we sleep ; our images are no
longer reduced and guided by antagonistic sensations
coming from the outer world, by the repressive effect
of combined recollections, by the dominion of well-con-
nected judgments ; so they then acquire their full develop-
ment, turn into hallucinations, arrange themselves spon-
taneously according to new tendencies, and sleep, though
crowded with intense dreams, is a rest, since, suppressing a
constraint, it brings on a state of relaxation.
But in the meanwhile the reader has been able to ascer-
tain the nature of the image. For this we must remain at
the point at which we have provisionally placed ourselves.
We do not yet enter upon physiology, but confine ourselves
72 OF IMAGES. [BOOK II.
to pure psychology. We do not talk of nerves, spinal
marrow, or brain. We leave aside the unknown excita-
tion which the external extremity of the nerve undergoes
by contact with an external object, and which transmits
itself to the spinal marrow, passes thence to the surface
of the brain, spreads among its circumvolutions, becomes
persistent in the nervous centres, and is, later on, renewed
there. We do not examine the link connecting the sen-
sation with the image. We observe man, not with the
scalpel and microscope, but with that internal view we
call consciousness, and we compare directly the image and
the sensation. In this limited field, and in this precise
sense, we have just seen that the image, with different
physical stimulants, and a special reductive, is of the same
nature as the sensation. It is the sensation itself, but
consecutive or reviving; and from whatever point we con-
sider it, we find it coincide with the sensation. It fur-
nishes the same combinations of derived and superior ideas ;
the chess-player who plays blindfolded, the painter who
copies an absent model, the musician who hears a score
when he looks over the sheet of music, form the same
judgments, go through the same reasonings, and experience
the same emotions, as if the chess-board, the model, the sym-
phony, were actually experienced by their senses. It pro-
vokes the same instinctive movements and the same asso-
ciated sensations : the man who has a disgusting medicine
put before him, who is about to undergo a surgical operation,
who recalls a melancholy or terrible accident, shudders,
sweats, or is sick, in presence of the image alone, as he
would if the sensation were itself present. Though gene-
rally fragmentary, fugitive, and weak, it arrives in many
cases, in the extreme concentration of excessive attention,
in violent and sudden emotions, at a state bordering closely
on the corresponding sensation, and attains the fulness of
detail, the clearness, energy, and persistence of the sensa-
tion. Finally, taken alone and freed from the reduction of
its special corrective, it acquires apparent externality, the
want of which, even at its maximum of intensity, usually
CHAP. I.] THE NATURE AND REDUCTION OF IMAGES.
73
distinguishes it from the sensation ; it acquires this for an
imperceptible moment in the majority of cases ; for some
seconds or minutes in certain well-authenticated instances ;
for several hours, days, or weeks in the states of half sleep,
complete sleep, ecstasy, hypnotism, somnambulism, halluci-
nation ; in the disorders produced by opium or haschich, in
various cerebral or mental maladies ; and acquires it with
or without lesion, or with either partial or total lesion, of
the normal equilibrium which subsists between other ideas
and images. We may define, it, then, as a repetition or
revival of the sensation, while at the same time we distin-
guish it from the sensation ; first, by its origin, since it has
the sensation as its antecedent, while the sensation is pre-
ceded by an excitation of the nerve ; and again, by its
association with an antagonist, since it has several reductives,
among others, the special corrective sensation, while the
sensation itself has no reductive.
Arrived at this we understand its nature : in reviving
the sensation, it replaces it ; it is its substitute ; that
is to say, a thing differing from it in certain respects,
like it in others, but so that both differences and re-
semblances have their advantages. What these advan-
tages are we shall see later on. Images of a certain
kind constitute recollections ; that is to say, knowledge of
past events. Images associated with the sensations of
the different senses, especially with those of sight and
touch, constitute acquired perceptions ; that is to say, all
such parts of our knowledge of external individual objects
as extend beyond actual crude sensation. Images of a
certain kind, and associated in a certain way, constitute
previsions ; that is to say, knowledge of future events.
Just as the knowledge of general qualities is only possible
by the substitution of signs for perceptions and images, so
knowledge, whether of events past or to come, or of the
grouped properties which make up every individual external
object, is only possible by the substitution of images for
sensations. Nature employs, in the two cases, the same
process to arrive at the same effect ; psychology here repeats
74 OF IMAGES. [BOOK II.
physiology. As we see in the history of respiration or of
locomotion a physiological element become, by a slight
modification, the instrument of a more complicated func-
tion, then, by a second additional modification, execute a
still superior function ; so in the history of intelligence, we
see a psychological element give rise, by a small modifica-
tion, to very extended operations, then, by a second added
modification, accomplish operations so complex, so delicate,
and so numerous, that they seem destined to remain for
ever beyond our grasp.
CHAP. II. ] REVIVAL AND OBLITERATION OF IMAGES. 75
CHAPTER II.
LAWS OF THE REVIVAL AND OBLITERATION OF IMAGES.
I. WHEN we see or touch an object,, when we hear a
sound, when we experience a sensation of taste, of smell, of
cold, of pain, in short, any sensation whatever, we usually
retain the image during a second or two, unless some
other sensation, image or idea, comes in the way, and
suppresses instantly this prolongation and echo. But in
many cases, and above all when the sensation has been
a prominent and important one, the image revives of
itself after a longer or shorter period of suppression. This
spontaneous revival is its fundamental property, and may
be effected after long periods have elapsed. Many of us
have recollections which go back twenty, thirty, forty
years, or more. I know a person, born in a little provincial
town, who can relate with the utmost exactitude all the
circumstances of a visit of the Empress Marie-Louise in
1811, can describe her dress, the dresses of the ladies and
young girls appointed to receive her, can hear mentally
the sound of her voice, see her gestures, her face, the
attitudes of the persons appointed to present her with an
address, and many other things. What renders these re-
vivals still more remarkable is that they frequently occur
without the image having reappeared during the whole in-
terval. On returning, after many years' absence, to one's
father's house, or to one's native village, numbers of forgotten
objects and facts unexpectedly re- appear. The mind, sud-
denly thronged by their stirring crowd, resembles a box of
dried rotifer a, which have lain inert some ten years, but when
sprinkled with water, at once revive and twist about. We
mount the dark staircase, we know where to find the handle
76
OF IMAGES.
[BOOK II.
of the door, we imagine ourselves seated at table in our ac-
customed place, we see the water-bottle on the right, and the
salt-cellar on the left, we seem to taste the flavour of some
Sunday dish. We look up at the wall and are surprised
not to find there some old engraving we had stared at as
children. We see the gesture and stoop of some former
guest, the square body and long folds of a blue dress ; we
almost hear the tones of voices which have long been still.
We come to the well, and recall the vague terror with which
as children, mounting on tiptoe, we looked on the obscure
depth and the trembling reflection of the cold water at
what seemed to us an infinite distance below.
Some people unconsciously preserve certain reviving
shreds of long-distant impressions. " There often recurred
to my mind," says M. Maury, " without my knowing why,
three proper names, each accompanied by the name of a
town in France. One clay I came across an old newspaper
and commenced to read it for want of anything better to
do. Among the advertisements I saw one of a depot of
mineral waters, with the names of the druggists who sold
them in the principal towns of France. There I found my
three unknown names with those of the three towns with
which they were connected in my mind. All was explained ;
my memory, which is excellent for words, had preserved a
recollection of these associated names, on which my eyes
must have rested while I was looking (as had happened
about two months previously) for the address of a depot of
mineral waters. But the circumstance had gone out of my
mind without the recollection being wholly effaced. Now,
certainly, I could not have paid much attention in so rapid
a glance."
Illness sometimes causes a revival of such images as this
of names, which seemed, not merely torpid, but hopelessly
extinct. " A girl was seized with a dangerous fever, and,
in the delirious paroxysm accompanying it, was observed to
speak in a strange language which, for some time, no one
could understand. At last it was ascertained to be Welsh
a tongue of which she was wholly ignorant at the time she
CHAP. II.] REVIVAL AND OBLITERATION OF IMAGES. 77
was taken ill, and of which she could not speak a single
syllable after her recovery. For some time the circumstance
was unaccountable, till, on inquiry, it was found that she
was a native of Wales, and had been familiar with the lan-
guage of that country in her childhood, but had wholly
forgotten it afterwards."* Again; some fugitive impres-
sions, not observed at the time, may rise anew with strange
power and automatic exactness. Many medical writers have
noticed the storyf of a young woman of five-and-twenty
who could neither read nor write, who, during an illness, re-
peated long passages of Latin, Greek, and Rabbinical
Hebrew, but on recovery, spoke nothing but her own lan-
guage. During her delirium, several of these fragments
were taken down in writing from her own mouth. After
inquiry, it was found that she had lived, when nine years
old, with her uncle, a clergyman of considerable learning,
who was in the habit of walking of an afternoon in a passage
adjoining the kitchen, and there reciting favourite passages
of Rabbinical Hebrew and Greek. On referring to his
books, there were found, word for word, many of the pas-
sages repeated by the sick girl. The noise and articula-
tion of his voice had remained fixed in her ears. She had
heard them as she repeated them without understanding
them.t Haschich, the death-agony, great and sudden
* Macnish, "Philosophy of Sleep," p. 55, n. ; and see two analogous facts cited
by Azam, " Anuales Medico-Psychologiques," 3 e Se'rie, vi. 443.
f Coleridge, "Biographia Literaria/' vol. i. p. 117.
J " A man of ordinary ability, servant of a Spanish ambassador, had frequently
to be present during important conferences, but did not appear to have recollected
anything of what had passed. He was seized with brain fever, and in his deli-
rium repeated with considerable order many discussions he had heard on the poli-
tical interests of different powers, so much so that the ambassador, who had con-
sidered him only as a faithful servant, came to hear him, and thought of promoting
him to be his secretary ; but the affection of the brain passed off, and when the
patient recovered, this memory had departed." (Grimaud de Caux, cited by Duval
Jouve, " Traite de Logique," 159.)
" I was once told by a near relative of mine, that having in her childhood
fallen into a river, and being on the very verge of death, .... she saw in a moment
her whole life, arrayed before her as in a mirror, not successively, but simulta-
neously ; and she had a faculty developed as suddenly for comprehending the whole
and every part." De Quincey," Confessions, &c." p. 258. tie Quincey and other
opium-eaters have observed in themselves this faculty of living mentally, during a
dream of a few minutes, a life of many years, and even of many centuries.
78
OF IMAGES.
[BOOK II.
emotion, sometimes cause revivals, equally minute, of sensa-
tions as little observed and still farther distant. We can
assign, then, no limits to these revivals, and are compelled
to ascribe to every sensation, however rapid, unimportant
or obliterated it may have been, an indefinite power of re-
vival, without mutilation or loss, even after an enormous dis-
tance of time ; just as a vibration of ether, which, starting
from the sun, transmits itself through millions of leagues
till it reaches our optical apparatus, with its special spectrum
and its proper rays, the same at its starting-point and at its
place of arrival, intact, and capable, by its exact conserva-
tion, of manifesting on the instrument receiving it the nature
of the fire from which it is emitted.
II. If, however, we compare different sensations, images,
or ideas, we find that their aptitudes for revival are not equal.
A large number of them are obliterated, and never reappear
through life ; for instance, I drove through Paris a day or
two ago, and though I saw plainly some sixty or eighty new
faces, I cannot now recall any one of them; some extra-
ordinary circumstance, a fit of delirium, or the excitement of
haschich would be necessary to give them a chance of revival.
On the other hand, there are sensations with a force of revival
which nothing destroys or decreases. Though, as a rule,
time weakens and impairs our strongest sensations, these
reappear entire and intense, without having lost a particle
of their detail, or any degree of their force. M. Brierre
de Boismont,* having suffered when a child from a disease
of the scalp, asserts that " after fifty-five years have elapsed
he can still feel his hair pulled out under the treatment of
the skull-cap'' For my own part, after thirty years, I
remember feature for feature the appearance of the theatre
to which I was taken for the first time. From the third row of
boxes, the body of the theatre appeared to me an immense
well, red and flaming, swarming with heads ; below, on the
right, on a narrow floor, two men -and a woman entered,
went out, and re-entered, made gestures, and seemed to me
* Brierre de Boismont, op. cit. 376.
CHAP. II.] REVIVAL AND OBLITERATION OF IMAGES. 79
like lively dwarfs : to my great surprise, one of these dwarfs
fell on his knees, kissed the lady's hand, then hid behind a
screen ; the other, who was coming in, seemed angry, and
raised his arm. I was then seven, I could understand
nothing of what was going on ; but the well of crimson
velvet was so crowded, gilded, and bright, that after a
quarter of an hour I was, as it were, intoxicated, and fell
asleep.
Every one of us may find similar recollections in his
memory, and may distinguish in them a common character.
The primitive impression has been accompanied by an
extraordinary degree of attention, either as being hor-
rible or delightful, or as being new, surprising, and out
of proportion to the ordinary run of our life; this it is
we express by saying that we have been strongly im-
pressed : that we were absorbed, that we could not think of
anything else ; that our other sensations were effaced ; that
we were pursued all the next day by the resulting image ;
that it beset us, that we could not drive it away ; that all
distractions were feeble beside it. It is by force of this
disproportion that impressions of childhood are so persistent ;
the mind being quite fresh, ordinary objects and events
are surprising. At present, after seeing so many large halls
and full theatres, it is impossible for me, when I enter
one, to feel swallowed up, engulfed, and as it were, lost in
a huge dazzling well. The medical man of sixty, who has
experienced much suffering, both personally and in imagi-
nation, would be less upset now by a surgical operation
than when he was a child.
Whatever may be the kind of attention, voluntary or in-
voluntary, it always acts alike ; the image of an object or
event is capable of revival, and of complete revival, in pro-
portion to the degree of attention with which we have con-
sidered the object or event. We put this rule in practice
at every moment in ordinary life. If we are applying our-
selves to a book, or are in lively conversation, while an
air is being sung in the adjoining room, we do not retain
it ; we know vaguely that there is singing going on, and
80
OF IMAGES.
II.
that is all. We then stop our reading or conversation, we
lay aside all internal pre-occupations and external sensations
which our mind or the outer world can throw in our way ;
we close our eyes, we cause a silence within and about us,
and, if the air is repeated, we listen. We say then that
we have listened with all our ears, that we have applied 1 our
whole minds. If the air is a fine one, and has touched us
deeply, we add that we have been transported, uplifted,
ravished, that we have forgotten the world and ourselves ;
that for some minutes our soul was dead to all but sounds.
And, in fact, there are numerous examples in which, under
the empire of a ruling idea, all other sensations, however
violent, are annihilated; such, for instance, is the story
of Pascal, who one night solved the problem of the cycloid,
to distract his mind from violent pain in the teeth ; that
again of Archimedes, who, in tracing geometrical diagrams,
was unconscious of the storming of Syracuse. Such also
are the frequent and well-proved instances of soldiers, who,
in the excitement of action, do not notice their wounds,
and those of ecstatics, of somnambulists, and of hypnotised
persons. These authentic instances, and these metaphors of
language, all bring to light the same fact, that is to say, the
more or less complete and universal cancelling of all sensa-
tions, images, or ideas in favour of a single one ; this last
one being persistent and absorbing, produced and prolonged
with an energy usually dispersed over several. In other
words, we are set up for a time in a fixed and determinate
form; the contrary solicitations, the different tendencies
which result in another state, the other images, ideas, and sen-
sations which are striving for production, remain in an inci-
pient and abortive state. The given form is incompatible with
them, and checks their development. What happens in us is
just what takes place in a solution when a crystal is formed ;
the particles which had no affinity for any special structure
now place themselves in a mass in fixed order; their un-
stable equilibrium is followed by a stable equilibrium whose
rigid and precise direction resists the different agitations of
the air and the fluid.
CHAP. II.] REVIVAL AND OBLITERATION OF IMAGES. 81
This exclusive momentary ascendancy of one of our
states of mind explains the greater durability of its aptitude
for revival and for more complete revival. As the sensation
revives in the image, the image reappears with a force pro-
portioned to that of the sensation. What we meet with in
the first state is also to be met with in the second, since the
second is but a revival of the first. So, in the struggle for life/*
in which all our images are constantly engaged, the one fur-
nished at the outset with most force, retains in each conflict,
by the very law of repetition which gives it being, the capacity
of treading down its adversaries; this is why it revives, in-
cessantly at first, then frequently, until at last the laws of
progressive decay, and the continual accession of. new im-
pressions, take away its preponderance, and its competitors,
finding a clear field, are able to develope in their turn.
A second cause of prolonged revivals is repetition itself.
Every one knows that to learn a thing we must not only
consider it attentively, but consider it repeatedly. We say
as to this in ordinary language, that an impression many
times renewed is imprinted more deeply and exactly on the
memory. This is how we contrive to retain a language,
airs of music, passages of verse or prose, the technical
terms and propositions of a science, and still more so
the ordinary facts by which our conduct is regulated.
When, from the form and colour of a currant jelly, we think
of its taste, or when tasting it with our eyes shut, we ima-
gine its red tint and the brilliancy of a quivering slice, the
images in our mind are brightened by repetition. When-
ever we eat, or drink, or walk, or avail ourselves of any of
our senses, or commence or continue any action whatever,
the same thing happens. Every man and every animal
thus possesses at every moment of life a certain stock of
clear and easily reviving images, which had their source in
the past in a confluence of numerous experiences, and are
now fed by a flow of renewed experiences. When I want
* "Struggle for Life" (Darwin). We shall see later on the development of this
doctrine. The theory of the great English naturalist is nowhere more precisely
applicable than in psychology.
a
82 OF IMAGES. [BOOK II.
to go from the Tuileries to the Pantheon, or from my
study to the dining-room,, I foresee at every turn the
coloured forms which will present themselves to my
sight; it is otherwise in the case of a house where I have
spent two hours, or of a town where I have stayed three
days ; after ten years have elapsed the images will be vague,
full of blanks, sometimes they will not exist, and I shall
have to seek my way or shall lose myself. This new pro-
perty of images is also derived from the first. As every
sensation tends to revive in its image, the sensation twice
repeated will leave after it a double tendency, that is, pro-
vided the attention be as great the second time as the first ;
usually this is not the case, for the novelty diminishing,
the interest diminishes; but if other circumstances renew
the interest, or if the will renovates the attention, the in-
cessantly increasing tendency will incessantly increase the
chances of the resurrection and integrity of the image.
III. These are but the general conditions of revival ; we
obtain them by comparing an image taken at any point
of its existence with another image at any point of its ex-
istence. We have now to compare two adjoining moments
in the same mind, and to determine the more special condi-
tions which excite at any time the birth of one image rather
than of another. For this, let us consider, not only isolated
sensations, but also series of sensations. These have a
similar tendency to revival, and the law which is applicable
to the elements is also applicable to the compounds. On
some days, without wishing it, we pass over in our mind
some portion of our life, such as a day's travel, some evening
at the opera, some interesting conversation. We feel our-
selves brought back in a fixed manner to a former state ; the
ideas which attempt to throw themselves in the way are
unwelcome ; they are driven out, or rest on the threshold ;
if, at the first moment, some gap was found in our recol-
lection, it usually ends by supplying itself; a forgotten
detail rises unexpectedly. I recollect at this moment an
evening spent at Laveno on the Lago Maggiore, and as I
dwell on it, I see my dinner at the inn, the coarse white
CHAP. II.] REVIVAL AND OBLITERATION OF IMAGES. 83
cloth, the pretty startled servant ; then, a moment after,
the path winding among thyme and lavender, the greyish-
blue lake under its moist cloud of vapour, the patches of
light, the glittering tracks, the sprinkled silver scales which
a stray sunbeam had embroidered in places on its level sheet,
the imperceptible rustling made by the little waves on the
shore, and the bells of the cows tinkling here and there in
the silence. All the prominent points in the group of sen-
sations I then had, reappear in turn or together. If now,
taking one of these points, I inquire how it emerged, I
find that it was when it had already commenced to emerge.
For instance, when I have recalled the winding lines of the
path, and imagine myself turning to the left, I recall the
slate- coloured lake and its embroidery of shining spangles,
and above, the peaked mountains descending in green slopes
to the water; I find that the extreme edge of the bank
borders the lake, the uniform surface is striped with bril-
liant fringes, and on the other side, the water rejoins the
meadows and rising slopes ; thus, the extremity of one image
coincides with the commencement of the next, and so the
latter begins to revive as the first disappears. In the
same way, the murmur of the tiny waves and the tinkling
of the bells revert to me when my visual images are those
of the lake and the bank ; a commencement of imaginary
sound accompanied the imaginary coloured forms ; it dis-
engages itself, and we feel it reproduced with all its
shades, and up to its end. The partial revival results in
a total revival. This is so true that if, upsetting the
natural tendency of the images to revert in the order of
the sensations, I attempt to reproduce the series inversely,
I am able to call up the former sensations from the latter
ones as soon as I can hit on the point of contact in which
they touch the ones they have followed. In fact, if I now
trace backwards up to my arrival at the inn, I see again
the old oak some twenty paces from the house, two or
three trunks of felled trees, and a dozen vagabonds strolling
about or sleeping in the warmth of the evening sun ; thus
by calling up the point of contact, that is to say, the com-
G2
84 OF IMAGES. [Boos II.
mencement of the image, I supply to the image the means
of reviving as a whole. In fact, to speak correctly, there
is no isolated and separate sensation. A sensation is a
state which begins as a continuation of preceding ones, and
ends by losing itself in those following it ; it is by an
arbitrary severing, and for the convenience of language, that
we set it apart as we do ; its beginning is the end of an-
other, and its ending the beginning of another. By force
of the general law which connects it to the image, its image
has the same properties as itself; therefore this image itself
arouses at its earlier extremity the ending of another
image, and at its later extremity the commencement of an-
other image, in such a way that the precedents and conse-
quents of the sensation have also indirectly their echo in the
image of the sensation.
Further than this, as different sensations are often similar
in part, as soon as the image of one among them appears,
the images of the others partially appear. When just now
I was describing the sparkling streaks which the sun made
on the water, I compared them to embroidery, to fringes,
and to spangles of silver ; the portion common to these
four sensations, present in the first, successively revived the
three others. Here again, the partial revival has resulted
in a total revival. We have often a difficulty in observing
this partial revival. It seems to us, at the first glance, that
such an idea has arisen involuntarily and by chance; we
cannot see how it is connected with the foregoing one. This
results from the idea which seems to have immediately pre-
ceded it, not having really done so ; there were intermediate
stages between them, which habit, inattention, or the speed
of the operation, have prevented our observing; these in-
termediate stages have served for an invisible transition, and
it has been through them that the law of Contiguity, or the
law of Similarity, has applied. Hobbes, one of the first
originators of this theory, relates* how, in the midst of a con-
versation on the English civil war, some one suddenly asked
" Leviathan," part i. ch. 3, vol. iii. p. 12 (Ed. Molesworth).
CHAP. II.] REVIVAL AND OBLITERATION OF IMAGES. 85
what was the value, under Tiberius, of the Roman penny;
an abrupt question seemingly unconnected with what had
gone before. There was, however, a connexion, and with a
little thought he recovered it. The Exiglish civil war, under
Charles the First, Charles the First delivered up by the
Scotch for 200,0007. sterling, Jesus Christ similarly be-
trayed for thirty pence under Tiberius. These were the
links of the chain which led the speaker to his remarkable
inquiry."^ We see now how the celebrated laws govern-
ing the association of images, and consequently that of
ideas, f are reduced to a more simple law. What excites
at any moment a particular image rather than any other, is
a commencement of the revival ; and this revival has already
commenced, either by similitude, from the anterior image or
sensation containing a portion of the reviving image ; or by
contiguity, from the anterior image becoming confused at its
end with the commencement of the reviving image. Given
any image at any particular moment, we can always explain
its actual presence by its commencement of revival in the
preceding image or sensation ; and its clearness, force, apti-
tude for revival and other intrinsic qualities, by the amount
of attention it has received, and number of revivals it has
undergone, either in itself or in the corresponding sensa-
tion. All, it will be observed, comprised in our funda-
mental law, which discovers the tendency to revival in the
sensation and in its image, and which, therefore, assures
to the commenced image, to the image accompanied by
* " An instance of this occurs to me with which I was recently struck. Think-
ing of Ben Lomond, this thought was immediately followed by the thought of the
Prussian system of education. Now, conceivable connexion between these two
ideas in themselves, there was none. A little reflection, however, explained the
anomaly. On my last visit to the mountain, I had met upon its summit a
German gentleman, and though I had no consciousness of the intermediate and
unawakened links between Ben Lomond and the Prussian schools, they were un-
doubtedly these, the German, Germany, Prussia, and, these media being ad-
mitted, the connexion between the extremes was manifest." Sir W. Hamilton,
"Lectures," &c., i. p. 353.
f See Bain, "Senses and Intellect." He derives all the operations of the intel-
lect from these two laws. See also Mervoyer, " lltude sur 1' Association des Idees"
(1864).
86 OF IMAGES. [BOOK II.
attention, and to the image strengthened by repetitions, a
preponderance which results in its revival.
IV. The same laws explain the opposite event ; by sup-
pressing or weakening the conditions which increase an
image's chance of revival and preponderance, we suppress
its chances of ascendancy and revival. In the first place,
all that lessens the attention lessens these chances. Every
minute we experience twenty sensations, of heat, cold, pres-
sure, contact, muscular contraction ; slight sensations like
these are being incessantly produced in all parts of our
bodies ; in addition to this, sounds, murmurings, and hum-
mings, are constantly going on in our ears ; a number of
little sensations of smell and taste arise in our noses and
throats ; but we are otherwise engaged we are thinking,
meditating, talking, reading and during all this time we
neglect other things. As regards other sensations, we are
as if asleep or in a dream ; the ascendancy of some dominant
image or sensation keeps them in a nascent state. If, at
the end of a minute, we attempt to recall them by memory,
they do not revive ; they are like seeds sown by the handful,
but which have not grown ; some single one, more lucky,
has monopolized to itself all the room and nutriment the earth
affords. It does not necessarily follow that these sensations,
destined to obliteration, are feeble ones ; they may be
powerful ones : it is sufficient that they should be weaker
than the privileged one. A musket-shot, the flash of a
cannon, a painful wound, frequently escape attention in
the heat of battle, and, not having been observed, cannot re-
vive ; a soldier suddenly finds he is bleeding, without being
able to recollect the blow he has received. In nine cases
out of ten, and perhaps in ninety-nine out of a hundred, the
sensation loses in this manner its power of revival, because
there cannot be attention without distraction, and the pre-
dominance acquired by one impression is a predominance
taken from the others. Here again, things are, as it were,
in a balance ; one scale can only rise by lowering the other,
and the lowering or elevation of the one is in proportion to
the elevation or lowering of the other.
CHAP. II.] REVIVAL AND OBLITERATION OF IMAGES. 87
On the other hand, the want of repetition also diminishes
the chances of revival. Every one knows that we forget
many of the words of a language when we have given up
reading or speaking it for many years. So it is with an
air we no longer sing, with a piece of verse we no longer
recite, with a neighbourhood we have been long absent from.
Breaks occur in the train of recollections, and go on increas-
ing like the holes in an old garment. We have no difficulty
in seeing how continuous and vast these destructions must
be; every day we lose some of our recollections, three-
fourths of those of the preceding day, then others among
those surviving from the previous month, so that before long
a whole month, or even year, is only represented in our
memory by certain prominent images, like those few peaks
still appearing in a submerged continent, destined, at least
the most of them, themselves to disappear, since the gradual
obliteration is owing to a continuous flood, invading one by
one the untouched crags, and sparing nothing but a few
rocks uplifted by some extraordinary circumstance to a
height no wave can reach. In fact, very few of our sensa-
tions, even of those accompanied by attention, are often re-
peated. Six months ago I was talking to such a person ;
after I left him, and even on the following day, I could
have described his appearance and dress, have repeated the
principal topics of conversation ; but since then I have not
renewed in experience or repeated in memory the images
which then revived in me, intact and connectedly. They
are obliterated, and now, when by chance I find some
fragment of the distant scene, and stop to call up the rest,
my efforts are vain. -So it happens with nearly all the
portions of our experience : the impression received has
been a solitary one ; in a thousand such, there is at most
one which is twice repeated ; in a thousand of the repeated
ones, there is scarcely one which is repeated twenty times.
Some few only those of permanent objects surrounding us
of some twenty or thirty persons, pieces of furniture, monu-
ments, streets, landscapes, derive from constant repetition a
multiplied aptitude for revival. With the others, the aptitude
88 OF IMAGES. [Boon II.
is too weak ; when a fragment of distant experience, with
which they were formerly connected, reappears, they do not
reappear with it ; the tendency which formerly called them
up is vanquished by other tendencies formed in the mean-
while; and the recent past blocks up the way of the earlier past.
Finally, on the other hand, images grow dull by repe-
tition, as bodies are worn away by friction. If we see a
person eight or ten times, the outline of his form and
expression of his face become at last much less clear in
our mind than on the day after we have first seen him. So
it is with a monument, a street, a landscape, when seen many
times at different hours of the day, at evening, in the morning;
on a dull day, in rain, under a bright sun, if we compare
them with the same monument, landscape, or street, watched
for three minutes, and then replaced by some entirely diffe-
rent object. The impression, so precise at first, becomes less
so the second time. When I imagine the monument, I
find indeed the outline, which has remained constant all
the time, but the distribution of light and shade, the changing
nature of the tones, the look of the grey or blackened
pavement, the band of sky above greyish and misty in the
one case, dark and tarnished in the other ; sometimes a
bright white, sometimes a dark purple in short, all the
diversities which at different moments have connected them-
selves with its permanent form, are mutually annulled. And
so, when I think of a person I know, my memory wavers be-
tween twenty different expressions, smiling, serious, unhappy,
the face bent on one side or the other. These different
expressions form obstacles to each other ; my recollection is
far clearer when I have only seen him for a minute when,
for instance, I have looked at his photograph or picture.
In fact, when the image of the form we have perceived
tends to revive, it draws with it the images of its several ac-
companiments. But these accompaniments being different
cannot revive together ; the features of the same face can-
not be at once smiling and severe ; the fa9ade of the same
palace cannot be at once of an intense black, as when the sun
is setting behind it, and of a rosy brightness, as when it is
CHAP. II.] REVIVAL AND OBLITERATION OF IMAGES. 89
rising in front of it. Therefore, if these mutually excluding
accompaniments have an equal tendency to revive, neither one
nor the other will do so, and we shall feel ourselves drawn in
different directions by contrary tendencies which come to
nothing; the images will remain in an inchoate state, and
will make up what we call in ordinary language an impres-
sion. This impression may be strong without ceasing to be
vague ; beneath the incomplete image a dull agitation is
going on, and as it were, a swarm of feeble impulses which
usually sum themselves up in an expressive gesture, a meta-
phor, a visible summary. Such is our usual state as regards
things we have many times experienced; a vague image,
corresponding to a portion of our different experiences,
a heap of contrary tendencies of nearly equal force, corre-
sponding to their different circumstances, a clear notation,
denoting and concentrating the whole in an idea.
This law of obliteration is of considerable extent, for it is
applicable not only to different appearances of the same
object, but also to different objects of the same class ; and
all the objects in nature may be grouped in classes. A
man who has passed through an alley of poplars, and wishes
to figure to himself a poplar, or who, after seeing a large
farmyard, wishes to figure to himself a hen, experiences a dif-
ficulty. His different recollections encroach upon each other ;
the differences which distinguished the two hundred poplars
or the hundred and fifty hens are mutually obliterated ; he
will preserve a more precise image if he has only seen a
single poplar standing in a meadow or a single hen roosting
in a shed. All our images undergo a similar blunting ; let
the reader attempt to imagine a rabbit, a carp, a pike, a bull,
a rose, a tulip, a birch tree, or any other object belonging
to a numerous class and of which he has seen many indi-
viduals, and on the other hand, an elephant, a hippopotamus,
a magnolia, an American aloe, or any other object of a
small class, and of which he has only met with one or two
specimens ; in the first case the image is vague and all its
surroundings have disappeared ; in the second it is precise,
and one is able to point out the spot in the Jardin des
90 OF IMAGES. [BOOK II.
Plantes, the Parisian Conservatory, the Italian villa, where
the object was seen. The multiplication of experience is then
a cause of obliteration, and images, by annulling one an-
other, thus fall into the state of dull tendencies hindered by
their contrariety and equality from assuming an ascendancy.
V. Thus we arrive at a general conception of the his-
tory of images, and, consequently, of ideas in a human
mind. Every sensation, weak or strong, every experience,
great or small, tends to revive by means of an internal
image which repeats it, and is itself capable of repeating,
even after long pauses, and this indefinitely. But as sensa-
tions are numerous, and are at every moment replaced by
others, without truce or termination, up to the end of life,
there is a conflict of preponderance between these images,
and, though all tend to revive, those alone do so, which have
the prerogatives required by the laws of revival ; all the others
remain incomplete or null, according to the laws of oblite-
ration. By force of this double law, groups of efficacious
aptitudes are constantly becoming inefficacious, and images
are falling from the state of actual to that of possible exis-
tence. Thus, human memory is like a vast reservoir, into
which daily experience is continually pouring different streams
of tepid waters ; these waters being lighter than the others
rest on the surface and cover them ; then growing cold in
their turn, they descend to the bottom by portions and degrees,
and it is the last flow that constitutes the new surface.
Sometimes a particular stream, from being swollen or having
a higher fall, warms ancient inert layers below, and then
they remount to the light ; the chance of the flow and the
laws of equilibrium have warmed a certain layer so as to
place it above the rest. The shape of the reservoir, the
accidents of temperature, the various qualities of the water,
sometimes even shocks of earthquake, all bear part in this ;
and many authentic instances show us deep layers uplifted
suddenly and entire to the surface, sometimes superficial
layers plunged suddenly and entire below.
In fact, images have, as we shall see later on, certain
states of brain as conditions of their being ; hence, we
CHAP. II.] REVIVAL AND OBLITERATION OF IMAGES. 91
understand how an injury, a rush of blood, a deteriora-
tion of blood, any change of the cerebral substance, may
hinder or promote the arising of certain groups of images.
" I descended on the same day," says Sir Henry Holland,*
" two very deep mines in the Hartz mountains, remaining
some hours underground in each. While in the second
mine, and exhausted both from fatigue and inanition, I felt
the utter impossibility of talking longer with the German
inspector who accompanied me. Every German word and
phrase deserted my recollection, and it was not until I had
taken food and wine, and been some time at rest, that
I regained them.'" Similar mischances are not uncommon
after brain fevers or great losses of blood. A lady, says
Winslow, f after large uterine haemorrhage, " had forgotten
where she lived, who her husband was, how long she had
been ill, the names of her children, and even her own
name. She was unable to give anything its real name, and
in attempting to do so, made the most singular mistakes.
She had been accustomed, before her illness, to speak
French instead of English. But afterwards she seemed to
have lost all knowledge of French ; for, when her husband
addressed her in that language, she did not appear to under-
stand what he said the least in the world, though she could
converse in English without difficulty/' After seven or
eight weeks these blanks in her memory began to be
restored; and after some months they were entirely filled
up. So a gentleman, mentioned by Abercrombie, " after
a blow on the head, lost his knowledge of Greek, and did
not appear to have lost anything else."J The loss occa-
sionally attaches to some period of former life. " A clergy-
man, on recovering from an apoplectic attack, was found to
have lost the recollection of exactly four years; everything
that occurred before that period he remembered perfectly.
He gradually recovered." Another patient, who had been
* " Chapters on Mental Physiology," p. 167, n. cited by Winslow, "Obscure
Diseases," &c., p. 252.
f Winslow, ibid. p. 344.
$ "Inquiry into the Intellectual Powers," p. 152. Ibid. p. 151.
92 OF IMA GES. [Boos IT.
for some ten or twelve years in Edinburgh, recollected
nothing of that period of his life ; on the contrary, the
earlier portion, which had been passed in another country,
was well remembered by him. Lately, a celebrated Russian
astronomer forgot, in turn, the events of the previous day,
then those of the year, then those of the years last past,
and so on, the chasm gradually increasing, till at last he
could only recollect the events of his childhood. His case
was considered hopeless ; but by a sudden stop and unfore-
seen return, the blank filled up in an inverted manner ; the
events of his youth first reappearing, then those of his man-
hood, and finally, the more recent, those of the previous
day. His memory was wholly restored at the time of his
death.
Gradual recoveries like these have also been observed
after violent falls ; and the fissure in the memory closes
up sometimes from one end, sometimes from the other.
" Some years ago," says Abercrombie,* " I saw a boy
who had fallen from a wall, and struck his head against a
stone which lay at the foot of it. He was carried home in
a state of insensibility, from which he soon recovered, but
without any recollection of the accident. He felt that his
head was hurt, but he had no idea how he had received the
injury. After a short time he recollected that he had been
on the top of a wall, and had fallen from it and struck
against the stone, but could not remember where the wall
was. After some time longer, he recovered the recollection
of all the circumstances/'' Others when injured forget
the accident only, and not the circumstances ; others the
circumstances only, but not the accident. Sometimes the
alteration is still stranger, and affects a certain class of
associations only. "A lady,f after an apoplectic attack,
recovered correctly her ideas of things, but could not name
them. In giving directions respecting family matters, she
was quite distinct as to what she wished to be done, but
could make herself understood only by going through the
Inquiry into the Intellectual Powers," p. 146. f Ibid. p. 149.
CHAP. II.] REVIVAL AND OBLITERATION OF IMAGES. 93
house, and pointing to the different articles. A gentleman
could not be made to understand the name of an object if
it was spoken to him, but understood it perfectly when it
was written. His mental faculties were so entire that he
was engaged in most extensive agricultural concerns, and
he managed them with perfect correctness by means of a
remarkable contrivance. He kept before him in the room
where he transacted business, a list of the words which
were most apt to occur in his intercourse with his work-
men. When one of these wished to communicate with
him on any subject, he first heard what the workman had
to say, but without understanding him further than simply
to catch the words. He then turned to the words in his
written list, and whenever they met his eye he understood
them perfectly."*
This suppression of ordinary aptitudes explains the revival
of lost aptitudes. One particular new organic disposition
may be unfavourable to the first ; and so, some other new
organic disposition may be favourable to the second. The
first cease to be active, like a nerve suddenly paralysed;
the second become active again, like a paralysed nerve sud-
denly electrified. We have seen an instance of this in the
case of the ignorant young girl who, in her delirium, recited
* See other analogous facts in the " Dictionnaire d'Histoire Naturelle," pub-
lished by M. Gruerin, in an article by Grimaud de Caux. (Duval Jouve, " Logique,"
p. 159.)
" A man of sixty, in good health, who had had an ulcer in his leg for a con-
siderable time, permitted it to become closed. Before long he had a slight attack
of apoplexy, and this was followed by a loss of memory, first of certain words,
then of the French language. The remarkable thing was that he recollected per-
fectly the Piedmontese language.
" A man of science on starting for Greece was thrown out of his carriage ; a
box, fortunately not a very heavy one, fell on his head ; he suffered no pain, and
the skin was not broken ; but he completely forgot where he had come from, the
object of his journey, the day of the week, the dinner he had just made, and all
his acquired knowledge. In fact, he had forgotten the names of his relations and
friends, and could only recall his own, those of his children, and the symbol of the
Trinity. He was replaced in the carriage, in order that assistance might be ob-
tained, and, after half an hour's jolting over a stony road, suddenly recovered
himself."
Page 162 " Some persons forget proper names ; others, like Doctor Brousson-
nais, substantives. Dietrich tells the story of a man who, while recollecting facts,
had forgotten half his words. There are instances of foreign languages, the facts
of history, dates, &c., being entirely forgotten, while other things were recollected."
94 OF IMAGES. [BOOK II.
passages of Greek and rabbinical Hebrew ; in the servant
who, when seized with fever, spoke Welsh, which, when
well, she did not understand. " A man," says Abercrombie,
" born in France, had spent the greater part of his life in
England, and for many years had entirely lost the habit
of speaking French. When under the care of Mr. Aber-
nethy for an injury of the head, he always spoke French."*
In other cases a similar revival as to other languages has
been observed. "An eminent medical friend," says the
same author, " informs me that during fever, without
any delirium, he on one occasion repeated long passages
from Homer, which he could not do when in health/ 7
Another person, who, when well, had no capacity for
music, and had almost forgotten the Gaelic language, sang,
during an illness, Gaelic songs, and that with great preci-
sion, though the melody was a difficult one, and he had
previously been utterly incapable of singing it.
Let us now conceive the existence in the same person
of two distinct states, such as we have been describing ; let
us suppose that in the first a certain group of images, in
the second, some other group, can alone revive, what will
happen if in the two states the general organic disposition
is different, and if this difference is a clearly marked one ?
The individual will have two memories, the first recalling
only the events of the first state, and the second recalling
only the events of the second state. f A young American
lady, says Macnish,J after a prolonged sleep, lost the recol-
lection of all she knew. She was obliged to learn again
how to spell, to read, to write, to calculate, and to know
the persons and objects around her. A few months after,
* Abercrombie, op. cit. 140, 142.
t "When people have been twice hypnotised, we find that they forget completely
when they wake the acts and thoughts artificially produced, and recover perfect
recollection of them on re-entering the artificial state. Mr. Braid mentions having
seen intelligent persons who could recollect exactly and minutely all tbat had
happened during a state of sleep six years before, and who narrated this when-
ever they were hypnotised, while, when awake, they had no recollection of it."
"De la Folie Artificielle," Dr. Tuke, " Annales Medico-Psychologiques ," 4 e Serie,
vi. p. 271.
Macnish, p. 113, n. citing from " The Medical Repository." New York.
CHAP. II.] REVIVAL AND OBLITERATION OF IMAGES. 95
she was again seized with a deep sleep, and when she woke
she was restored to the state she was in before the first
sleep, having all the knowledge and recollections of her
youth ; but on the other hand, having entirely forgotten all
that had passed between the two attacks. " During four
years and upwards she has passed periodically from one
state to the other, always after a long and sound sleep
The former condition of her existence she now calls the Old
State, and the latter the New State ; and she is as uncon-
scious of her double character as two distinct persons are of
their respective natures. For example, in her old state she
possesses all the original knowledge ; in her new state only
what she acquired since. If a lady or gentleman be intro-
duced to her in the old state, or vice versa (and so of all
other matters), to know them satisfactorily she must learn
them in both states. In the old state, she possesses fine
powers of penmanship, while in the new, she writes a poor
awkward hand, not having had time or means to become
expert. Both the lady and her family are now capable of
conducting the affair without embarrassment. By simply
knowing whether she is in the old or new state, they regu-
late the intercourse, and govern themselves accordingly/'
This double life is often found in somnambulists.* The
majority of them forget on awaking all they have done in
their sleep, and are surprised to find themselves out' of bed
or in the street. But this forgetfulness frequently ceases
on a second attack. " The somnambulist/'' says M. Maury,
" takes up again the chain of ideas interrupted while he was
awake. Thus Dr. Mesnet's patient carried out, during an
attack, projects of suicide she had conceived in a previous
attack and forgotten during the lucid interval ; in the second
attack she recalled all the circumstances of the first.
M. Macario has cited a very significant example of a
young girl who was violated during a fit of somnambulism,
* Maury, "Du Sommeil," 210. Todd, " Cyclopaedia," Article "Sleep." Puel,
Memoire sur la Catale^sie.'*
96 OP IMAGES. [BOOK II.
and who, on awaking, had no recollection or consciousness
of what had happened. It was only in a new fit that she
related to her mother the outrage committed upon her."
In these two instances, the wakeful state only recalled the
wakeful state ; the state of somnambulism only recalled the
state of somnambulism,, and each of the two alternate lives
formed a separate whole.
Correspondences and separations like these, hut partial
and temporary, are met with in ordinary life. " Mr. Combe
mentions the case of an Irish porter to a warehouse, who, in
one of his drunken fits, left a parcel at the wrong house,
and when sober could not recollect what he had done with
it; but the next time he got drunk, he recollected where
he had left it, and went and recovered it."* M. Maury
again mentions cases of dreams forgotten when awake, and
recalled in a new state of sleep. On the other hand, our
ordinary memory recalls only half our states. We recall our
thoughts of yesterday, but not those of the night while we
were asleep ; however vivid they may have been, even when
they have provoked actions or the beginnings of actions,
cries, gestures, and all that an uneasy man does in his sleep,
it is very unusual for us to be able on waking to recover
any portions of them.f It is a strange thing, we start
from an intense dream, full of emotions ; and it would seem
that so violent a state ought to be easily reproduced, even
after a considerable time. Not at all ; after two or three
minutes the objects so clearly perceived die away in clouds ;
and these clouds vanish ; half an hour afterwards I shall
be scarcely able to relate my dream ; if I want to remember
it later on, I am obliged to write it down at once. The
fact is that the physiological state and the circulation of blood
in the brain are not alike in sleep and when awake, and the
second state, favourable to the recall of its own images, is
not favourable to the recall of the images of the first
state.
But whatever be the phenomenon, rudimentary and normal,
* Macnish, ibid. p. 55, n. f Macnish, ibid.
CHAP. II.] REVIVAL AND OBLITERATION OF IMAGES. 97
or abnormal and complete, it shows how our images, by
connecting themselves, make up the group which in literary
and judicial language we call the moral personality. If
two groups are distinctly severed, so that no element of the
one calls up any element of the other, we shall have, as in
the case of the lady cited by Macnish, two moral persona-
lities in the same individual. If in one of the two states
the images have exact and delicate associations, if, as we
see in the cases of many somnambulists,* superior aptitudes
show themselves, if, as we observe in drunkenness and
after many illnesses, the passions take another degree and
another direction, not only will these moral personalities be
distinct, but there will be enormous disproportions and
contradictions between them. No doubt, though among
somnambulists, persons hypnotised and in states of ecstasy,
similar contrasts distinguish the ordinary from the ab-
normal life, these two lives are not clearly nor entirely
distinct ; some images of the one always, or nearly always,
introduce themselves into the other ; and, when man is
concerned, the supposition we have made remains simply
a conception of the mind. But, among animals, we meet
with instances in which it is exactly applicable; such as
that of the batrachians, and of insects which undergo meta-
morphoses. Their organization and nervous system bring
forward in turn, by their transformations, two or three
moral personalities in the same individual : in the chrysalis,
the larva, and the butterfly, instincts, images, recollections,
sensations, and appetites, are all different ; the silkworm
which spins, and its moth which flies, the voracious larva of
the cockchafer, with its terrible apparatus of stomachs,
and the cockchafer itself, are two distinct states of the
same being at two epochs of its development, two distinct
systems of sensations and images engrafted on two dis-
tinct forms of the same nervous substance. If a sleep like
that of the chrysalis were to overtake us in the midst of
our life, and if we were to awake with an organization
* Maury, ibid. p. 125.
)F IMAGES.
[BOOK II.
and a nervous machinery as much transformed as that of
the worm which has become a butterfly, the break between
our two moral personalities would evidently be as great in
our case as with it. The reader can now see the infinite
consequences of that property of our sensations and images
which we have termed aptitude for revival ; it assembles in
groups our internal events, and in addition to the conti-
nuity of physical being constituted by permanence of form,
it constitutes, by the return and connexion of images, the
continuity of the moral being.
CHAP. I.] SENSATIONS OF HEARING, < THEIR ELEMENTS.
BOOK III.
OF SENSATIONS.
CHAPTER I.
OF SENSATIONS OF HEARING AND THEIR ELEMENTS.
I. BY reduction upon reduction we have arrived at a
fact, primitive and apparently irreducible, of which all the
rest, whether images or ideas, are but repetitions more or
less transformed and disguised. I mean sensation, and
before denning it, that is to say, before showing its nature,
we must first describe it, that is, must distinguish it and
bring it to light, from among the heap of facts in which it
is comprised. When a cutting instrument is plunged into
our flesh, we feel pain, and this pain, taken by itself and
alone, is a sensation strictly so-called. There are a number
of such facts, similar in nature, though differing in kind and
degree ; such are the sensations of contact, of pressure, of
tickling, usually excited in us when an external body touches,
in a particular way, certain portions of our bodies ; such are
the sensations of temperature produced when a certain
degree of heat is added to or taken away from our ordinary
temperature ; such are the sensations of muscular activity, so
called from their apprising us of the tension or relaxation
of our muscles ; such, in short, are the sensations excited iii
us by the particular juices of an object we taste, by the vola-
tile particles of an object we smell, by the vibrations of the
air which strike our organs of hearing, by the vibrations of
light which strike our organs of sight, and which we com-
monly call sensations of taste, of smell, of sound, and of
colour.
H 2
100 OF SENSATIONS. [BOOK III.
Many of these names are ambiguous, and the words
taste, smell, sound, colour, heat, sometimes denote a pro-
perty, more or less unknown to us, of surrounding bodies,
of liquid or volatile particles, of vibrations of the air or of
light; sometimes, the well-known kind of sensations which
these bodies, particles, and vibrations, excite in us. But the
distinction is 'easily made; for the property appertains to
the object and not to us, while the sensation appertains to
us and not to the object. Lemon-juice has an acid taste ;
this means that it possesses an unknown property of exciting
in us a well-known sensation, that of an acid taste. This
sheet of paper is white : this means that by virtue of its
particular texture, this sheet of paper, when in the light,
excites in us the sensation of the colour white. Two
other distinctions less readily made are no less necessary.
When we experience a sensation, we localize it ; we refer
such a pain, such a feeling of heat, such a sensation of
contact, to the hand, to the leg, to such-and-such a part of
the body, such a sensation of smell to the interior of the
nose, such a sensation of taste to. the palate, to the tongue,
to the back of the mouth. But, as we shall see later on,
there is here an ulterior operation engendered by expe-
rience ; a group of images has combined with the sensation
to attribute to it this position ; this group gives it a situa-
tion which really it has not, and, in general, places it at the
extremity of the nerve whose action excites it. Sometimes
again, a second operation removes it to a still more distant
place ; sounds and colours, which are sensations only, at
present appear to us situated, not in our organs, but at a dis-
tance, in the air, or on the surface of external objects ; the
reader will see, when we examine external perception, how
the education of the senses produces this apparent recoil.
Meanwhile, to understand the sensation properly, we must
separate it from this accompaniment, must lay aside the
appendages which time has attached to it, and consider it in
its simple primitive state. Finally, we must distinguish it,
at least provisionally, from the state of the nerve and nervous
centres by whose action it is produced. It is true that this
CHAP. I.] SENSATIONS OF HEARING, & THEIR ELEMENTS. 101
state is the sufficient and necessary condition of the sensation,
but their identity is not clear ; at first sight they differ, and
certainly are not known to us to the same extent or in the
same way. For the sensation is perceived directly, com-
pletely, and at once, but the action of the nervous system is
proved indirectly, incompletely, and very slowly ; an infinite
amount of anatomical and physiological research was re-
quired to teach us that the sensation depended on it; even
now we are wholly ignorant of what it consists, whether it is a
propagated vibration, an electric current, a chemical change,
or what else it may be. Strict method then requires us, for the
present, to leave it on one side and to study in the first place
the sensation apart. So circumscribed, it is that primary in-
ternal event, directly known to us, accompanied by images
associated with it and localizing it, and excited by a certain
state of the nerves and nervous centres, a state unknown to us,
and consequent, in general, on the action of external objects.
II. Here we have a fact of supreme importance ; for its
diversities and arrangements form the material of all our
knowledge. When we consider closely any one of our con-
ceptions that of a plant, an animal, a mineraJ. we find
that the primitive threads of which it is woven are sen-
sations, and sensations only ; we shall see the proof of this
later on. But we have it already, if we recollect that our
images are only reviving sensations, that our ideas are no-
thing more than images which have become signs, and that
thus this elementary tissue subsists, in a more or less dis-
guised form, at all stages of our thought. These primitive
threads are of different kinds. Sensations have long been,
more or less happily, distributed, in the ordinary method,
into classes and sub-classes ; first, according to the ser-
vices they render us ; then, according to the particular
circumstances iu which they arise, and the parts in which
the associated images induce us to place them ; and lastly,
according to such rough similarities as internal observation
can find in them * A first group has been formed of those
* Gerdy, " Physiologic des Sensations et de 1' Intelligence." Bain, "Senses
and Intellect," 87, 250.
102 OF SENSATIONS. [BOOK III.
which denote different states of the body in health or
sickness, and are stimulants to action, rather than ele-
ments of knowledge ; these have been called sensations
of organic life, and have been divided into genera and
species, according to the organs or functions which excite
them ; in one class, effort, fatigue, and the different pains
occasioned by states of the muscles, bones, and tendons ; in
another, nervous exhaustion, and the nervous sufferings
occasioned by special states of the nerves; in another, the
sufferings of thirst and hunger occasioned by certain states of
circulation and nutrition ; in another, suffocation and the
peculiar state of uneasiness occasioned by a certain state of
the respiration ; in another again, sensations of cold and
heat occasioned by a general state of all the organs ;
finally, in another, those, as of digestion, occasioned by
states of the alimentary canal. By the side of this group
a second has been formed, whose earlier classes come in
contact with the latter ones of the first group ; it comprises
those sensations which do not acquaint us with the healthy
or unhealthy states of our bodies, but are elements of
knowledge, rather than stimulants to action. These we call
sensations of intellectual life, and divide them, according
to the special organs exciting them, into sensations of smell,
of taste, of touch, of hearing, and of sight. In each of
these genera there are species. In sensations of taste, dis-
tinctions are drawn between relishes* allied to alimentary
sensations, and provoking appetite or disgust, according to
the state of the stomach, and tastes strictly so called, and
themselves divisible into many groups, such as bitter, sweet,
salt, alkaline, acid, astringent. In sensations of smell,
distinctions are similarly drawn between smells connected
with the respiratory sensations, compounded or mingled with
a sensation of freshness or closeness, and smells strictly so
called, and themselves divisible into perfumed, foetid, pungent,
ethereal, &c. Similar classifications are adopted in the dis-
tribution of the sensations of the other senses; and slight
* Relishes distinguished from tastes. Bain, <: Senses and Intellect. 1
CHAP. I] SENSATIONS OF HEARING, & THEIR ELEMENTS. 103
differences will be found in them, according to different
authors.*
But these differences are of little importance ; all they
afford us is a survey of the subject; we have constructed
a convenient repository, with compartments enabling us to
lay our hands readily on the sensation we wish to consider ;
but this is all. We do not know what the sensation
itself consists in ; if we consider some particular one for
instance, the smell of a rose we find it comprised in the
class of perfumed odours with that of the lily, the violet,
musk, and an infinite number more. But while thus
distinguishing it from others, we cannot say in what it
differs from them ; we vaguely perceive that it is a stronger
smell than that of the violet, and not so strong as that of
the lily ; our knowledge is reduced to this. We cannot
enumerate and state its elements as precisely as if it were
a question of two kinds of minerals or vegetables ; we have
no elements of comparison, like magnitude, form, position,
number, to sum up and connect together; mathematical
and geometrical qualities, which serve as a foundation for
the physical sciences, fail us here. And here, again, the
ground from which we started to construct the moral
sciences fails us also. We have not here those common
elements, images, representations, general ideas, to which
different human inventions and social combinations may be
reduced. We are at the central point of knowledge, a kind
of link placed between the infinite ramifications of the
branch and those of the root, enclosing in its narrow band the
origin of the fibres which above and below make up, by their
multiplication and their arrangement, the entire plant.
But it is precisely because our sensations are elements of
which all the rest is composed, that we are unable to de-
compose them like the rest ; we cannot find elements of
these elements. We are able to show how with them we
form images, representations, and general ideas how with
them we form notions of magnitude, position, form, and
* See the physiological works of Longet, Mueller, Carpenter, Todd and
Bowman, &c.
104 OF SENSATIONS. [BOOK III.
number ; but as to bow tbey are themselves formed,, this we
do not know.
It seems, then, that they escape from science ; and, in
fact, when we read works treating of them, we learn little
but what we knew before ; when we close the book, we find
them well arranged in our mind, and that is all. If we are
taught anything, it is in another department, in physiology
and anatomy, by the knowledge of the apparatus, organs,
and movements on which they depend. Even with the highest
hopes, all the horizon shows us is a more extended know-
ledge of these apparatus, movements, and organs ; perhaps
some day, if the microscope becomes more powerful, when
the theories of electricity, organic chemistry, and molecular
physics have made some great advance, experimentalists
may be able to distinguish the different primitive fibres in a
nerve, may define exactly their internal movements, explain
the structure of the nervous centres, and state precisely
what change of state the action of the nerve excites there.
Under the most favourable circumstances, and supposing the
science complete, we should arrive at a mathematical for-
mula enabling us to sum up in some one law the different
positions and relations of the nervous particles. But these
advances, great as we imagine them to be, add nothing to
our idea of sensations ; they enlighten us as to their condi-
tions, but not as to them. If you describe to me the mole-
cular movement produced in the glosso-pharyngeal nerves,
and the other molecular movements consequently developed
in the nervous centres when a solution of sugar or of colo-
cynth passes over my tongue or throat ; you will not teach
me anything as to the nature of the sensations of sweet and
bitter. I shall know the circumstances under which they
arise, I shall not know their elements, or even if they have
any. The most I shall perhaps find will be some law con-
necting the intensity of bitterness with some form or other
of molecular movement, resembling the law which makes
the acuteness of a sound increase with the number of vibra-
tions transmitted to the auditory nerve.
The matter becomes still clearer when we compare two
CHAP. I.] SENSATIONS OF HEARING, & THEIR ELEMENTS. 105
sensations, not of the same, but of different senses, even
when both are produced by the same external cause; for
instance, the tickling and the sound produced by the same
vibrations of the air, the painful feeling and luminous circle
produced by the same compression of the eye, the sensations
of dazzling light, of hissing sound, of shock, or tingling,
produced by the same electricity applied to different senses*
Each one of these senses forms a region apart; neither
smell, nor taste, nor colour, nor sound, nor sensation of
contact, can be reduced to any other ; and, in every sense,
there are many regions no less distinct from one another ;
bitter, salt, and sweet tastes, like blue, red, and yellow
colours, like sensations of heat, pressure, and tickling, seem
equally irreducible to one another. The only intrinsic
quality which we find to be common to all these distinct
domains, is the degree of intensity; every sensation is
capable of increase or decrease ; it is a stage in a magni-
tude; smell, taste, sound, brightness, pressure, may all be
more or less strong. So it is with the secondary groups
comprised in the principal ones; every special sensation,
that of bitterness, of tickling, of blue, has a maximum and
a minimum, on passing which, it ceases, or becomes of an-
other kind. But each of them is a kind of simple body
which, though capable in itself of increase or diminution>
is not convertible into any of the others. In chemistry
there are sixty- one such; there are many more for every
sense, for instance, for smell or taste; for there is scarcely
a single volatile odorous matter that does not form a type
apart ; we are sometimes able to arrange two, or at most
three other sensations, together with the sensation it excites,
as the smell of garlic and of the vapour of arsenic with the
smell of tin ; thus the species are innumerable, and classes
scarcely exist; as we see on attempting to count the smells
of perfumed plants in a garden, or of disagreeable gases in
a laboratory. Thus it would seem that at the commencement
of psychology, we are obliged to set down a very great number
of facts as mutually irreducible, just as simple bodies in
chemistry, as the species of animals in zoology, or of vege-
106 OF SENSATIONS. [BOOK III.
tables in botany, but with this special disadvantage, that
while in chemistry, in botany, and zoology, differences and
resemblances are constituted by homogeneous and precise
elements, number, force, and form, in the sensations, no
such element can be isolated, and we are driven to the unrea-
soning affirmation of certain rough likenesses and to the
dry statement of an indefinite number of undefinable dif-
ferences.
III. Sensations, however, have elements, as will appear
from various examples. We all know that in a musical
chord there are two notes, that an ordinary colour is made
up of many colours ; we must advance a step, and see if
those sensations of sound, colour, and the rest, which
appear to us simple, are not themselves composed of more
simple sensations. Psychology is at present confronted
with sensations professedly simple, just as chemistry was,
at its outset, with professedly simple bodies. In fact,
in its early stages, observation, whether internal or exter-
nal, perceives compounds only; its business is to decom-
pose them into their elements, to show the different group-
ings these elements are capable of, and to construct diffe-
rent compounds with them. The chemist shows that, by
the combination of a proportion of nitrogen with one, two,
three, four, or five, proportions of oxygen, we form protoxide
of nitrogen, deutoxide of nitrogen, nitrous acid, hyponitric
acid, and nitric acid; five substances which, to ordinary
observation, have nothing in common, and which, neverthe-
less, differ only in the number of proportions of oxygen
comprised in each of their atoms. The psychologist has
to inquire whether, by combining such-and-such an ele-
mentary sensation with one, two, three, other elementary
sensations, by approximating the times of their occurrence,
by giving them a longer or shorter duration, by communi-
cating to them a greater or less intensity, he cannot arrive
at constructing those masses of sensation to which rude
consciousness attains, and which, though irreducible to her,
differ only in the duration, proximity, magnitude, and
number of their elements.
CHAP. I.] SENSATIONS OF HEARING, & THEIR ELEMENTS. 107
Now there is a group of sensations in which a complete
reduction can be effected namely,, those of hearing ; and
we may legitimately argue from these to others; the
partial solution attained indicates a general solution which
may be attained. The kinds of sounds are apparently very
numerous ; and ordinary observation detects in them many
seemingly simple qualities. Two sounds produced by the
same instrument may be respectively high and low. Two
sounds equally high or low have different tones, if produced,
one by a violin, and the other by a flute. Two sounds
equally high or low, and of the same tone, may be more or
less loud or intense. Two sounds may be, the one musical,
the other unmusical ; that is to say, the one may be a con-
tinuous sensation, all whose parts are mutually alike ; while
the other is a discontinuous sensation, and made up of
parts differing from one another. Finally, this last class
contains many kinds apparently irreducible to one another ;
explosions, clangings, grindings, hummings, rustlings, which
we can only denote by the body and external condition
producing them, as the sound of a hammer, of a glass, of a
piece of wood, of crumpled paper, &c. In this great col-
lection we distinguish two qualities capable of degrees in-
tensity, and acuteness ; in these respects, different sounds
form a scale ; in all other respects, they are in juxta-
position, are vaguely related to one another, like smells
and tastes, without it being possible to say in what this
relationship consists ; tone, for instance, like noise, is a
thing undefinable. The same sol played with the same
strength on a clarionet, a flute, a violin, a horn, a bas-
soon, borrows a special character according to the different
instruments ; it is more piercing on the violin, more bril-
liant on the horn, sweeter on the flute, keener on the
clarionet, more veiled on the bassoon. But none of
these adjectives define it ; they only indicate some distant
analogy between our total impression and impressions of
another nature ; they are simply literary labels like the
names we apply to perfumes, when we call the smell of the
heliotrope delicate, that of the lily, full and rich, of
108
OF SENS A TIONS.
[Boos III.
musk,, penetrating, &c. These epithets tell us something
of our sensation, but very little ; in no case do they tell us
anything of the elementary sensations, of which our whole
sensation is made up.
Fortunately, students of physics and physiology have
advanced our researches while pursuing their own ; and
their discoveries as to undulations and the nerves enable
us to find what we are seeking. The sensation of sound
is excited by the concussion of the acoustic nerve, occa-
sioned, in most cases, by the vibration of the external air ;
we further observe, in fact, that when precisely similar
concussions are occasioned, precisely similar sensations of
sound are produced. This is the case with the sirens of
Cagniard Latour and Helmholtz, and the wheel of Savart.
When this wheel is turned at an uniform rate, its teeth,
which are at equal distances, strike a bar in passing; and
this regular succession of similar concussions excites a
regular succession of similar sensations of sound. Now,
while the wheel turns sufficiently slowly, the sensations, being
discontinuous, are distinct ; and each of them, being com-
pound, is a sound. But when the wheel is set to turn fast
enough, a new sensation arises, that of a musical note. It
distinguishes itself from the remains of the noises which
still go on and continue distinct, and stands out as a fact
of a different kind ; among the different elementary sensa-
tions which make up each sound, there is one which the
operation has separated ; and this now ceases to be distinct
from the similar elementary sensation following in each of
the succeeding sounds. All these similar sensations now
combine in one long continuous sensation ; their mutual
limits are effaced; experience, just as in a chemical analysis,
has extracted an elementary sensation from the complex
group in which it was included, has joined it to an abso-
lutely similar elementary sensation, and formed a new
compound, the sensation of musical sound.*
* Mueller (tr. Baly), ii. 973 and 1298. The wheel of Savart shows us that a
second elementary sensation is necessary and sufficient to effect this extraction and
form the new compound.
CHAP. I.] SEXSATIONS OF HEARING, & THEIR ELEMENTS. 109
But if, among musical sounds, we choose a very deep one,
for instance, the lower octave of the organ, we see that the
elementary sensations, though still forming a continuous
whole which they must do for the sound to be musical
nevertheless remain to a certain extent distinct. " The
lower the note, the better does the ear distinguish in it
the successive pulsations of the air."* It is then not
much removed from a buzzing, that is to say, a simple
noise. We distinguish in it elementary sensations ; we re-
cognise that each of them consists in a swelling and a dying
away, that is to say, in an increase and a diminution of in-
tensity ; we can observe the limits of each one of them ;
these limits are but half effaced. We find, on comparing it
with the elementary sensation corresponding to a more acute
note, that it occupies a greater length of time. Again, the
length of time is greater between the maximum of height
of one of its elementary sensations, and the maximum of
height of the succeeding one. The whole sensation is- thus
composed of larger molecules and more distant maxima.
This is why we call it a fuller or heavier sound. Here we
perceive the elementary sensation whose different combina-
tions are sufficient to explain all the sensations of sound.
Let us first consider musical sounds. We know by
acoustics that the condition of a sound being musical is
that there be a uniform series of vibrations of the air ; that
each of these vibrations is of certain length, and lasts a
certain fraction of a second ; that the more it diminishes in
length and duration, the more acute becomes the note. All
analogies show that there are elementary sensations in this
case, just as in that of the very deep note, and scientific
experiment comes in to confirm these inductions. Take a
wheel with two thousand teeth revolving n a second; it
gives two thousand blows in a second, and therefore two
blows in the thousandth part of a second ; if all the teeth
except two adjoining ones are now removed, the two blows
* Helrnholtz, " Conferences Scientifiques de Bonn." " Revue des Cours Scienti-
fiques," 10th February, 1867, p. 78.
110
OF SENS A TIONS. [BOOK III.
which it will give when set going again will only occupy
the thousandth part of a second.* Now these two blows
cause a determinate and appreciable sound. The sound,
then, given in a second by the wheel when it has all its
teeth, comprises a thousand similar successive sounds, each
perceptible to consciousness. In other words, the whole
sensation which lasts a second, is made up of a continuous
series of a thousand similar sensations, each lasting one-
thousandth part of a second, and each perceptible to con-
sciousness. But as we have just seen, each one of them com-
prises in itself at least two successive elementary sensations,
which, if isolated, would not come within our consciousness,
and, to be perceptible, must be combined in pairs. Here we
have the elements of a sensation lasting a second, and the
elements of its elements.
Now, in the passage from the deep to the acute note,
what become of these elementary sensations of which we are
conscious? It is plain that each of them lasts less and
less time and that its maximum sound becomes nearer and
nearer to the maximum of the succeeding sound ; hence it will
necessarily become less and less distinct, and at last we shall
cease to perceive any maximum or minimum in it; this is what
happens ; in proportion as the note becomes acute, the num-
ber and plurality still apparent, though indistinctly, in the
low note, disappear and wholly vanish. Consciousness no
longer distinguishes, even vaguely, the little composing
sensations ; the whole sound appears one and united. At
the same time, it puts on a new appearance, it seems
thinner and more drawn out. This arises from the closer
arrangement of the maxima, and from the shorter time
occupied by the molecules of the sensation, which, though
as numerous as before, are smaller. It follows that, as
regards consciousness, our sensations of sound arrange
themselves in a pyramid : at the base, are those of very deep
sound, composed of longer elementary sensations and more
distant maxima j at the summit, are those of very acute
* Mueller (tr. Baly), ii. 973 and 1298, Experiments of Savart.
CHAP. I.] SENSATIONS OF HEARING, & THEIR ELEMENTS. Ill
sound, composed of shorter elementary sensations and of
more closely ranged maxima ; this is why we say of sounds
that some are higher and some lower, and arrange them in
a scale. Hence we see that the qualities of deep or acute,
of high or low, of full or drawn out, of vibrating or firm,
by which we distinguish the different notes of the scale,
depend on the degree of brevity of the elementary sensa-
tion, and the degree of proximity of its maxima. Here, i
already, we have reduced quality to quantity.
IV. It is also thus reducible in other respects. First,
as to intensity, the reduction is complete. The different
degrees of force or intensity of any one sensation of sound
are the different degrees by which it passes from its mini-
mum to its maximum, and we know that these degrees
have as their necessary and sufficient condition different
degrees of condensation of the wave of air. Now, mathe-
matics show us that in each elementary wave, there is a
maximum and a minimum of condensation, which explains
how it is we find in each elementary sensation a maximum
and a minimum of intensity. Mathematics further show
that in the two series of waves produced by two notes
sounded in unison, the condensations combine and become of
double strength ; which explains how it is that in the sen-
sations of sound so produced the intensities combine and
become doubly as great. Consequently, when we are given the
law connecting the elementary sensation with its condition,
we are able to follow the elementary sensation under all its
aspects and in all its degrees, far above the range of con-
sciousness, by following mathematically the changes and
degrees of its condition.
In the second place, an indirect analysis comes to our
aid to explain with the most complete success that unde-
finable quality which seemed to resist all the efforts of
direct analysis, tone.* If the same note is played by
various instruments of different tone, it is not a simple
sound but a combination of sounds, of which the principal
Helmholtz, " Die Lehre von den Tonempfindungen. "
112 OF SEX 8 A TIONS. [BOOK III.
olie the same for all the instruments is the fundamental
note ; and the others, varying with particular instruments,
are supplementary notes of less strength, termed superior
harmonics, arising from vibrations twice, three, four, five, six,
seven, eight, nine, or ten times as quick as those of the
fundamental note. Thus, in the piano, we can hear without
difficulty the six first harmonics of each note, but not the
seventh or ninth. The violin, under the bow, gives the
six first harmonics more feebly; but the higher ones, from
the sixth to the tenth, are very distinct. The pipes of
covered organs give a hollow sound, arising from the isola-
tion of the odd harmonics. The clarionet gives a nasal
sound, in which again there are only the odd harmonics ;
but of these, the higher ones predominate. Hence it
follows that differences of tone arise from the addition of
different harmonics to the fundamental note. By following
out this principle, and with the aid of an instrument called
a resonnateur, it has been proved that this same circum-
stance explains the different vowel-sounds of the human
voice that is to say, the variations which the same note
presents, when pronounced in turn u, a, e, i, o, eu, ou.
Analogous considerations show us how sounds become either
harsh and rough, or smooth and even. So that these dif-
ferences of sensation hitherto irreducible, and denoted by
idle metaphors, are reduced to the intervention of little sub-
sidiary and complementary sensations of the same kind,
which, attaching themselves to the principal sensation, give
it a special character and unique appearance, while con-
sciousness, which sees the whole and nothing but the whole,
is unable to distinguish these feeble auxiliaries, and there-
fore to recognise that, though inferior in strength to the
principal sensation, they are, in nature, identical with it,
and that, while entirely similar to one another, they differ
only, according to the tone, in number and acuteness.
This being settled, we are in a position to explain sensa-
tions of noise, and their innumerable varieties. The science
of acoustics shows us their general mode of formation,
though without entering into the details of each particular
CHAP. I.] SENSATIONS OF HEARING, & THEIR ELEMENTS. 113
one. Like sensations of musical sounds, they are com-
pound. But while the sensation of musical sound corre-
sponds to a series of vibrations, equal in length and duration,
that of noise corresponds to a series of vibrations, unequal
in duration and length ; and hence we conclude that in
the first instance the elementary sensations are similar, and
in the second dissimilar ; and this explains the infinite num-
ber of sensations of noise and the impossibility of grouping
them like those of musical sound in a single series ; there are
no limits to the combinations of dissimilar sounds ; having
no fixed relations between themselves, they can only produce
a chaos.
We see now in what all the differences and peculiarities
of sounds consist. Given two continuous elementary
sensations, the one preceding and the other following,
the two united form, as far as consciousness is concerned,
a single whole sensation, which we term a sensation of
sound. If the two are similar, the sound is musical ; if
they are dissimilar, it is a noise. If, in the couple so
formed, the elements are of longer duration, the sound is
deeper; if of shorter duration, the sound is more acute.
In every elementary sensation, there is a maximum ; and
according as the time between two maxima diminishes, the
sound becomes more even. If the maxima of one couple
are greater than those of another, the whole sound of the
first couple is more intense than the whole sound of the
second. If to the whole sound be added complementary
sounds, less intense, and twice, three, four, or several
times as acute, the tone varies with the variations of the
complementaries. If we conceive two given elements, on
the one hand, the elementary sensation, on the other, the
quantity we call time ; we have in them the materials neces-
sary to construct sensations of sound. Two elementary
sensations are discontinuous or continuous, that is to say,
are separated by an appreciable or un appreciable portion of
this quantity; and the sound is accordingly null or appreci-
able. They occupy equal or unequal portions of this quan-
tity; and the sound is accordingly musical or not musical.
114
OF SENSATIONS.
[BOOK. III.
The portions so occupied are larger or smaller ; and the
sound accordingly becomes deeper or higher. If we now
conceive the magnitude or intensity of the elementary sensa-
tion itself; with this new element, the construction is accom-
plished. The elementary sensation having a maximum of
intensity, the maxima of two elementary sensations may
he discontinuous or continuous, that is to say, separated
by an appreciable portion of time or not; and the
sensation is accordingly composed of appreciable portions,
or uniform. The maxima of two elementary sensations are
greater or less than the maxima of two others ; and the
sound is accordingly more or less intense. There are added
to a sound different groups of sounds of less intensity, but
of an acuteness the multiple of its own ; and the sound has
such-and-such a tone accordingly. So that all differences
of sound, though apparently irreducible, are reduced to
differences of magnitude introduced into the same elemen-
tary sensation, these differences being furnished sometimes
by the magnitude or intensity of the sensation itself, some-
times by that particular magnitude we denominate time.
Let us now consider the elementary sensation itself. In
the noise which precedes the musical note,* it is united
with other elementary sensations of unequal duration, and
forms with them a heterogeneous compound. In the
musical note which is formed by accelerated and ap-
proximating noises, it is united with other elementary sen-
sations, of duration equal to its own, and forms with them
a homogeneous compound. But for it to reach our con-
sciousness there must always be one or other of these com-
binations ; it must be enlarged in order to be distinguished.
When isolated, the inner sense does not perceive it ; but
it still exists, for in the very deep musical note we perceive
it incessantly repeated and making up the note; and
again, there can clearly be no compound without com-
ponents. On the other hand, we have seen that in the
high as in the low note, the elementary sensation has a
* See the Wheel of Savart, and the Sirens.
CHAP. L] SENSATIONS OF HEARING, & THEIR ELEMENTS. 115
maximum; we discover this maximum in the very low
note, we do not discover it in the high note ; still it exists
in the one as in the other ; but, in the very low note, the
greater interval between the two maxima enables us to
distinguish them, while, in the high note, their proximity
prevents our doing so. Further than this, every elemen-
tary sensation, in order to pass from its minimum to its
maximum, passes in its short duration through an infinite
number of degrees ; much more therefore are these degrees
insensible to consciousness; so that, in a high note, the
indistinct elementary sensation comprehends not only two
indistinct extreme states, but an infinite number of indis-
tinct intermediate states.
We get a glance here at the obscure and infinite world |
extending beneath our distinct sensations. These are com-
pounds and wholes. For their elements to be perceptible
to consciousness, it is necessary for them to be added
together, and so to acquire a certain bulk, and to occupy a
certain time ; if their group does not attain this bulk and
does not last this time, we observe no change in our state.
Nevertheless, though it escapes us, there is one ; our in-
ternal sight has limits ; outside these limits, internal events,
though real, are for us as though they did not exist. They
gain accessions, they undergo diminutions, they combine, they
are decomposed, without our being conscious of it.* They
may even, as we have just seen in the case of sensations
of sound, have different degrees of composition, and con-
sequently different degrees of recoil, beyond the grasp of
consciousness. The elementary sensations directly making
* Leibnitz, " Des Perceptions Insensibles," p. 65, " Nouveaux Essais sur
1'Entendement," Ed. Jacques.
" To hear the sound of the sea, from the shore, we must necessarily hear
the parts which make up the whole, that is to say, the noise of each wave,
though each of these little noises only makes its-elf known to us in the confused
assemblage of the whole, and would not be observed if the wave causing it were
alone by itself. For we must be affected a little by the movement of this wave,
and must have some perception of its sound, however slight; otherwise we
should have none of the sound of a hundred thousand such, since a hun-
dred thousand nothings cannot make up anything." Cf. Hamilton, Lectures,
&c., i. 349-351, cited Mervoyer, " De 1'Association des Idees," p. 337.
i 2
116
OF SENSATIONS.
[BOOK III.
up our ordinary sensations are themselves compounded
of sensations of less intensity and duration, and so on.
Thus, there is going on within us a subterranean pro-
cess of infinite extent, its products alone are known to
us, and are only known to us in the mass. As to elements
and their elements, consciousness does not attain to
them, reasoning concludes that they exist ; they are to sen-
sations what secondary molecules and primitive atoms are
to bodies ; we have but an abstract conception of them,
and what represents them to us is not an image, but a
notation.
CHAP. II. SENSATIONS OF SIGHT, ETC. 117
CHAPTER II.
SENSATIONS OF SIGHT, OF SMELL, OF TASTE, OF TOUCH, AND
THEIR ELEMENTS.
I. A SIMILAR, though somewhat less complete, reduction
may be effected with sensations of sight.* We all know
that a ray of white light may be divided with a prism into
several rays of different colours. It spreads out into a
spectrum, in which the colours form a continuous scale.
At the commencement of the scale is red; then come
orange and the different yellows, then green, the different
blues, indigo, and lastly violet,f and each of these tints
passes by intermediate stages into the one preceding it and
the one following it. Here are an infinite number of dis-
tinct sensations connected by intermediate stages. Let us
examine their external conditions. The science of optics
shows us that the spectrum is formed by the different rays
which make up the white ray being inflected, some more
and some less, in passing through the prism ; this inflection
increases with the shortness and rapidity of the waves;
therefore, if we follow, from red to violet, the series of rays
which form the spectrum, we find that the shortening and
acceleration of the waves go on increasing. Thus, from
red to violet, each sensation corresponds to waves quicker
and shorter than those of the preceding sensation, slower
and longer than those of the succeeding sensation. An in-
crease of speed and diminution of length in the waves are
sufficient to determine the variations which our sensation of
colour undergoes in passing from red to violet.
* Helmholtz, " Physiologische Optik," part ii.
t M. Helmholtz distinguishes the following successive colours : red, orange,
golden yellow, pure yellow, greenish-yellow, pure green, bluish-green, blue of
water, cyanic blue, indigo, violet and ultra-violet.
118 OF SENSATIONS. [BOOK III.
Having premised this, let us consider the red; as we
go down the spectrum,, the sensation of red diminishes ; it
passes from its maximum to its minimum. There is then an
elementary sensation, which decreases in proportion as the
waves become shorter and more rapid. But there is more
than one such ; for if there were only one, we should find that
as we passed towards violet, it would simply grow feebler with
the shortening and acceleration of the waves, and the entire
spectrum would only present degrees of intensity of red, while
in fact, we find at what appears to be the minimum of red,
a second distinct sensation arising, that of yellow. There
are then, at least two elementary sensations of colour.
Are there but two ? If there were only two, for instance,
that of red and that of yellow, the red, having its maximum
at the commencement of the spectrum, and the yellow
having its maximum at the centre of yellow, the first de-
creasing with the time and length of the waves, the second
decreasing whenever the time and length of the waves are
less or greater than the degree of time and length corre-
sponding to the centre of yellow, we should see, on passing
down the spectrum below this centre, yellow become inde-
finitely feebler till the end of the spectrum, without under-
going any other change. This is not so ; for at the lower
minimum of yellow we find a new distinct sensation appear,
that of green. There are then, at least three elementary
sensations, and on studying the composition of the spec-
trum we find it is sufficient to admit three, one analogous to
that of red, another to that of violet, and the last to that
of green.
All the three are excited by every ray of the spec-
trum ; but each of the three is differently excited by the
same ray. The first is at its maximum at about the central
point of red; in proportion as we descend towards the
violet and the waves become shorter and more rapid, its
intensity diminishes and approaches its minimum. The
second is at its maximum at about the centre of the violet ;
and as we go back towards the red, and its waves become
longer and slower, its intensity diminishes and approaches
CHAP. II.] SENSATIONS OF SIGHT, ETC. 119
its minimum. The third is at its maximum at about the
central point of the green ; in proportion as we return to-
wards the red, or descend towards the violet, that is to say,
as the waves become either longer and slower, or shorter
and more rapid, its intensity diminishes and approaches
a minimum. So that, as we pass from red to violet through
all the degrees of the spectrum, the three component sensa-
tions vary from degree to degree, but each one in a special
manner, the first passing insensibly from maximum to
minimum, the second from minimum to maximum, the
third passing first from a minimum to its maximum, and
then from its maximum to a minimum, which explains at
the same time the insensible passage by which every compound
sensation in the spectrum is connected with the succeeding
one, and the diversities of the ten or twelve principal com-
pound sensations.*
We can readily see the object of this disposition of our
being. If a simple ray excited in us one sensation of
colour only, it would have a maximum, a minimum, and
intermediate stages, nothing more ; and for want of being
able to contrast it with another, we should not observe it ;f
we should have no notion of colour ; the luminous waves,
in increasing or decreasing in speed and length, would only
render the sensation more intense or more feeble ; objects
would differ only in higher or fainter colour ; they would
resemble the various parts of a drawing in which all the
* Helmholtz, ib. 191. The substance of this explanation is due to Young. He
supposes that every nervous fibre of the retina is made up of three elementary
fibres, differently excitable by the same ray. As Helmholtz observes, we may
suppose that every nervous fibre of the retina possesses three different kinds of
activity, excitable by the same ray, and this is very probable, But we may dis-
pense with all suppositions by admitting, instead of three nervous fibres or three
nervous activities, three elementary sensations. In the anatomical or physiological
hypothesis, the assumed fact is uncertain ; for it is not certain that there are three
different fibres in every nerve, or that one fibre has three kinds of action. In the
psychological explanation, the admitted fact is positive ; for it is certain that the
three sensations, red, green, and violet, exist. I have therefore made the neces-
sary changes in the explanation of Helmholtz. " This hypothesis of Young's," he
says, " gives a complete view and extraordinarily clear and simple explanation
of all the phenomena connected with the physiological science of colours."
f " Persons affected with achromatopsy can only distinguish degrees of light and
dark, they see all objects as they are represented in photography." Wecker*
' Maladies des Yeux," ii. 432.
120
OF SENSATIONS.
[BOOK III.
differences are those of white, grey, and black. If, on the
other hand, every simple ray excited two sensations of colour
only, we should still have the notion of colour ; we should
still distinguish two principal colours, their maxima, minima,
intermediates and compounds ; but very many of our sensa-
tions of colour would be wanting, and their whole arrange-
ment would be reversed. This we observe in studying
various cases of illness or congenital infirmity, and the theory
reducing our elementary sensations of colour to the three
sensations of red, violet, and green, receives here a most
striking confirmation from experience.* The sensation of
red is wanting in some persons ; in others, that of green ;
after taking santonine, the sensation of violet is lost for some
hours. In all these cases, not only is a principal sensation
missing, but many others are altered, and both losses and
alterations are precisely those which, according to theory,
would result from the absence of the elementary sen-
sation. Finally, we obtain a more delicate and definitive
verification.f According to the theory, the red and violet
of the spectrum are, even at the points at which they seem
most intense, compound sensations ; for, to the elementary
sensation which is then at its maximum, are joined two
others which are then at a minimum ; the first then is
mingled and weakened ; it is neither absolutely pure nor of
the greatest possible strength. It will, then, be purer and
stronger if we can remove these causes of impurity and
weakness. Now there is a case in which we are able to do
this ; that is, when we have blunted the sensibility of the
eye to the other colours. In this case we ought to see a
red or violet more intense than those of the spectrum ; and
this is what happens. In this instance, which is unique, we
* Helmholtz, 294, 848, 293, and Wecker, ibid. "The ingestion of santonine
>nngs on a particular variety of Daltonism by making the retina insensible to
violet rays. . . ." Some persons " have no perception of blue ; this state always
omcides with insensibility of the retina to red rays. Others while distinguishing
nite, grey, and black from all other colours, do not distinguish other colours from
e another. In others, the retina is insensible to violet, while other colours
are perceived, if strongly marked and in a bright light."
t Helmholtz, ib. 369, 370.
CHAP. II.] SENSATIONS OF SIGHT, ETC. 121
are able to isolate one of our elementary sensations of
colour. By a lucky hit in psychological chemistry, we
extract it from the ternary compound in which it is usually
combined, and in which theory alone had detected it.
II. With the three elementary sensations of colour we
are able to construct the rest. And first, if we represent
by a curve the increase and decrease which each of them
undergoes as it passes down the spectrum, we shall see the
three different variations of their respective intensities pro-
duce the different colours of the spectrum.* The longest and
slowest waves, placed at the summit of the spectrum, excite
the elementary sensation of red strongly, and the two others
feebly; the result is the sensation of spectral red. Lower
down, at the point denoted by yellow, the waves, already not
so long and slow, excite the elementary sensations of red and
green with moderate intensity ; and that of violet feebly ;
and then we have the sensation of spectral yellow. Towards
the middle of the spectrum, the waves, which then have a
medium length and speed, excite the elementary sensation
of green strongly, and the others much more feebly ; our
entire sensation is that of spectral green. Lower down,
when the waves begin to grow short and quick, the ele-
mentary sensations of violet and green are excited with
moderate force, and that of red more feebly ; then we see
spectral blue. Towards the lowest part, when the accelera-
tion and shortening of the waves has further increased, the
elementary sensation of violet is strong, and those of red
and green are very weak ; and the compound sensation we
call violet is produced.
On the other hand, when the three elementary sensations
are of about equal force and no one predominates over the
others, we have the sensation of white, or of whitish colours.
This happens in many cases ; first, when all the rays of the
spectrum, collected again by another prism, strike the
retina at the same point, and thus produce the maximum,
minimum, and all the degrees of each elementary sensa-
Helwholtz, 291.
122 OF SENSATIONS. [BOOK III.
tion ; again when, two rays being selected from the spec-
trum, the inequality of the three elementary sensations
excited by the first is compensated by the inverse inequality
of the three elementary sensations excited by the second.
In this case, the two spectral colours produced by the two
rays are said to be complementary to one another, and they
form a distinct couple. Among such couples we reckon four
principal ones, red and bluish-green, orange and cyanic blue,
yellow and indigo, greenish-yellow and violet ; combined in
their respective pairs, these colours give us the sensation of
white, and we find a fixed distance between such pairs on
the spectrum. If, on the contrary, we take the two colours
at the furthest distance from one another on the spectrum,
red and violet, their mixture produces a sensation of dis-
tinct colour, that of purple. These two observations afford
us the law governing all mixtures of spectral colours.
Two colours being given for mixture, their distance on the
spectrum, compared with the fixed distance between comple-
mentary colours, differs from it by a greater or less quan-
tity. The smaller this quantity is, the nearer to white or
whitish will be the colour produced by the mixture ; and
on the contrary, the greater this quantity is, the freer from
white, or more " saturated," will the colour formed by the
mixture be. On the other hand, this distance may exceed
or be less than the fixed distance. The more it exceeds
the fixed distance and the nearer it approaches to the ex-
treme possible distance, the nearer will the colour formed
by the mixture approximate to purple, which is produced
when the separation is most complete ; on the contrary, the
further it is below the fixed distance and the smaller^ the
separation becomes, the more does the colour produced
approximate to the intermediate colour, in which the sepa-
ration of the two component spectral colours disappears.*
All these conclusions are confirmed by experience.
A last colour remains, black, which is not a sensation,
but the absence of all sensation at a particular place and
* Helmholtz, 279.
CHAP. II.] SENSATIONS OF SIGHT, ETC. 123
moment, when this place and moment are compared with
others in which the sensation is present. But conscious-
ness is so ill-acquainted with our internal events that she
places in the same rank, as colours, our sensations and our
wants of sensation ; what strike her are differences be-
tween our states, and, on account of this, she sets together
as similar facts the passage from repose to action, and that
from action to repose, observing them as contrary, but with-
out distinguishing that one is negative, the other positive.
The different degrees of black or of want of sensation
come in then to complicate the colours already constructed.
" Prismatic analysis proves that grey becomes identical
with white, brown with yellow, reddish brown with red,
olive green with green, when the white, yellow, red, and
green are feebly luminous."
These data being given, we have all the elements neces-
sary to explain all sensations of colour, and we see the j
elements of the sensation form compounds, which combining
together form more complex compounds, and so on, just
as we see physical atoms form chemical molecules, these
form chemical compounds, and these again, the ordinary f
minerals found in nature. By our utmost analysis we
arrive at three elementary colours, all simultaneously ex-
cited, though each one differently, by a simple ray of the
prism. Their union forms a spectral colour. Many
spectral colours united form, in accordance with a fixed
law, white, purple, and an infinite number of compound
colours ; and the addition of black, that is to say, the en-
feebling the whole sensation, introduces an infinity of shades
in all these products. These products themselves form, by
their combinations, the ordinary colours we observe in the
world surrounding us.
Positive science stops here ; experience does not enable
us to mount higher than the three elementary sensations of
colour. We are dealing with an instrument far more com-
plicated than the sensation of hearing. In fact, for every
undulation we have three sensations instead of one. With
sound again, the vibrations sometimes succeed one another
124
OF SENSATIONS.
[BOOK III.
slowly enough to enable us to distinguish the elementary sen-
sation corresponding to each of them ; there are only sixteen
and a half per second in the ut of an organ-pipe thirty-two
feet long ; and so we are able to observe that our whole sen-
sation is made up of successive small sensations having each
a maximum and minimum ; we distinguish almost precisely
these component sensations. With sight, on the contrary,
at the extremity of red, the part of the spectrum where the
vibrations succeed most slowly,* there are 451 billions of
them in a second ; it is plain that, were we able to isolate the
sensation of red from the two other elementary sensations,
we could never distinguish from one another component sen-
sations so prodigiously numerous and of so prodigiously short
duration. All we can admit with confidence is that the
elementary sensation of red, like that of the lowest note of
ut, is composed of successive sensations. For Wheatstone's
experiments show that such a light as that of the electric
spark is enough to produce a sensation on the retina; that
this light is, so to speak, instantaneous; that it lasts less
than the millionth of a second; and that thus a sensa-
tion of light lasting a second is made up of at least a
million successive sensations. The number of these cannot
be determined ; it is probably much greater ; perhaps
with the ethereal undulation, as with the undulation of air,
two successive vibrations are sufficient to produce a sen-
sation still perceptible to consciousness ; if so, the shortest
sensation of light perceptible to consciousness would as is
the case with the shortest sensation of hearing perceptible
to consciousness be compounded of two elementary sensa-
tions imperceptible to consciousness, and having each a
maximum or minimum and intermediate stages. Without
pushing the induction to this extent, the case of the electric
spark shows that the sensation of light, like that of a very
acute sound, is composed of a continuous succession of very
numerous, successive, and similar sensations, forming, as far
* Mueller (tr. Baly), ii. 1109, and Helmholtz, p. 32. 451 billions for the
slowest, 789 billions in the quickest.
CHAP. II.] SENSATIONS OF SIGHT, ETC. 125
as we are concerned,, a simple undecomposable mass. A new
proof of the unnoticed work going on in the depth of our
being, beyond the range of onr consciousness, and a new ex-
ample of the latent, complex, and innumerable combinations,
of which we only perceive the totals or the effects.
III. We must not expect to find such complete redac-
tions in the cases of taste and smell. With air, or ether,
we know the mode of action, which is, an undulation of
calculable length and speed, and thus we are able to draw
conclusions from it to the corresponding sensations. Be-
sides, this mode of action is uniform, and the nerve, more-
over, is specially constructed to receive it ; we find proof of
this in the designed structure of the organism of which the
nerve forms part, and in the similitude of the sensations
produced through the nerve by a blow or an electric current
applied to the eye or ear. The nerve itself, then, is capa-
ble of uniform action ; and so it is natural that sensations
excited by its action should be readily referable to a simple
type, as happens with those of sound, or to types few
in number, as with those of colour. With the other
groups of sensations all this is reversed. We are igno-
rant of the mode of action of volatile substances on the
olfactory nerves and of liquified substances on the gustatory
nerves ; it is recognised to be chemical, but here our
knowledge stops ; we do not know whether it is an un-
dulation or what other movement ; we have not the least
idea of its elements, and are unable to avail ourselves of
such an idea to form conclusions as to the corresponding
sensations. And yet, from the single fact that it is
chemical, we may conclude something as to the composition
of the sensations it excites in us through the medium of
the nerve.
Before commencing this inquiry, we must distinguish sen-
sations of smell and taste, strictly so called, from accompany-
ing sensations. For, what we term a smell or taste is, in
general, a very complex sensation; the olfactory or gusta-
tory nerves only contribute a part of it ; another very con-
siderable part is referable to nerves of touch, similar to
126 OF SENSATIONS. [BOOK III.
those spread over the rest of the body, and from which we
receive sensations of contact, of muscular contraction, heat,
cold, local pains, and all their kinds. To begin with smell.*
Numbers of what are termed sensations of smell comprise
other sensations. And first, sensations of pungent smell are
divisible in two parts ; they all comprise sensations of touch
and, perhaps, are nothing more ; such is the smell of am-
monia, which is principally a stinging, as it is transmitted by
other nerves than the special ones ; the vapour of ammonia
produces on the conjunctiva an effect precisely similar to its
smell. This stinging may subsist even after the strict sensa-
tion of smell has been lost ; some great snuff-takers become
insensible to smells, pleasant or otherwise, but continue to
take snuff, as they still feel the tingling it produces. Appe-
tizing and nauseating smells are also thus divisible. The
strict sensation of smell is here combined with another, which,
according to the state of the stomach, ceases, is augmented, or
reversed ; the same smell, that of a plate of hot meat, is agree-
able when we are hungry, and disagreeable when we are
suffering from indigestion ; it is probable that, in this case,
certain deep-seated nerves of the alimentary canal are called
into action, and that the whole sensation is made up of a
sensation of the olfactory nerves and several accompanying
sensations. Finally, we may also divide refreshing and suffo-
cating smells, comprising, on the one hand, those of the
volatile salts, of eau-de-Cologne, of tar, of tan ; and, on the
other hand, that of a close room, of a pastrycook's shop, of a
cotton factory, of a cloth warehouse ; here we plainly have,
in addition to the strict sensation of smell, a sensation of
comfort or uneasiness, arising from the air-passages, and con-
ducted by the nerves of touch and pain. I think, too, that
in many cases, if, for instance, we inhale alcohol, a feeble
sensation of heat comes in to complicate the strict sensation
of smell. Pure sensations of smell remain, agreeable or
disagreeable in themselves ; those, for instance, of the violet
and of assafoetida ; there are an infinite number of them,
* Bain, " Senses and Intellect," 173.
CHAP. II.] SENSATIONS OF SIGHT, ETC. 127
of which we can only say, that they are agreeable or dis-
agreeable ; in themselves, they resist all analysis,, and in
order to denote them we have to name the bodies producing
them.
As to taste, what we generally term a flavour, comprises,
besides the strict sensation of taste, a number of sensations
of other kinds. In the first place, as the back of the mouth
and nose communicate, the olfactory nerve is in operation
at the same time as the gustatory.* " If you close your
eyes and nostrils, and have different kinds of sweetmeats,
for instance, placed on your tongue, then aromatic creams,
of vanille, of coffee, &c., in every case you will only perceive
a sweet, sugared taste, and will not be able to distinguish the
different substances employed/'' In the same way it can be
proved that " the urinous taste we attribute to fixed alkaline
bases, does not belong to these substances, but to the am-
monia set free by the reaction of the fixed alkaline bases on
the ammoniacal salts contained in the saliva." Here, again,
a sensation of smell, or rather of nasal touch, is included in
the sensation of taste. Secondly, strict sensations of taste
are frequently combined with a different sensation, some-
times agreeable and attractive, sometimes disagreeable and
repulsive, belonging to other nerves of the alimentary canal.
This accompanying sensation varies, while the others remain
constant; the same good plate of meat is agreeable or dis-
agreeable, accordingly as the stomach is empty or loaded.
Besides this, it arises in other ways ; it has no need, like the
other, of chemical action as an excitant ; mere contact is
enough ; a finger or a feather in the throat will produce a
sensation of disgust. Thirdly,f "Many impressions referred
to taste are simply tactile " such, for instance, are acrid, irri-
tant, astringent flavours, which are sensations of touch, not of
taste. Fourthly, certain flavours are combined with sensa-
tions of heat and cold ; the sensation of heat accompanying
strong drinks is well known, and also the cool sensation we
* Longet, " Traite de Physiologie," ii. 171. Bain, " Senses and Intellect," 157.
t Vernier, cited by Longet, "Traite d' Anatomic et de Physiologie du Systeme
Nerveux," ii. 170. Bain, ibid.
128 OF SENSATIONS. [Boon III.
find as an element in the flavour of certain sweetmeats.
Lastly, different sensations are excited by the same body
in different parts of the mouth, and not only different
accompanying sensations, but different sensations of pure
taste.* " Numbers of bodies, and particularly the salts,
exhibit the remarkable peculiarity of exciting, when applied
to the back of the tongue, an entirely different sensation
from what they excite when applied to the anterior part.
Thus, the solid acetate of potash, of a burning acidity in the
anterior part of the mouth, becomes insipid, bitter, and nau-
seating at the back, and loses entirely its acid pungent taste.
Hydrochlorate of potash, simply salt and fresh in the an-
terior part, becomes sweetish at the back. Nitrate of
potash, fresh and pungent in front, is insipid and slightly
bitter at the back. Alum is fresh, acid, and astringent
when crushed in the front of the mouth, while behind it gives
a sweetish taste without the least acidity. Sulphate of
soda is distinctly salt in front, and distinctly bitter behind."
Acetate of lead, fresh, piquant, and astringent in front, be-
comes sweet at the back. Hence it follows that an ordi-
nary sensation of taste may have several distinct elements in
itself, in addition to the four kinds of elements furnished
by accompanying sensations. For, in addition to the non-
gustatory nerves, there are different gustatory nerves which
intervene to produce it. The mouth, then, is not a simple
organ, but a succession of organs, and a taste, even one
strictly so called, may be a succession of tastes.
Let us simplify the matter ; let us lay aside all that
part of the sensation which may be referred to touch, such
as acidity, astringency, irritation, heat, coolness, the spon-
taneous muscular sensation radiating towards the alimentary
canal, and consider simply the sensations of the gustatory
nerves themselves, and put them on the same footing,
whether they arise in the anterior part, or at the back of
the mouth ; their principal types are the sensations of
* Longet, "Traite de Physiologie," ii. 167. "Experiments of Guyot and
Admyrauit."
CHAP. II.] 8SN8ATIO&8 OF SIGHT, ETC. 125
bitter and sweet, with tlieir innumerable varieties ; when
we have thus named them, we are at the end of our know-
ledge, as happened just now when we called sensations of
smell fetid or perfumed. Still, let us see what we can
learn in either case by availing ourselves of previous reduc-
tions, and by studying the circumstances in which these sen-
sations arise. They have, like the rest, as direct stimulus,
an action of the nerve transmitted to the nervous centres.
Now it is admitted, in accordance with all known facts, that
two different sensations indicate two different states of the
nervous centres, and, if the same nerve is concerned, two
different actions of that nerve. It remains, then, to be
known in what way the olfactory or gustatory nerves act ;
and, to arrive at this, we must determine the external event
in immediate sequence to which its action commences.
Nothing is easier than to know the antecedents of this
event ; but it is difficult to determine accurately the event
itself. We see, at first sight and by ordinary experience,
that such a body excites in us such a sensation of taste or
smell, that another excites in us the sensation of red or
blue ; but neither one nor the other excite these sensations
otherwise than through media ; the science of optics was
required to tell us that undulations of an ether of certain
length and speed are the media of action of the second ; and
it would be necessary to have recourse to a science already con-
structed to determine the media of action of the first. Let
us inquire, however, into this last immediate event in direct
sequence to which the olfactory or gustatory nerves begin
to act. A body has no taste unless in solution ; the taste is
increased when it is moved about and pressed to the gusta-
tory membrane;* this membrane, again, must not be dry,
or rendered insensible by cold. Again, the gustatory nerves
are probably protected by a colloid membrane, perme-
able, as are all such, to non-colloid substances, but nearly
impermeable to -colloid substances, which accounts for the
taste of non-colloid substances, and the want of taste in
* Bain, "Senses and Intellect," 156, 168.
K
130 OF SENSATIONS. [Boo* III.
colloid ones. All these facts lead us to the conclusion
that the dissolved molecules of the body which is tasted
penetrate the tissues of the tongue, and come in contact
with the nervous papillae ; and there, under the influence of
the animal heat, form with the liquid secretions a chemical
combination varying with the variations of these secre-
tions.* Similarly, a body has no smell, except in a gaseous
state ; and the pituitary membrane must not be dry ; it is
also proved that, to be odorous, a gas must combine with
oxygen at the surface of the pituitary membrane. All
these facts lead to one and the same conclusion, that the
molecules of gas become absorbed in the moisture of the
pituitary membrane in contact with the olfactory fibres,
and there form a chemical combination with the oxygen of
the air. Thus the action of the olfactory nerve, like that
of the gustatory nerves, appears to have a chemical com-
bination as its immediate antecedent.
Now what is a chemical combination ? Chemists reply
that a homogeneous body is made up of molecules precisely
similar to one another, and extraordinarily small ; that
each of them, if the body is not simple, is itself composed
of several different atoms much smaller still, and so situated,
with respect to each other, as to remain in equilibrium ; that
a chemical combination takes place when a molecule, re-
ceiving an atom of another kind, passes into another state
of equilibrium ; that the atoms then leave their respective
positions to take up new ones ; that these displacements of
atoms, acting ^at extremely small distances, are themselves
extremely small ; that, as these atoms are wonderfully small,
we must, to explain their active force, attribute to them, on
displacement, velocities of enormous magnitude ; and that,
therefore, every distinct chemical combination is made up
of a distinct system of prodigiously small and rapid displace-
* Longet, ii. 164." The most delicate kinds of food are tasteless, earthy or
bitter when the stomach is out of order. . . . The brain and sensorial nerves
remain as they were, but the tongue is covered with a mucous or bilious coating,
and everything produces a dull nauseous impression." Mueller (tr. Baly), ii.
1323. "After chewing the root of the sweet-flag, inilk and coffee taste acid
to me."
CHAP. II.] SENS A TIONS OF SIGHT, ETC. 131
ments, of which we cannot yet indicate the elements or ex-
plain precisely the type.* Here we have the immediate ante-
cedent of the action of each olfactory or gustatory fibre ; and
we cannot help observing how closely it resembles the imme-
diate antecedent of the action of the optic nerve, but with
this difference, that in the second case the type and elements
of the antecedent are known. In fact, in the vibration of
ether, the active particles are also of extraordinary minute-
ness ; their displacements are also wonderfully small and
rapid ; they form, also, a number of distinct systems. Only
we know that these systems are all made up of waves, and we
can measure the speed and length of each wave ; and thus
we are able to define exactly the elementary displacement
by whose repetition each system is formed, to show that,
in different systems, the elementary displacements differ
in respect of quantity only, to reduce them all to a single
type, to denote the corresponding elementary action of the
optic nerve and brain, and to conclude the existence of an
elementary optical sensation, by whose prodigiously rapid
and multiplied repetitions our total sensations of colour are
made up. Unfortunately, chemistry is not so far advanced
as optics ; it can only prove the existence of systems of
displacements, while the other science defines and measures
them ; it must wait till, like its rival, it can represent these
infinitely small events, of which it only knows the final
effect. But it is plain that in the two cases the problem
and solution are of similar nature. In each, movements
are dealt with, the minuteness, speed, and number of
which are wholly disproportioned to the ordinary magni-
tudes we are capable of estimating in time and space. We
may compare, then, the wave of ether to a system of
atomic movements, and a succession of similar waves of
ether to a succession of similar systems of atomic move-
ments. Consequently, thanks to the first case, we can, to
some extent, represent to ourselves the second.
* " Chemistry has as yet been constructed with reference to masses only ; its
construction with reference to velocities remains to be accomplished." Saigey,
"De 1' Unite des Forces Physiques," p. 184.
K2
132
OF SENSA TIONS. [Buos III.
A molecule comes in contact with an olfactory fibre or a
gustatory papilla; a system of atomic movements takes
place in the molecule, and a corresponding action follows
in the fibre ; a second similar molecule arrives at the same
point ; a second similar system of atomic movements takes
place, and a second exactly similar corresponding action
follows in the same fibre. The two similar nervous actions
have aroused two similar cerebral actions and two similar
elementary sensations. But the number of such sensa-
tions, actions, and systems of movements succeeding in a
second is enormous, and the whole sensation of smell or
taste, like the whole sensation of colour, is but the sum of
all the successive elementary sensations, the series of which
occupies a certain time.*
We can now form an idea of the four special senses.
The distinctive character of their sensations is that each,
even the simplest, of those we are conscious of is made up
of a succession of very numerous elementary sensations of
extremely small duration, whose rhythm corresponds to the
special rhythm of an external event, to an undulation of air
or ether, to a system of atomic movements, forming the
external natural antecedent with regard to which the sense
was constructed, and by the presence of which it ordinarily
acts. What constitutes a special nerve is its capacity to
arouse such elementary sensations. Those excited by the
acoustic nerve correspond to undulations of the air comprised
between two limits. Those of the optic nerve correspond to
undulations of ether also comprised between two limits.
Those to which the gustatory and olfactory nerves give rise,
correspond to molecular movements of determinate form.
Compare, for instance, the two sensations which the
same undulations of the air excite through the nerves of
* Certain points of agreement show us the connexion of our sensations of
smell and taste with the atomic constitution, and therefore with the change of
atomic constitution of the molecules (Bain, 152, 165). Three atoms of oxygen with
two atoms of a metal form a compound of sweet or sugary taste. All organic
alkalis are very bitter. Almost all acids have an acid taste. Almost all salts
of iron have an inky taste, &c. Substances with a perfumed smell are carburets
of hydrogen. Substances of fetid smell have, nearly all of them, arsenic or sul-
phur in their bases, &c.
CJIAP. II.] SEXSATIONS OF SIGHT, ETC, 133
touch, and the nerves of hearing ; that is to say, on the one
hand a more or less pronounced quivering and tickling, and
on the other hand a sound more or less intense and acute.
The external antecedent is the same in the two cases ; but
the elementary sensations excited through the medium of
the acoustic nerve correspond to the elements of the undu-
lation of the air, and this is not the case with the elemen-
tary sensations excited by the medium of the nerves of
touch. For, in fact, all details and variations of the undu-
lation of the air are represented in the whole sensation of
hearing, and are not represented in the whole sensation of
touch. In the sensation of hearing, the greater or less
speed of the waves is represented by the greater or less
acuteness of the sound ; the tone, by a supplementary group
of more feeble sensations ; each wave, by an elementary sen-
sation ; the depth of the wave, by the intensity of the sound ;
the degrees of condensation of each wave, by the degrees
of intensity of the sound. With the sensation of touch, on
the contrary, the representation is imperfect ; all we expe-
rience is that the quivering becomes stronger, and degene-
rates into a tickling, when the undulation becomes quicker
and the condensations of the waves become stronger.- And
so again another external event, the undulation of an ether,
represents itself to us in two ways, by the tactile sensation
of heat or cold, and the visual sensation of colour and light.
In the second case, all the degrees of speed and length
which the wave of ether assumes are precisely represented,
but only when their speed and length attain that of the
limit of red, and do not exceed that of the limit of violet.
On the contrary, the first translation represents, not only
waves comprised between the limits of red and violet, but
many other waves situated outside those limits ; but none of
the waves are specially represented, and the sensation of
heat or cold does but roughly represent the difference of in-
tensity separating two systems of successive undulations.
Thus the four special senses are four special languages,
each appropriate to a different subject, each admirably
adapted to express one order of facts, and that order alone.
134 OF SENSATIONS. - [Boos III.
Touch, on the other hand, is a general language applicable
to all subjects, but not well fitted to express the shades of
meaning in the different subjects. In general, a sense is a
system of spontaneous writing and of automatic notation,
resembling the instruments of measurement of which we avail
ourselves in physics and chemistry. Sometimes these are
delicate and special, as the multiplying calorimeter, or the
instrument invented for the self-registration of the movements
of the heart; sometimes they are less delicate and of general
use, as the balance which only serves to denote the final
augmentation or diminution of weight in an experiment.
Sometimes the elementary sensation corresponds, feature for
feature, with the element by whose repetition the external
event is made up; in this case the elementary sensation
copies, one by one, the variations of this element, with their
order and magnitude ; but, if we apply it to elements of
another kind, it is of no effect, or confused, or extreme, and
unfit to represent them. Sometimes the elementary sensa-
tion does not thus correspond, feature for feature, to the
element whose repetition constitutes the external event, and
does not copy the several variations of this element ; but,
in this case, the external event, whatever it be, excites a
body of elementary sensations, the whole of which represent
it as a whole, though unprecisely and in the rough.
IV. This is the character of touch, and we see that it
differs from the other senses, and that its elementary sensa-
tions do not correspond to any elementary external event,
and so cannot be referred to any known type. Here, then,
we are confronted with a new difficulty. There is no special
event here, as in former instances, to serve as a guide in
discovering elementary sensations. We have to seek out a
new path ; before attempting it, let us see whether among
the sensations of touch we cannot find some to which others
may be reduced ; we must clear the ground before attempt-
ing to cultivate it.
In studying cases of partial paralysis, physiologists have
first distinguished two groups of primitive sensations, one
comprising sensations of the muscles, and the other sensa-
CHAP. II.] SENSATIONS OF SIGHT, ETC. 135
tions of the skin, the first having as origin the excitement
of the nervous extremities found in the muscles, the second
having as origin the excitement of the nervous papillse found
in the derma. Each of these two groups may be missing,
without the other being affected.
When the first is wanting, we see that all the sensations
of muscular contraction and expansion are absent, with
all their several degrees of painful effort, fatigue, and cramp,
besides the various sensations of cold, heat, contact, pain,
electric shock, produced by the application of stimuli
to the muscles in their normal state.* " As soon as the
patients take their eyes off their limbs, they have no more
consciousness of their position, or even of their existence.
When, in bed, they lose them, as it were, and are obliged
to look for them, not knowing where they are. Sometimes
they try to stretch out or bend some limb already stretched
out or bent. On moving, they are ignorant of the extent of
their movement, and frequently do not know whether they
have moved or not. If they intend to move, but are pre-
vented, they are unaware of it, and think they have moved,
from having willed to do so. Passive movements may be
occasioned in them by means of an electric apparatus,
without their suspecting it. Their limbs seem to them de-
prived of weight. If their hands are plunged in water,
they know by the cutaneous impression that it is a liquid,
but, on moving the hand about, they do not experience that
soft resistance which gives the notion of the fluidity of
water, and do not know whether their hand is moving in
the air or in the water. If the muscles be pressed, pinched,
or kneaded, no distinct sensation takes place. They do not
perceive the passage of an intense electric shock. A sharp
instrument may be stuck in their flesh without their per-
ceiving it ; that is, unless they discover it through the per-
sisting sensibility of the skin/' Therefore, though they have
retained all their muscular vigour, and are besides insen-
sible to fatigue, they walk with great difficulty in the dark,
* Axenfeld, "Des N^vroses," 339.
136 OF SENSATIONS. [Boo* III.
or when they cease' to watch their movements with
their eyes; the sensations of sight must be constantly
present to supply the place of the absent muscular sensa-
tions. If both sensations fail them, " they can hardly
keep themselves upright without stumbling or running the
risk of a fall ; their movements are either too extensive or
not extensive enough ; they readily let things slip from be-
tween their fingers, or sometimes crush them by too forcible
a contraction." No other sensation is missing; they may
still feel all the cutaneous sensations of tickling, contact,
passive pressure, of superficial heat and pain. In other
words, such patients can no longer estimate the state of
their muscles, but are still perfectly capable of estimating
the state of their skin.
There are patients, on the other hand, unable to estimate
the state of their skin, but who can still estimate the state
of their muscles."* A workman, mentioned by Landry, had
his fingers and hands insensible to all impressions of con-
tact, pain, and heat ; but his muscular sensations were
unaffected. If his eyes were closed, and a somewhat bulky
object were placed in his hand, he was surprised at not
being able to close it ; he had a sensation of resistance, but
nothing more ; he could not say what the object was, what
was its form, size, kind, if it was cold or hot, rough or
smooth, or even if there was any object there at all. A
weight of a kilogramme was tied to his fist with a string
without telling him what it was, and he thought some one
was pulling his arm.
Here, then, we have two groups of sensations and two
groups of nerves as distinct as those of the arm and leg,f
* Landry, " Traite des Paralysies," i. 195, 182, 199.
Brown-SSquard, "Journal de Physiologic," vi. pp. 124615. According
to Brown-S6quard, " sensitive impressions of pain and touch are transmitted in
a cross direction to the spinal marrow, that is to say, the transmission to the
brain of impressions arising in one half the body acts in the lateral half of the
spinal marrow on the opposite side. On the contrary, impressions of muscular
fttton pass without crossing to the anterior part of the spinal marrow."
.sequently " the conductors of muscular sensation differ fundamentally from
the conductors of other sensitive impressions." And the author adds, " not only
conductors not cross in their passage to the spinal marrow, but further,
CHAP. II.] SENSATIONS OF SIGHT, ETC. 137
and, we may add, as similar. For the nerves of the
muscles, like those of the skin, may give rise to sensations
of contact, of cold and heat, of pleasure and pain.* " Per-
sons wounded by a swordthrust, or the cut of a bistoury,
frequently feel, in addition to the pain of the wound, the
chill of the blade and its presence in the depth of the tissues,
and, with many paralytics, although the skin may be quite
insensible to all kinds of stimulation, a pressure, a shock,
the prick of a pin thrust into the soft parts, are felt as
deep-seated impressions of contact, shock, and pain." Be-
sides, these same nerves give us pain when electricity is
passed through them, or when they are excited by a very
strong muscular contraction; and when excited by the expan-
sion consequent on fatigue and shampooing they give plea-
sure. In all these respects, their action is the same as that
of the nerves of the skin, from which they only differ by
terminating in the muscles, and being excited by the
stretching out or shortening of the muscles. But here, there
is no difference of action, the difference is in the ex-
citant; in the strict muscular sensation there is nothing
more than a sort of wrenching, similar to the other sensa-
tions, and capable, like them, of passing into pain if pushed
too far.
Thus we arrive at distinguishing in the nerves of the
muscles, as in those of the skin, three, and only three
kinds of sensations : those of contact, those of heat and
cold, those of pleasure and pain. And further, we find all
they spring from this organ principally if not entirely by the anterior spinal
roots. "
There are very strong proofs of this theory in observations made in cases of
wounds and lateral alterations of the spinal marrow. We see patients lose on
one side, the right for instance, the power of experiencing sensations of touch, of
pain, of cold, of heat, of tickling, and preserve on this same side, not only the
power of moving their limbs, but also that of directing them exactly, and esti-
mating all the degrees of muscular contraction ; the inverse is the case on the
left side. (See particularly the cases cited, pp. 238, 582). In accordance with
this theory, the nerves and conductors of muscular sensations are not only distinct
from the nerves and conductors of tactile sensations, but, more than this, their
anatomical course is different, and we can discover this course in the spinal
marrow.
* Landry, ib. 201.
138 OF SENSATIONS. [Boo* III.
three kinds more or less vaguely present wherever there are
tactile nerves. "The internal surface of the walls of the
abdomen feels clearly the motion of the intestines
After a cold injection, a very plain sensation of cold is
felt passing in the direction of the ascending and trans-
verse colon."* The pharynx, oesophagus,, and even the
stomach, feel with some degree of exactitude the passage,
warmth, and presence of food. And, in general, let us
review successively the innumerable internal sensations,
agreeable, painful, or indifferent, of organic life, those
constituting hunger, thirst, and repletion, those accom-
panying digestion, respiration, circulation, copulation, or
speech, those produced by wine, medicines, and various
substances introduced into the circulation, besides all the
spontaneous sensations, tinglings, itchings, shiverings, all
the various hardly definable pains which serve as symptoms
of different illnesses, all the special and very delicate sen-
sations of touch we meet with in the conjunctiva, the tongue,
and the interior of the nostrils, all the general and blunted
sensations of touch such as we find on the surface of the wound
after a recent amputation : we shall see that they are
sensations of contact, of cold or heat, of pleasure or pain,
more or less obscure, more or less ill-defined, more or less
spread about, the same in substance, but diversified by their
situation, the order of their phases, and the degree of
their intensity, f We shall find no other element in them,
* Landry, ibid. Longet, "Trait** de Physiologic," ii. 179.
f- Numbers of sensations which seem to have a special type and to be sui
generis, are composed of elementary sensations of contact. " If," says M. Landry,
" we cover a polished surface with a thin layer of talc and get a person who is not
aware of this to pass the tip of his finger over it, he will imagine he is touching
a greasy or oily body. . . ." Again, if we sprinkle some drops of water on a
marble table, and then, with our eyes shut, place the tip of a finger alternately
on the dry and the wet spots, we shall not be able to distinguish one from the
other. _ There is no special sensation, then, of damp or stickiness, but a compound
sensation of touch. " This sensation," says M. Gratiolet, "is developed when
the 8km detaches itself from something sticking to it, as, for example, a surface
covered with diachylon. It is most clear and distinct at the moment the adhesion
comes to an end, and the skin which had been drawn by the surface suddenly
returns to its proper state. From this sensation, when it is strong, comes the
idea of viscidity ; when slight, that of humidity. The contrary notion of dryness
is derived from an absolute want of adherence. This is so far the case that when
CHAP. II.] SENSATIONS OF SIGHT, ETC. 139
and, by this first reduction, we bring tactile sensations under
three types, and three only.
These types are not only distinct, but separable ; each of
them, as far at least as sensations of the skin are concerned,
may severally be lost, while the other two are retained.*
In some cases the sensation of pain only is lost. Patients
still perceive the other cutaneous sensations, such as heat,
contact, tickling, and can recognise the touch of a finger,
the brushing of a quill, the contact of a pin ; but if, in the
same spot, we prick them with the pin, it occasions no pain.
" I can feel/' said one of them, " that you prick and pinch
me, but you do not hurt me." This is carried so far that
sometimes the application of a white-hot cauterizing iron
gives no pain. A girl, suffering from hysteria, at the
Hopital Saint- Ant oine, upset boiling water over her hands,
and did not find it out till she saw large blisters rising.
In other cases, sensations of heat and cold are alone want-
ing. The patient then says : " I feel the form and con-
sistency of the body touching me, but cannot tell whether
it is hot or cold." Finally, in other cases, the sensation of
touch only is wanting. Here, for instance, the patient does
not feel small objects placed between the tips of his fin-
gers ; but " if pricked there, even superficially, it is plainty
felt." On the other hand, each type of sensation may sub-
sist alone, the other two being lost. Some patients who no
longer feel sensations of pain or heat, still feel contact at
the same point. Others, more numerous, no longer feel
sensations of pain and contact, but those of temperature
the hand is plunged in water we do not feel this humidity, nor when it is plunged
in oil do we feel its oiliness. In fact, bodies which an intermediate layer of
water cause to adhere to us, no longer adhere when plunged in water, and so with
bodies plunged in oil. . . . The skin is capable of receiving impressions on two
layers the one superficial, the other deep-seated. When the sensibility of the
deep-seated layer is brought into play, the sensation of pressure arises."
Gratiolet, "Anatomic Comparee du Systeme Nerveux," ii. 409. Landry,
"Paralysies," 159, 179.
* Beau, "Archives Generates de Medecine," Janvier, 1848. Delacour,
these, Janvier, 1850. Landry, "Recherches sur les Sensations Tactiles."
"Traite* des Paralysies." Axenfeld, "Des Nevroses," 332.
This separation has not been observed in the muscular sensations ; when any of
them disappear, the others disappear as well.
140
OF SENSATIONS.
[Boos TIT.
only. Others, finally, who can still feel pain, cannot feel
heat or contact. It is plain that each of these three types
of sensation has its special conditions, and when these
conditions alone are abolished, or alone preserved, the
isolated abolition or preservation of the type ensues.
Experience has discovered some among these conditions.
If a limb is chilled up to a certain fixed point, it retains the
sensation of contact, but ceases to experience that of pain :
for instance, " if we apply to the knee a mixture of pounded
ice and sea-salt, in the proportion of two parts of ice to
one of salt, the skin becomes bloodless, and we may caute-
rize the limb without the patient feeling any other sensa-
tion than that of the pressure of the iron/' Thus, the sen-
sation of pain is subject to a special condition ; to produce
it, the circulation of the blood, and therefore the molecular
wastings and repairs of the nerve, must go on with a cer-
tain degree of speed. With a less degree the nerve is no
longer capable of the special type of action which arouses
the sensation of pain, though it may still be capable of the
special type of action which arouses the sensation of pressure
and of contact. We see that the sensation of pain requires
for its production a condition, additional to those required
by the sensation of contact ; hence it follows that it may
readily be abolished without inducing the abolition of the
sensation of contact, and that the reverse is not the case ;
this is in conformity with experience. Persons who have
lost all sensations of pain frequently retain sensations of
contact ; but very seldom do persons who have lost sensa-
tions of contact retain those of pain.*
This instance puts us in the track of the needed expla-
nation. In fact, we have no need to suppose, with many
physiologists, that there are three kinds of nerves intended
to transmit impressions of contact, of heat and cold, and of
pain respectively ; each of the three classes being capable of
being paralyzed singly, and of thus cutting away from us
* Axenfeld, ibid. 332. " The inverse case is rarely seen ; when the sense of
touch is lost, that of pain is lost at the same time, or, in other words, the exis-
tence of anaesthesia, strictly so called, almost invariably implies that of analgesia."
CHAP. II.] SENSATIONS OF SIGHT, ETC. 141
one kind of sensation without the other kinds being thereby
abolished. The only thing which the facts attest is, that
the three kinds of sensations have special conditions, and
that these conditions may be singly destroyed. What are
these conditions? We may conceive many kinds. They
may be anatomical : this is the answer of the physiologists,
of Landry, Brown -Sequard, and Lhuys. In fact, it is suf-
ficient for the explanation of these isolated abolitions that
there be three kinds of nerves ; this solution is a manifest
one, we are tempted to adopt it. But there are others,
for the presence of a special nerve does not necessarily fol-
low from the fact of a special condition. There are two
other possible explanations. First, the condition may be a
special state of the same nerve, which would appear to be the
case from the experiment in which the frozen knee becomes
bloodless. Secondly, the condition may be a special state
of the parts surrounding the nerve, and through which the
external stimulus acts on the nerve ; in this case, the same
nerve, under the influence of the same external stimulus,
would transmit different sensations, according as the parts
between it and the stimulus were in different states. These
last solutions are more abstract, but they agree better with
the facts.
Weber's experiments appear to me conclusive as to
this."* If we dip into cold water a large nervous trunk, for
instance, the cubital nerve, where it springs from between the
two bones at the elbow, we find, in accordance with a well-
known law, a sensation in the arm and two last fingers of
the hand, occasioned by the nervous action going on at the
elbow ; now this sensation is not of cold, but simply of pain.
Consequently, when we have a sensation of cold, it is not
* Article Tastsirm, 498, in " Handbuch der Physiologie, " by Rudolf Wagner.
Of. Pick, "Anatomic und Physiologie der Sinnes Organe," 28, 30, 42, 43. From
the anatomical structure of the organs of touch, he shows, by approximation and
hypothesis, the different types of action which excite in the same nerve different
sensations, that of heat or cold, that of pressure or contact. " It is probable that
the stimulation of the nerves, in the sensation of heat or cold at the sensible
periphery of the skin, is not immediately developed by a change of temperature of
the nervous substance itself, but by the simultaneous changes supervening in the
mechanical relations of the terminal corpuscles."
142
OF SENSATIONS.
[BOOK III.
owing to the immediate action of cold on the nerve ; for it was
not felt just now, when the cold was acting immediately on
the cubital nerve. In order to feel it, the cold must act in-
directly; that is to say, through certain parts adjacent to
the nerve, certain organs disposed for this purpose ; these
act directly on the nerve ; the cold modifies them, and their
modification impresses on the nerve a special type of action,
which excites in us the special sensation of cold. If, on the
contrary, without paralyzing the nerve, we simply destroy in
these adjacent parts the property they have of impressing
this rhythm of action on the nerve, we shall cease to have
the special sensation of cold ; when the cold begins to act
on the nerve, it will no longer excite the special sensation
of cold, and will only excite, as we found just now in the
case of the cubital nerve, the sensation of pain. This is
what happens in certain illnesses. M. Axenfeld writes
as to this " With ataxic persons, whose cases are among
those in which want of sensibility is most complete, I
have often observed that cold was disagreeable without
its being recognised as cold. When we question them
as to the nature of their perception, all we can get
from them is, ' It hurts me/ >} We are led to the same
conclusion by studying the sensations of persons whose
bodies present large cicatrices, consequent on amputa-
tions or other wounds. " The parts of the skin/' says
Weber, " in which the tactile organs have been destroyed,
and are not completely reproduced, cannot distinguish
heat and cold." Similar experiments point out the pre-
sence of similar media in the case of the sensation of
pressure. If the cubital nerve between the two bones of
the elbow be pressed with the finger, the sensation in the
fingers and forearm is not of pressure, but solely of dull
pain. '' Therefore/' says Weber, " the sensation of pressure,
and the power of distinguishing its numerous and different
degrees, are only possible when the pressure acts on the
organs of touch, and, through them, on the extremities of
the tactile nerves ; this sensation does not arise when the
tactile nerves are directly compressed/' Consequently, the
CHAP. II.] SENSATIONS OF SIGHT, ETC. 143
sensation of pressure has for its special condition, not the
pressure of the nerve, but a certain modification of certain
organs or parts surrounding the nerve. If these organs be
alone destroyed, or their capacity for undergoing this modi-
fication be alone suppressed, the sensation of pressure will
alone be abolished.
Thus, in all cases, what is excited in us is a special type
of action in the nerve, and what excites this special type of
action in the nerve is a special modification of its appen-
dages and dependent parts. Consequently, to explain the
three kinds of tactile sensations, and to comprehend how
they may be singly abolished, there is no necessity of sup-
posing them excited in us by distinct nerves of three different
kinds : this is a gratuitous hypothesis which no vivisection
or microscopic observation comes in to confirm. It is enough
to admit that the same nerve or group of nerves is capable
of many different types or rhythms of action, and that each
of these rhythms is directly excited by the special modifi-
cation which the external agents impress on the parts sur-
rounding the nerve, whether on the tubes containing it, or
on the blood washing it, or on some other of its internal ac-
companiments .
It is not impossible to form a notion of the differences
of these rhythms. " Each tactile nervous fibre/' says Fick,
" can only transmit one and the same sensation which is
capable only of degrees But ordinary external sti-
muli do not arrive at these isolated elementary fibres;
they come in contact with a group of fibres taken together.
We may suppose that heat reaches these fibres in a different
order from pressure." " In fact, the nearer we draw to the
true elementary sensation, the more does the difference be-
tween the sensation of heat and that of a mechanical sti-
mulus seem to vanish. For instance, we can hardly dis-
tinguish a prick with a very fine needle from the touch of a
spark of fire." There is a further analogy; we know that
the sensations of heat and cold, like those of pressure,
become, when carried beyond a certain point, pure pain.
" Lastly, place on the skin some imperfectly conducting
144
OF SENSATIONS.
[BooK III.
body ; for instance, a piece of paper, pierced with a hole
of from 2 to 5 millimetres in diameter ; through this hole
apply to the skin, first, a mechanical stimulus, a pointed
piece of wood, a pencil or a flock of wool ; then, a heated
stimulus, such as the radiation from a piece of hot metal."
The two sensations, when thus limited to a minimum of
nervous elements, are so similar that the subject of the ex-
periment frequently mistakes the sensation of heat for one
of contact, and that of contact for one of heat. On the
contrary, when the nervous elements are numerous, as when
a large surface of the skin is subjected to the same experi-
ments, there is not this confusion. Plainly, then, here as
before, the ordinary sensation is a whole ; and, here as
before, two whole sensations may be apparently irreducible
to one another, though their elements may be the same ;
for this it is enough if the little composing sensations
differ in number, magnitude, order and duration; their
wholes form masses indivisible by consciousness, and seem
simple facts, differing in essence and opposed in quality.
It is very probable that the sensation of pain is no more
than a maximum ; for all the others, pressure, tickling, cold,
heat, change into pain when carried beyond a certain limit.
It is very probable that the sensation of pressure only
differs from contact because in pressure " the terminal cor-
puscles of the deep-seated system are also engaged, while
in contact they are not so."* The sensation of tickling is
most probably nothing more than a high degree of the sen-
sation of touch ; for, writes M. Axenfeld, " I have always
found it disappear with the sensation of touch. " And, in
fact, the contact producing it, though apparently feeble, is
actually excessive ; the feather of the quill, or the piece of
string which, when drawn slowly along the cheek or across
the nose, grazes imperceptibly the extremity of a nervous
papilla, evidently excites considerable activity in the ter-
minal molecule of the papilla, for the sensation is a most
* See Fick and Gratiolet at the places mentioned. Cicatrices have no sensation
of heat, and only a dull sensation of pain, but they retain the sensation of pres-
sure. This arises from the terminal epithelial corpuscles being lost, while the
deep-seated corpuscles of Pacini are still there.
CHAP. II.] SENSATIONS OF SIGHT, ETC. 145
vivid one and lasts for some seconds after the touch. The
alteration of equilibrium in the nerve indicated by it is greater
and slower in disappearing than when a pressure drives back
uniformly a whole group of papillae ; if the whole displace-
ment of flesh is then much greater, the relative displace-
ment of the nervous molecules is much less. This is why
the final sensation, if of less extent, is far more vivid.
To sum up ; all that observation shows us in the nerves of
touch, are different 'systems of transmissible molecular dis-
placements. Composed of similar elements, they constitute
dissimilar types or rhythms ; undefinable by us in the present
state of science, they are, like all displacements, definable
in themselves, by the speed, magnitude, and order of their
elements ; and we may admit that, according to the order
of their elements, they arouse in us sensations, sometimes
of temperature, sometimes of contact or pressure ; that at
their minimum of speed and magnitude, they arouse feeble
sensations of pressure, contact, and temperature; at their
maximum of speed and magnitude, they excite in us the sen-
sation of pain.
V. Let us attempt to cast a general glance over all these
facts. A sensation of which we are conscious is a com-
pound of more simple sensations, which are themselves
composed of others still simpler, and so on. Thus the sen-
sation produced by a harmony of thirds, ut mi, is made up
of two simultaneous sensations of sound, ut and mi. Again,
the sensation of ut, like that of mi, is made up of a com-
paratively strong sensation, that of ut, with the addition
of other comparatively feeble simultaneous sensations,
those of the superior harmonics. As to this comparatively
strong sensation and these comparatively weak ones, each is
made up of shorter successive sensations, which, when iso-
lated, are still perceptible by consciousness, and whose num-
ber is equal to that of the vibrations of the air divided by
two. Each of these little sensations is, in its turn, composed
of two successive elementary sensations, which, taken singly,
are not perceptible to consciousness. Finally, each of these
elementary sensations is itself an infinite series of successive
L
U9 OF SENSATIONS. [Boos III.
sensations, equally imperceptible to consciousness, infinitely
short, and increasing from a minimum to a maximum
through an infinite number of intermediate stages. The
whole results in the sensation of the chord ut mi, a com-
pound of the fifth degree, just as a product in organic
chemistry. So, again, the sensation of white is composed
in the first place of as many partial and simultaneous sen-
sations of white as there are nervous fibres excited in
the retina. Secondly, every partial sensation of white is
constituted by simultaneous sensations of two, or more than
two, complementary colours, for instance, yellow and indigo.
Thirdly, the sensation of yellow, like that of indigo, is made
up of three elementary and simultaneous sensations of colour,
red, violet, and green, each having a particular degree of
intensity. Fourthly, each of these three elementary sensa-
tions is composed of successive and continuous sensations of
the same colour, sensations still perceptible to consciousness,
and so numerous that there are at least a million of them in
a second. Fifthly, each of these successive sensations, so
prodigiously short, is, according to all analogies, composed,
like those of sound, of still shorter successive sensations,
imperceptible to consciousness, like the primitive sensations
of sound. Finally, if we follow out our analogies to the
end, we are led to conceive the sensation excited by each
elementary wave of ether on the model of the sensation
excited by each elementary wave of air, that is to say, as an
infinite series of successive sensations infinitely short and
increasing from a minimum to a maximum through an infi-
nite number of degrees. Such is the sensation of white, a
compound of the fifth or sixth degree.
This analysis brings three important principles to light.
The first is that two successive sensations which, singly,
are insensible to consciousness, may, when combined, form
a total sensation which consciousness perceives. The
second is that a sensation indecomposable by consciousness,
and apparently simple, is a compound of successive simul-
taneous sensations which are themselves highly complex.
The third is that two sensations of the same kind and
CHAP. II.] SENSATIONS OF SIGHT, ETC. 147
differing only in the magnitude, order, and number of their
elements, appear to consciousness as irreducible to one
another, and as possessed of special qualities absolutely
different. Armed with these three principles, we can con-
ceive the nature and diversity of the sensations of the other
senses. In accordance with the second and third, smells,
which like the colour white, appear simple sensations,
are, like white, compound sensations^ and the different
smells, which like different tones, seem irreducible to one
another, are, like these different tones, wholes, which, com-
posed of the same elements, differ only in the magnitude,
order, and number of those elements. We may form the
same conclusion with respect to tastes, and the sensations
of touch. But here a difference appears. With smells and
tastes an advance may be made which cannot be made
with sensations of touch. An idea may be formed of the
elementary sensations of which sensations of smell and taste
are constituted, but not of those of which tactile sensations
are constituted. We prove that the special and imme-
diate antecedent which sets the olfactory nerves and gus-
tatory nerves in action is a system of molecular displace-
ments ; we conceive this system of displacements to be
represented in the nerves by a corresponding system of
nervous actions, and to represent itself to us by a corre-
sponding system of elementary sensations of taste and
smell ; we define, to a certain extent, these unknown
elementary sensations by saying that they correspond to
molecular movements of chemical action, as the known ele-
mentary sensations of hearing or sight correspond to waves
of the undulations of air or ether. There is nothing
similar in the case of touch ; we have no means of deter-
mining or conjecturing the rhythm of action impressed on
the tactile nerves and transmitted by them to the nervous
centres. The elementary nervous action, and consequently
the elementary tactile sensation, remain beyond our grasp.
All we know is that there is such an action, and therefore
such a sensation ; for whatever be the stimulus, the tactile
nerve and. the centres it is connected with always act
L 2 *
148 OF SENSATIONS. [BOOK III.
alike and in a way peculiar to them : their rhythm of
action is special arid unalterable ; this is proved by the
rhythm invariably exciting in us the same kind of sensa-
tion, and from this kind of sensation being excited by it
alone.
Here are great gaps ; they will only be filled when phy-
siology is sufficiently advanced to determine the form and
speed of the molecular movement, whose repetition consti-
tutes nervous action. Meanwhile the theory of sensation is
like a building in part completed, and in part planned out.
Still this incomplete construction is sufficient to give us
an idea of the whole. We see that the innumerable sen-
sations which we refer to one sense may be reduced in
each case to an elementary sensation whose different
groupings make up the different sensations of that sense.
We conceive, in accordance with the three principles laid
down, that the elementary sensations of the five senses may
themselves be wholes, composed of the same elements,
without other difference than that of the number, order,
and magnitude of these elements, and therefore, like the
distinct sensations of hearing or sight, they may be reduced
to a single type. If so, there would be but one elementary
sensation capable of various rhythms, as there is but one (
nervous texture capable of various types."* And in fact,
whatever may be the structure of the nerves and nervous
centres whose action excites a sensation, however various
this structure may be supposed, that which is transmitted
from one end of the nerve to the other up to the ultimate
nervous centre, is never more than a molecular displace-
* Fick, "Lehrbuch der Anatomie und Physiologic der Sinnesorgane," 5.
Der Erregungsvorgang, welche Form er auch immer haben mag, ist in alien ner-
vosen Elementen gleicher Art, also ins besondere, in alien Nervenfasern, derselbe,
sei dieser Faser im Him, im Ruckenmark, oder in einem peripherischen Nerven-
stamm. . . . Indessen ist doch sehr warhscheinlich, dass der Erregungsvorgang
in den nervosen Elementen in gewissen Drehungen oder Umgruppirungen eiec-
tromotorischen molecule besteht.
See also Dr. Onimus, " De la Vibration Nerveuse et de 1'action reflexe dans
les Phenomenes Intellectuels."
Many physiologists admit that this displacement of the nervous molecules may
be compared to a vibration or to the swing of a pendulum. At all events, there
is an order of positions, which is altered, and then re-established.
CHAP. II.] SENSATIONS OF SIGHT, ETC. 149
merit, more or less rapid, extensive, and complex. A particle
had a certain situation with respect to others ; this situa-
tion changes, that is all ; at the limit of all the sciences
relating to bodies we invariably find mechanics. So that
the different nervous actions which excite different sen-
sations, can only be conceived as systems of movements.
Thus all these actions, though differing in quantity, are the
same in quality. Now since, by the known correspondence
between the sensation and the nervous action, sensations
different in quantity are the same in quality, we arrive, by
deduction, at the result foreshadowed by analogy. At
the foundation of all bodily events we find an infinitesimal
event, imperceptible to the senses, movement, whose degrees
and complications constitute the rest, whether the phe-
nomena be physical, chemical, or physiological. At the
foundation of all moral events, we guess the presence of an
infinitesimal event, imperceptible to consciousness, whose
degrees and complications make up all the rest, sensations,
images, and ideas. What is this second event, and can we
reduce one of these events to the other ?
Meanwhile we have reached the foundations of human
knowledge, and are capable of estimating their solidity. We
have seen that our senses are idioms, of which four are
special and the last general. A sensation is a mental re-
presentative, the internal sign of the external fact exciting
it. The special sensations of sight, hearing, smell, and
taste are delicate and limited representatives, each of which
severally translates accurately, by its characteristics, a special
order of external facts. The general sensations of touch
are coarse universal representatives translating, by their
characteristics, nearly all the orders of external facts.
Thus, every normal sensation corresponds to some external
fact which it transcribes with greater or less approximation,
and whose internal substitute it is. By this correspondence,
internal events agree with external, and sensations, which
are the elements of our ideas, find themselves naturally and
beforehand adjusted to things, which adjustment will, further
on, enable our ideas to be in conformity with things, and
150
OF SENSATIONS.
[BOOK III.
consequently true. On the other hand, we have seen that
images are substitutes for sensations, past, future, or possible,
that individual names are substitutes for images and sen-
sations momentarily absent, that the more simple general
names are substitutes for images and impossible sensations,
that the more complex general names are substitutes for
other names, and so on. It seems then that nature has
undertaken to provide in us representatives of her events,
and has effected her purpose in the most economical way.
She has provided, first, the sensation which translates the
fact with more or less precision and delicacy ; then, the
surviving sensation capable of indefinite revival, that is to
say, the image, which repeats the sensation, and consequently
translates the fact itself; then, the name, a sensation or
image of a particular kind, which, by virtue of its acquired
properties, represents the general character of many
similar facts, and replaces the impossible images and sensa-
tions which would be necessary to translate this isolated
character. By means of this correspondence, of this repe-
tition, and this replacement, external facts, present, past,
future, special, general, simple, or complex, have their in-
ternal representatives, and this mental representative is
always the same internal event, more or less compounded,
repeated, and disguised.
CHAP. L] FUNCTIONS OF THE NERVOUS CENTRES. 151
BOOK IV.
OF THE PHYSICAL CONDITIONS OF MENTAL EVENTS.
CHAPTER I.
OF THE FUNCTIONS OF THE NERVOUS CENTRES.
I. WE must stop here and change our route ; we have
come to the end of psychological analysis; let us see how
far physiological analysis will carry us.
We have explored, as geologists, a great country, from
its highest peaks to its seaboard, and, through all the
accidents of surface, have recognised one and the same
stratum supporting all the different varieties of soil. From
our most abstract ideas to our crudest sensations, we have
constantly found the same fundamental layer; ideas are
sensations or images of a certain kind ; images themselves
are sensations capable of spontaneous revival. At the
foundation of all these, we invariably find the sensation.
But, when we come to the sensation, we are at the limits of
the mental world ; between it and the physical world there is
a gulf, and, as it were, a deep sea ; we can no longer make our
accustomed borings ; the water prevents us from examining
whether the layer we have traced from end to end of the land
goes on beneath it to rejoin the other continent. In five
places, on the territory of the five senses, we have attempted
to step over the ordinary bounds ; with respect to the sensa-
tions of sight and hearing, we have pushed on to a conside-
rable distance ; with those of taste and smell, some advance
has been made ; and we see that, later on, a similar one may
be accomplished with sensations of touch. From all these
indications, we have concluded that the sensations of each
152 PHYSICAL CONDITIONS OF MENTAL EVENTS. [BOOK IV.
sense, and probably those of the different senses, though
apparently differing in quality, differ in quantity only, that
the same elementary sensations may, by their differences of
number, intensity, and proximity, make up whole sensations
which consciousness pronounces irreducible to one another,
and which therefore, different as they may apparently be, pro-
bably comprise one and the same fact, a kind of primitive rock
whose different aspects are owing to the different depths of the
water covering it. We have further proved that this rock,
though invisible at a certain depth of water, still subsists
there and is indefinitely prolonged, since at a certain degree
of brevity or weakness, the sensation, though imperceptible
to consciousness, is nevertheless real, and is found to be
made up of infinitesimal elements. Beyond, then, the
pyschological world observable by consciousness, there ex-
tends to infinity a pyschological world to which consciousness
does not attain. Here then we part from consciousness,,
which can teach us nothing further, and pass to the other
continent, to see if anatomy and physiology will not, on
their side, indicate to us some projecting rock, con-
necting itself with ours, beneath the obscure sea which
appears for ever to separate the two countries.
II. Let us look then for the physical facts on which our
mental events depend, and first, for the conditions of sen-
sation. These are direct or indirect, and make up a chain
whose earlier links act only when the last one is affected.
Let us trace this chain. In the first place, there is
the physical external event, the undulation of air or ether,
the chemical action of the liquid or volatile body, the me-
chanical pressure, the change of temperature, which by
dilatation or contraction of the parts arrives at affecting the
nerve. This condition is plainly but an accessory and
distant one. Though the nerve be so constructed as to
translate more specially external movements of a certain
type, it has its own type of action ; it is a spring which,
however it be set going, works in one way.* The optic
* Mueller, "Physiology" (tr. Baly,) ii. 1069,
CHAP. L] FUNCTIONS OF THE NERVOUS CENTRES. 153
nerve when excited gives no other sensations than those of
light; its various stimuli result in the same effect. An
undulation of ether strikes it, and we have sensations of
colour. It is excited by compressing the eyeball, and we
see brilliant circles, which are termed phosphenes. It is divided
in a surgical operation, and at the moment of its section,
the patient sees sudden large bodies of light. An electric
current is applied to it, and we see vivid flashes of light.
Digitalis is absorbed into the blood, and the blood so altered
excites in it sensations of flickering light. So again the
acoustic nerve gives no other sensations than those of sound,*
whatever be the external event which sets it in operation,
whether an undulation of air, electricity, irritation of the
blood, or a narcotic absorbed into the blood. So it is with
the other senses, and notably with that of touch. The
tactile nerves serve better than any others to prove this ; for
they are excited by a number of different external events,
mechanical contact or pressure, the chemical action of
caustics, of the air, and blood, change of temperature, un-
dulations of air or ether, section with the bistoury ; their
action invariably results in a sensation of contact, or pressure,
of temperature, or of pure pain.
Not only has each kind of nerve its special action, but
the action of each kind is different. The external event
may be the same, but, if it sets in motion nerves of different
kinds, the sensations excited will be different. The same
electric action arouses, according to the nerve it sets in
action, here a sensation of light, there of sound, elsewhere
again one of shock or of pricking. The same violent blow
arouses a sensation of pressure and pain through the tactile
nerves, of light through the medium of the optic nerve, of
sound through the medium of the acoustic nerve. The same
narcotic, introduced into the blood, arouses flashings when
acting on the optic nerve, ringings when acting on the
* That is, in the Limacean branch. See Flourens's experiments. On the
other hand, it is sensible to pain in the vestibular branch ; this then belongs to
the group of tactile, nerves.
154 PHYSICAL CONDITIONS OF MENTAL EVENTS. [BOOK IV.
acoustic nerve, formication when acting on the tactile nerves.
Thus each distinct kind of nerve has its individual and
distinct mode of action.
Hence it follows that all external excitants may be
absent ; if the nerve enters into action of itself, we should
have the same sensation in their absence as in their presence.
And, in fact, this is what happens : we experience without
their concurrence a number of sensations which we term
subjective or consecutive. They are especially numerous in
the case of sight ; the excitation of the optic nerve, and
the consequent sensation of colours or of light, lasts after
the undulation of ether has ceased to impress the retina ;
in such a case we continue to see, with closed eye-
lids, or with the eye turned in a different direction,
the object we were first looking at; according to the
circumstances, the object is uncoloured or coloured, of
persistent or of changing colour; and these illusions are
subject to known laws by which a multitude of singular
facts are explicable.* The same kinds of spontaneous
sensations are found in the sense of hearing. " Such
are the ringings and buzzings in the ears heard by persons
of delicate nerves and patients with disease of the auditory
nerve; such, too, is the noise heard in the ears for some
time after a long journey in a noisy vehicle."f Subjective
sensations of taste and smell are not so easy to detect. If
some patients are continually complaining of smelling fetid
odours, it is not certain that the origin of their sensation is
in the nerve itself; it may possibly be found in the nervous
centres. But there is nothing more common than sponta-
neous action of the nerves of touch ; it is enough to mention
neuralgia, strictly so called ; the simple action of the nerve,
in the absence of all appreciable excitants, arouses, main-
tains, and then revives the keenest and most various sensa-
tions of pain.
This is why, if the state of the nerve changes, though
* Helmholtz, " Handbuch der Physiologischen Optik." 2 me partie, 22-25.
t Mueller (tr. Baly), ii. 1072, 1210, 1310.
CHAP. I.] FUNCTIONS OF THE NERVOUS CENTRES. 155
the excitant continue the same, the sensation changes in
degree, or even in quality. For instance, if the nerve has
become unduly excitable, the least stimulus developes an
extreme action, and the sensation is of terrible intensity ;
this is the case with the unfortunate patients who suffer
from hypersesthesia of the optic, acoustic, or tactile nerves.
If, on the other hand, the nerve has become less excitable,
or has ceased to be excitable at all, the strongest stimuli
will only arouse in it weak or imperceptible sensations ;
this happens when the nerve is divided, tied, benumbed
with cold, or paralysed by illness. Finally, if the nerve has
become excitable in a different way, its action, though
induced by the same stimulus, is different, and the sensa-
tion is no longer the same; in indigestion or fever, all
kinds of food have an earthy or bitter taste. In short,
the direct condition of the sensation is the action or mole-
cular motion of the nerve ; neither external events nor the
other internal events of the living body matter much ; they
only act by means of the movement they excite ; in them-
selves, they do nothing ; they may be dispensed with. If
the action of the nerve were always spontaneous, as it
sometimes is ; if this action were still produced according
to the ordinary order and degree, the external world, and
all within us excepting the nervous system, might be anni-
hilated ; we should still have the same sensations, and
consequently the same images and the same ideas. Let us
look, then, more closely into this nervous action, since there
is no sensation without it, and since it is sufficient of itself
to excite sensation.
III. When a sensitive nerve commences to act, a mo-
lecular movement is propagated through its whole course
till it reaches the nervous centres.* The nerve is a con-
ductor, just as the air which transmits the oscillations of a
vibrating string, or the iron wire which transmits electric
action. Two experiments prove this. If it is compressed,
* This movement is produced in the central filament of the nerve, termed the
axis- cylinder. It is the only essential part of the nerve. Vulpian, "Le9ons
sur la Physiologic du Systeme Nerveux," p. 55.
156 PHYSICAL CONDITIONS OF MENTAL EVENTS. [BooK IV.
tied, or cut at any point between the nervous centres and
the spot excited,, there is no longer any sensation ; in this
case the nervous centres are intact, the terminal extremity
of the nerve acts as before; the central part of the nerve,
then, is what has ceased to act; therefore, it was previously
acting; therefore when, in consequence of a terminal ex-
citation, a sensation is produced, the nerve has acted in all
its segments and through all its course. On the other hand,
in all parts of its course, this action results in the same
effect.* At whatever point it may be irritated, the final
sensation is the same. This extends so far that sometimes
our associated images localize the sensation in parts which are
insensible or absent. "There are kinds of paralysis in which the
limbs are absolutely insensible to external irritations, though
the severest pains are felt there." The fact is, the nerves
which supply these limbs, though insensible at their ex-
tremities, are still irritable and irritated in the higher parts of
their course. For the same reason, any section, compression,
or irritation of a nervous trunk excites a sensation which
appears to be situated in the parts to which the branches and
terminal fibres of the trunk lead. If the arm be compressed
with a tourniquet till it is insensible to excitations from with-
out, and if the nervous trunk between the two bones of
the elbow be then pressed, a keen sensation will be felt
similar to that of an electric shock, and this sensation ap-
pears to be situated in the part whose nerves are benumbed.
Every one has heard of the illusions of persons who have
lost limbs. " These illusions persist and retain the same
intensity through the whole of life ; we may convince our-
selves of this by questioning persons who have suffered an
amputation a long time after they have undergone the ope-
ration. They are most vivid at the time of the inflammation
of the stump and nervous trunks ; the patients then com-
plain of very severe pains throughout the limb which they
have lost. After the cure there frequently remains for life
* Mueller, " Physiology" (tr. Baly), i.
nerves.
Of the laws of action of sensitive
CHAP. I.] FUNCTIONS OF THE NERVOUS CENTRES. 157
a feeling of formication, or even of pain, seated apparently
in the non-existent external parts. These sensations are not
vague,, for the patient feels pains or pricking in some par-
ticular spot, the heel, the sole, or the back of the foot, the
skin, &c. They end by becoming accustomed to it, and
finally cease to perceive it ; still, if attention be called to it,
the sensation reappears, and is often felt very distinctly in
the heel, the fingers, the sole of the foot, the hand/'' &c.
In many cases, after seven, twelve, or even twenty years,
the sensation is as plain as on the first day. We see that
for the purpose of exciting the sensation, the action of
nerve is itself accessory only ; it is only a medium ; if the
molecular movement which is propagated along its course is
effective, it is simply because it excites another molecular
movement in the nervous centres ; just as the electric action
that runs along the telegraph wire has no importance till
it arrives at its destination and moves the needle of the
dial-plate.
What is this molecular movement which is propagated
throughout the conducting nerve ? We cannot tell ; all we
know are some of its characteristics.* We prove that in
the sensitive nerves, though its usual course is in the direc-
tion of the centres, it may also be directed towards the ex-
tremities. If we engraft the end of a rat's tail into the skin
of its back, and then, when the grafting process is com-
pleted, cut the basilary portion of the tail about a centimetre
from the root ; after some months, if the grafted tail be
pinched, the animal feels it, and turns round to bite ; the
irritation of the nerve, which, before the operation, acted in
a centripetal direction, now acts in a centrifugal one. We
can further prove that the molecular movement is the same
in a motor nerve and in a nerve of sensation. For if we
unite end to end the fibres of a motor nerve, as the hypo-
glossal, with those of a sensitive nerve, like the lingual, on
the one hand, the irritation of the sensitive nerve is visibly
* Vulpian, op. cit. 102, Experiments of Helmholtz, ib. 283 ; of Bert, ib.
287 ; of Philipeaux and Vulpian, ib. 290.
158 PHYSICAL CONDITIONS OF MENTAL EVENTS. [BOOK IV.
propagated along the motor nerve, and produces muscular
contractions ; while, on the other hand, it is very probable
that the irritation of the motor nerve is propagated along
the sensitive nerve, and excites pain. We finally establish
that " every excitation applied to any part of the length of a
nervous fibre is immediately and simultaneously transmitted
in two directions, centripetal and centrifugal/" and we have
some indications as to the velocity of this transmission.*
The conclusion from all this is, that "the intimate phe-
nomena caused by an excitation of the nervous fibres are
certainly identical, whether those fibres are motor, sensitive,
or sympathetic." If the final effect be different, it arises
from the different ramifications of the nervous fibres, some
being in connexion with muscles, and others, with particular
parts of the nervous centres ; just as similar wires, which
are the theatre of similar electrical phenomena, produce,
according to the apparatus they are connected with, some-
times the ring of a bell, sometimes the displacement of a
needle, sometimes the impact of a handle.
Hence it follows that the immediate condition of the sen-
sation is found in the nervous centres ; where there is pro-
duced a molecular movement of unknown nature, without
which the sensation cannot arise, and which is of itself
sufficient to give rise to it. And this, in fact, is what
happens in very many cases. Many sensations arise in us
without the intervention of the nerves, and by the simple
excitation of the nervous centres. Such are hallucinations,
strictly so called, of which we have seen numerous examples, f
and, in which cases, we can, on most occasions, neither prove
nor conjecture the existence of any irritation of the extremity
or any portion of the course of the nerve. I have described
the visions which precede sleep, and which any one may ob-
serve in himself ; in such a case, we close our eyes, we discard
all excitation from without, we pacify all the nerves, and, as
* According to the most recent experiments, it is twenty-nine metres a second
in the nerves of the human body. It varies with the surrounding temperature,
and is not uniform throughout the length of the nerve.
t Book ii. chap. i.
CHAP. L] FUNCTIONS OF THE NERVOUS CENTRES. 159
might be expected, in the universal stillness of all the con-
ductors which usually set the brain in action, our vague
and feeble images become intense and clear ; they are
turned into sensations ; we dream, we see absent objects.
Excepting in the absence of objects and the inaction of the
nerves, our state is the same then as in the cases of ordinary
sensation ; the brain is then acting as in the case of ordinary
sensation; and it alone is acting, owing to the absence of
objects and the inactivity of the nerves. When it is excited
directly and alone, hallucinations are produced, that is to say,
spontaneous sensations with their associated images ; and this
is what happens when the brain is inflamed, or irritated by
haschich. Besides, medical observers have recorded many
instances of patients some of whose nerves have been more
or less completely destroyed, though the hallucinations cor-
responding to these nerves have been perfect."* Esquirol men-
tions among other cases that of " a Jewess, thirty-eight years
old, blind and insane, who nevertheless saw the most ex-
traordinary objects. She died suddenly ; I found the optic
nerves atrophied from their point of intersection to the points
where they enter the eyeballs ; in this case the transmission
of impressions was clearly impossible." "Two persons had
each of them lost ai} eye by phthisis of the eyeball, and in
their cases hallucinations were produced as readily on the
side on which the eye was lost as on that of the sound
eye/' tf We have at present in the Salpetriere," says
Esquirol, " two women who are absolutely deaf, and who
have no other delusion than that of hearing the voices of
different persons, with whom they dispute night and day."
Strictly it might be objected that in these instances the
central and as yet intact portion of the nerve is the starting-
point of the irritation ; but this is not probable ; the hallu-
cination is too systematic ; if it proceeded from the nerve,
it would be requisite that its different fibres should
enter into action in the complex order and with the exact
* See Griesinger, "Trait6 des Maladies Mentales," 101-2, for numerous
examples.
160
PHYSICAL CONDITIONS OF MENTAL EVENTS. [BOOK IV.
degree which an external excitant could alone impose on
them. " A direct irritation/' says Griesinger, " may cer-
tainly occasion luminous patches, globes of flame, and
coloured figures in the retina, but not complex forms, such as
houses, men, trees; it may determine buzzings and noises,
loud or otherwise, in the ear, but not actual words or tunes."
The distinction is still more clearly marked in the hallu-
cinations following the use of the microscope ; the details
of which I give from a letter written me by one of our most
distinguished micrographists, M. Robin. "I have remarked,"
says he, " that after having looked through a microscope
for some time, and especially when I have been aided by a
strong light, the figures of the objects observed persist when
I close my eyes. They still persist whether I direct my eyes
on the mahogany table holding my instruments, or on my
drawing-board, which is of a greyish blue, or on my drawing
paper. They persist for about two or three minutes, oscil-
lating about in a narrow circle ; after diminishing in size
and then disappearing they reappear, though paler ; after
two or three reappearances, more and more faint, they cease
to reappear. They disappear more readily when I rest my
eyes on a white paper, than when I turn or rest them on
my table, which is of dark mahogany. I see them of a
greyish colour, just as the images of objects seen under
the microscope. These images are the shadow of the objects,
projecting itself on the retina, which is brightly lighted
up around them in the circular field of the microscope, just
like the Chinese shadows of the magic lantern" In my opinion,
adds M. Robin, it is not the retina which continues and
recommences to act in the absence of the object ; <{ it is the
cerebral centre of visual perception/' which having once acted,
recommences two or three times to act of its own accord.
" I do not think the external extremities of nerves of sen-
sibility, or organs of impression, are capable of such spon-
taneous action as to transmit the form, colour, &c. of an
object to the perceptive centre ; but, on the other hand, the
centre of perception itself may return spontaneously to a
preceding state of activity, under the influence of some
CHAP. I.] FUNCTIONS OF THE NERVOUS CENTRES. 161
temporary congestion of its vessels,, such as is produced by
the prolonged use of the microscope, or the ingestion of the
alkaloids of opium,, or of belladonna, absinthe, &c." In fact,
diseases of the eye with congestion of the retina, but un-
accompanied by meningitis, do not recall to the scene
images of this kind, but entirely different ones ; to arouse
these, there must be meningitis, the intoxication of opium or
absinthe, that is to say, irritation of the nervous centres.
To sum up, irritation of the nerves and that of the nervous
centres are recognisable by symptoms of marked difference.
" The first, which we may term pseudsesthesia of the peri-
pheral extremities, is characterized by luminous sparks and
flashes, by noises, ticklings/' and other isolated sensations,
not forming a system and not corresponding to any possible
combination of external characters. " The second, which
we may term pseudaesthesia of the perceptive centres/'' is
characterized by the persistence or revival of complete
images, like those of the microscope that is to say, by
hallucinations or spontaneous and organized sensations of
colour and relief, of harmonized and articulate sounds, cor-
responding to a possible combination of external characters.
IV. We have then finally settled that the necessary
and sufficient condition of the sensation and therefore of
images, is a certain action or molecular movement of the
nervous centres, that is to say, of the encephalon ; in fact,
all nerves of sensation terminate there, either directly, as is
the case with the cranial nerves, or indirectly, as the
rachidian nerves, through the medium of the conducting
parts of the spinal marrow.* We must now inquire, what
among the different parts of the encephalon are those
whose action is the necessary and sufficient condition of
sensation and of images ? For this purpose physiologists
employ vivisections, and their experiments are very decisive
in the matter. Let us first consider the pure sensation.
If the reader will examine a preparation of the encephalon,
* Brown- SSquarcl, "Journal de Physiologic ;" and see ante book iii. chapter 2'
p. 136.
M
162 PHYSICAL CONDITIONS OF MENTAL EVENTS. [Boos IV.
or at all events the figures of some large anatomical atlas,
he will find that the spinal marrow at its upper extre-
mity swells out into a bulb termed Medulla Oblongata or
rachidian bulb, with which the encephalon commences.
We may cut away from an animal the whole encephalon
excepting this bulb ; the animal will still execute a number
of systematic and automatic movements, which are termed
reflex, and which are produced by the different segments
of the marrow without the intervention of the encephalon.*
For instance, it swallows food, the muscles of its face
still contract in an expressive manner, it articulates vocal
sounds, and goes through all the movements of respiration ;
but it can no longer experience sensations strictly so called.
It utters cries, but mechanically only ; it no longer suffers
pain. Let a transverse section be made above the bulb.
" The bulb and marrow are then isolated from the encephalic
centre, just as if the brain and annular protuberance were
removed ; this is what I do to this rat. I now pinch its paw ;
you hear a short slight cry. I do so again : another similar
cry. I now wound deeply the rachidian bulb; I again
pinch a hind limb : there are reflex movements, but there
is no longer any cry Observe the character of the
cries you have just heard, they are reflex? cries, and very
different from cries indicating pain/' There is in the
bulb, as in the different segments of the marrow, a mechanism
capable of acting, either directly by the irritation of the
sensitive nerves it receives, or indirectly by the effect
of the sensations aroused in the other parts of the en-
cephalon. When the other parts are cut away, the bulb
continues to act, and the cry is produced, without any sensa-
tion having been excited. Let us next preserve, not only
the rachidian bulb, but also the part of the encephalon
adjoining it the Pons Varolii or annular protuberance
through which the fascia of the bulb pass, and remove the
remaining parts, that is to say, the cerebral lobes, the corpora
striata, the optic thalami, and the corpora quadrigemina.
* Vulpian, op. cit. 496, 510.
CHAP. I.] FUNCTIONS OF THE NERVOUS CENTRES. 163
" When this is effected on dogs and rabbits, they manifest by
violent agitation and plaintive cries, the pain they feel when
the trigeminal nerve is pinched, or when they are subjected
to keen external stimuli. If the protuberance be then
deeply wounded, there are no more cries or agitation,
even under violent pinchings ; and yet the circulation, re-
spiration, and other functions continue to be accomplished
for some time I have repeated M. Longef s ex-
periments, and have obtained precisely the same results as
his. This young rabbit has, strictly speaking, no brain,
neither corpora striata, nor optic thalami ; all there is
left in its skull are the annular protuberance, the rachidian
bulb, the cerebellum, and the corpora quadrigemina.* I
pinch its tail sharply ; you see it is at once violently agi-
tated. I pinch its ear, its lip ; similar agitation, and
similar cries. Can these cries be considered as reflex
phenomena ?" By no means. " You have seen animals
from which the whole encephalon, excepting the rachidian
bulb, has been removed ; these animals continued to cry
when pinched ; but what a difference between their cries
and those we hear when we have left the protuberance
intact ! In the first case, each excitation of a still sensible
part excited a short cry, single for each separate excitation,
always the same, and something like the sounds given out
by children's toys when pressed in a certain way in a
word, deprived of all kind of signification. There we have
the reflex cry. But here, with this rabbit, what a difference
we find ! When a sensible part is irritated the cry is not a
short but a prolonged one, unmistakably plaintive, and,
after a single excitation, the animal gives several successive
cries, precisely similar to the cries of pain which another
uninjured rabbit gives when it is subjected to sharp irrita-
tion/'f Hence action of the protuberance is the necessary
* Other experiments show that the cerebellum does not intervene in sensation ;
the functions of the corpora quadrigemina will be presently explained. Mean-
while this experiment may be considered as conclusive as if the cerebellum and
corpora quadrigemina had also been removed.
f Vulpian, op. cit. 541. Experiments of Longet.
M2
164 PHYSICAL CONDITIONS OF MENTAL EVENTS. [BOOK IV.
and sufficient condition of tactile sensations. It is also the
necessary and sufficient condition of sensations of hearing.
" A certain call made with the lips, or a rough purring noise
like that of an angry cat, will always startle an uninjured rat.
Now here is a rat from which the brain, strictly so called,
the corpora striata, and the optic thalami have been re-
moved. You see him he is very quiet ; I make the noise
I have just described, and the animal at once gives a sudden
jump. Every time I make a similar noise, you see a
similar jump. Those of you who have noticed the effects
of being so startled upon an uninjured rat will recognise
that they are of precisely the same character as we see
here."* Finally, the action of the protuberance is also the
necessary and sufficient conditions of sensations of taste.
" I have removed the cerebral lobes from kittens and
puppies ; and on pouring down their throats a concentrated
decoction of colocynth, I have seen them go through abrupt
motions of mastication, and contort their lips, as if to rid
themselves of a disagreeable sensation. The same move-
ments were observed in an uninjured animal of the same
species, when forced to swallow the same bitter decoc-
tion. ' v f There is, then, a special centre, the protuberance,
whose action is the necessary and sufficient condition of
many kinds of sensations. There are other similar centres
which perform the same office with respect to other sen-
sations. For the sensations of sight, they are the corpora
quadrigemina or bigemina. " Here is a pigeon whose
cerebral lobes are entirely removed, but whose corpora
bigemina remain ; when I suddenly put my hand near it,
it makes a slight movement of the head to avoid the threat-
ened danger. The sight then is retained. We have here
a phenomenon analogous to that which we noticed in the
case of the rat deprived of its cerebral lobes, when we in-
duced a sudden jump by means of certain sudden noises.
Here again we have an example of sensations without the
* Vulpian, op. cit. 548.
t Longet, "Traite de Physiologic," ii. 243. Vulpian, 548.
CHAP. L] FUNCTIONS OF THE NERVOUS CENTRES. 165
intervention of the brain strictly so called."'* If, on the
other hand, we leave intact the cerebral lobes, and injure
or destroy the corpora quadrigemina, the animal becomes
blind, preserving, nevertheless, all its ideas, its instincts,
and its other sensations. The corpora quadrigemina, then,
furnish by their action the sufficient and necessary con-
dition of visual sensations, and of visual sensations only.
As to sensations of smell, experiments have not yet
been made to determine the portion of encephalon whose
action is their necessary and sufficient condition; but all.
anatomical and physiological analogies lead us to the belief
that, for them, as for the other four kinds of sensations, there
is a centre, distinct from the cerebral lobes themselves.
When excited by the action of the sensitive nerves, the
cells of these centres perform their functions in an unknown
manner, and this special molecular movement, without
which there is no sensation, is in itself sufficient to arouse
the sensation.
V. It must be observed that we have here been dealing
with pure sensations, or with what physiologists call crude
unelaborated sensations, that is to say, with sensations un-
provided with the faculty of spontaneous revival, and
therefore with the faculties of being associated, of forming
fixed groups, and of furnishing means for the higher opera-
tions of intelligence. We must now look to another class of
experiments, and here again the concordance of physiology
with psychology is as complete as unforeseen. Psycho-
logical analysis had already separated the functions ; phy-
siological analysis separates the organs. The first placed on
one side pure sensations, on the other images or reviving
sensations ; the second puts on one side the corpora quadri-
gemina, the protuberance, and perhaps another ganglion,
whose activity arouses pure sensations, and on the other
side the cerebral lobes, whose action arouses images, that
is to say, reverberates, prolongs, and associates sensations.
If the reader will look again at a prepared encephalon,
* Vulpian, 557. Experiments of Flourens and Longet.
166 PHYSICAL CONDITIONS OF MENTAL EVENTS. [BOOK IY.
he will see that, from the anterior angles of the annnlar
protuberance, spring two large white columns, called
cerebral peduncles or crura cerebri, whose fibres terminate
in the swellings called optic thalami and corpora striata,
which are intermediate organs to the cerebral lobes and the
protuberance. In fact, other fibres start from these organs
and terminate in the cerebral lobes.* As to the cerebral
lobes themselves, they constitute, particularly in the superior
animals, the greatest part of the encephalon. In man they
are enormous, and occupy by far the largest part of the
cranium. Comparative anatomy has already foreshadowed
their use by showing us that in the animal series their
volume increases at the same rate as intelligence ; we shall,
moreover, find that their most important part is the outer
layer, composed of a grey substance ; and it is a no less sig-
nificant circumstance that, as we ascend the zoological scale,
this surface increases much more quickly than the volume
owing to the very numerous swellings and anfractuosities
which bend it into folds and are called circumvolutions.f
In man himself, atrophy of the cerebral lobes and absence
of circumvolutions are always accompanied with idiocy;
"when a brain is below a certain volume and certain
weight, it must necessarily have belonged to a person
affected with imbecility . . . ;" and, in general, if we compare
different races of men, " the volume of the encephalon is in
proportion to the degree of intelligence/' All these pre-
sumptions are confirmed by our operations on living ani-
mals; it is sufficient to resume the preceding experiments ;J
when we have removed the cerebral lobes, the rest of the
encephalon being intact, pure sensations still, as we have
seen, subsist; but they alone subsist. The animal still ex-
periences crude sensations of light by means of the corpora
quadrigemina, crude sensations of pain, contact, sound, and
* Vulpian, 652, following Koelliker.
t Broea, "Sur le Volume et la Forme du Cerveau, suivant les individus et
suivant les Races. Paris, 1861.
J Vulpian, 690. Flourens, 2 me edition, "Recherches Experimentales sur
les Propnetes et les Fonctions du Systeme Nerveux," 24.
CHAP. I.] FUNCTIONS OF THE NERVOUS CENTRES. 167
taste, by means of the protuberance. But these are bare sensa-
tions ; they are not, as in the normal state, accompanied and
clothed with associated images, which add to the sensation of
light notions of the relief, distance, and other characters of
the luminous object ; to the sensation of contact, notions of
situation, resistance, and form ; to the sensation of sound or
taste, the representation of a sonorous or savoury body.
Much less then, can these isolated sensations arouse the
associated images constituting memory and prevision, and
through them judgments, and all the assemblage of emo-
tions, desires, fears, and determinations developed by the
notion of approaching danger or of future pleasure.
Another consequence is the absence of instincts ; for in-
stincts are constituted by groups of images whose association
is innate. A beaver shut up in an enclosure in the Jardin
des Plantes, who collects pieces of wood and mortar to make
a dam of which he has no need in Paris, and of which he
has need in America, is an animal in whom are developed
a spontaneous system of images ; so, again, is a bird who
builds his nest in the spring; at the sight of straw, hair,
and wool, the notions of their combination and usage arise
in him without preliminary experience, without tentative
effort, in a fully constructed order, by an unacquired wisdom.
It matters little whether this order be, as with man, the
effect of a personal apprenticeship, or, as with the brutes,
the play of an hereditary mechanism ; it is invariably an
order of representations that is to say, of grouped images ;
and therefore, if the images are destroyed, it is destroyed.
This is what happens when the cerebral lobes are cut
away. " The animal loses all its intelligence." Though,
with the corpora quadrigemina and protuberance, it may
have retained crude sensations, it no longer has the images
which by their association with crude sensations give it the
notion of objects. " These objects continue to paint them-
selves on the retina ; the iris remains contractile, the optic
nerve excitable ; the retina remains sensible to light ; for
the iris contracts or expands accordingly as the light is
more or less vivid ; so the eye is sensible. And still the
168 PHYSICAL CONDITIONS OF MENTAL EVENTS. [Boos IV.
animal no longer sees " A pigeon thus operated
on " kept itself well upright ; it flew when thrown in the
air ; it walked when pushed on from behind ; the iris of its
eyes was very contractile; nevertheless, it did not see or hear,
it never moved spontaneously, it put on all the attitudes of
a sleeping or drowsy animal, and when roused from this sort
of lethargy, assumed the attitude of an animal waking
up When I let it alone, it remained calm and as it
were absorbed ; in no one case did it give signs of will. In
short, picture to yourself an animal condemned to perpetual
sleep, and deprived of the faculty of dreaming in this sleep."
In fact, all the images whose irregular concatenation forms
dreams, and whose regular concatenation forms the waking
state, were absent; all that remained were some few inter-
mittent sensations aroused by the experimenter, and, accom-
panying them, the dull tendencies and involuntary move-
ments consecutive to them. A hen lived ten months after
a mutilation of this kind, and, after the fifth month, was fat,
strong, and healthy ; but instincts, memory, prevision, and
judgment were gone. " I left her fasting on many occa-
sions for three whole days at a time, and then have put food
to her nostrils, have dipped her beak in grain, have placed
grain in the anterior part of her beak, plunged her beak in
water, placed her on a heap of corn. She did not smell, or
swallow, or drink, she remained motionless on the heap of
corn, and would assuredly have died there of starvation if I
had not taken on me to make her eat. I have twenty times
put pebbles instead of grain in her beak ; she swallowed the
pebbles as she had swallowed the grain. * Finally, when
she met with an obstacle in her way, she ran against it, and
the shock stopped her or shook her. But to run against an
object is not to feel it ; she never groped about or hesitated in
her progress She never took shelter, however in-
clement might be the weather ; she never defended herself
against the other fowls; she no longer knew how to fight
or to run away ; the caresses of the male bird were indifferent
* By a reflex movement.
CHAP. I.] FUNCTIONS OF THE NERVOUS CENTRES. 169
or unperceived by her. ... She ceased to peck with her
bill."
The same thing happens with other animals.* Frogs have
no longer any notion of eating a fly held to their mouths.
r 'The mole ceases to dig, the cat remains quiet even if
teased." All images, then, fail, and consequently, those
which serve as signs, and by which we have abstract ideas,
also perish. Thus all the operations which pass beyond pure
sensation not only those which are common to animals
with man, but also those which are special to man have,
for sufficient and necessary condition, an action of the
cerebral lobes. They are, then, attached to this action ;
they rise, perish, are altered, are accelerated and transformed
with it, and pathology here is in accordance with vivisection.
* Vulpian, 690. Landry, " Paralysies," 82.
If we take two frogs, one uninjured and the other deprived for some days of its
cerebral tubercles.
"Let them both be put on the floor, the first runs off at once and tries to hide
himself. The second, after a leap or two, becomes motionless and remains so.
When a noise is made near them, the first will sometimes turn round to see
where it comes from and sometimes run away, the second will give a slight start,
but will not move. If their paws are pinched they will both jump away, and
struggle if they are retained."
Let them both be put in a large basin of water.
The uninjured frog goes through several movements of swimming, and tries
to hide himself at the bottom of the basin. Meanwhile, the movements of respi-
ration have entirely ceased. After a time, it regains the surface of the water in
order to breathe, and tries to remain there, but having no hold exhausts itself in its
efforts to keep there. When pushed down to the bottom, it soon comes up again,
and if prevented from doing so, will attempt to come up at another part of the basin.
The frog deprived of its brain behaves very differently. The moment it is
placed in the basin it sinks to the bottom like an inert mass without attempting
to swim. Still, when stirred with a stick, it goes through the movements of
swimming, but at hazard and without object, and then becomes motionless and
sinks to the bottom. In its case the respiratory movements continue to be gone
through as in the air, with the single difference that the little membranous lid of
the nostrils is completely closed. The animal remains quietly at the bottom of
the basin without attempting to gain the surface to breathe, and without showing
the least uneasiness. The respiratory movements " become abrupt and few, and
the frog dies suffocated without having made any attempt to breathe, and
without appearing to have suffered.
" Thus the brainless frog does not know how to suspend respiration, and would
inspire water if the lid of the nostrils did not close automatically at the contact
of the liquid ; it does not suffer from asphyxia, is not aware of it, and does not
attempt to avoid it. Nothing, it seems to me, can better show than this experi-
ment both the real absence of perception, the absence of every intellectual phe-
nomenon, and the absence of will.
"I admit with M. Flourens that the brain properly so called is the seat of
perception, volition, and all intellectual phenomena."
170 PHYSICAL CONDITIONS OF MENTAL EVENTS. [BooK IV.
' ' All the organs/' says Mueller, " with the exception of
the brain, may either pass slowly out of the circle of the
animal economy or perish, without the faculties of the
mind undergoing any alteration. It is different with the
brain; any cause which disturbs its action slowly or sud-
denly, affects at the same time the mind Inflam-
mation of the brain is never unattended with delirium,
and at a later period with stupor; pressure on the cere-
brum, whether produced by depressed bone, foreign bodies,
serum, blood or pus, always gives rise to delirium or stupor,
according as there is or is not irritation with the pressure.
The same causes, according to the seat of their action, fre-
quently abolish the power of voluntary motion, or memory ;
and when the pressure is removed, the memory fre-
quently returns, and it has been observed that the chain of
thought was immediately resumed at the point where it
was interrupted by the injury. 1 "* After cerebral com-
motion " there is sometimes complete loss of intelligence.
In other cases the patient answers questions put to him,
but soon falls again into a drowsy state, his memory is
sometimes entirely, sometimes partially gone. Total for-
getfulness of a foreign language is one of the most usual
effects of this commotion Patients never recol-
lect how their accident has occurred ; if they have fallen
from horseback, they recollect perfectly having mounted
and got off, but never recollect the circumstances of their
fall. The effects of a lesion of the brain are in some ways
analogous to those brought on by old age ; the patient
preserves the recollection of recent impressions only, and
forgets those of earlier date. . . . "With some patients,
memory remains ever after imperfect ... In some particular
cases patients are unable to avail themselves of the right
word to express their ideas, the judgment is often im-
paired."f Other injuries indirectly affecting the brain
produce similar effects ; we know that people faint when
* Mueller, op. cit.' (tr. Baly) i. 817.
t Vidal, " Pathologic Externe," 750 citing Cooper.
CHAP. I.] FUNCTIONS OF THE NERVOUS CENTRES. 171
they have lost much blood, that drunkenness disorders the'
ideas, that narcotics produce stupefaction, haschich brings
on hallucinations, coffee developes a liveliness of mind,
chloroform and ether produce insensibility."* To sum up,
alteration of the cerebral lobes has, as a consequence, a
proportionate alteration of our images. If the lobes be-
come unfitted for some particular system of actions, some
particular system of images, and therefore some group of
ideas or of cognitions, is found wanting. If their action
becomes excessive, images of a more intense kind escape
from the repression ordinarily imposed on them by sen-
sations, and turn into hallucinations. If, in addition to
this, their action becomes disconcerted, images lose their
ordinary associations, and delirium is pronounced. If
their action be annulled, all images, and therefore all ideas
and cognitions, are annulled ; the patient falls into the
state of torpidity and deep stupor which we find caused in
animals by cutting away these lobes.
VI. We must now determine on what part of the cere-
bral lobes images depend. These lobes are made up of
a white substance and grey cortical matter; and all in-
ductions concur in attributing images to the action of the
grey cortical matter. In fact, the extent of this cortical
matter is augmented by that of the convolutions, and com-
parative anatomy shows us that, in the animal kingdom,
intelligence increases with the extent of the convolutions.
Physiology again proves that in other parts of the nervous
system the white substance is simply conductive.f Ac-
cording to all indications, that of the brain has no other
function. " It is evident that here, as in all other parts
of the nervous system, the special activity belongs to the
* Longet, ii. 36. The above theory may be verified by the process of etheri-
sation. This process has two stages. In the first, the animal etherised (dog or
rabbit), loses its intelligence, its will, its instincts, and all its faculties with the
exception of its crude sensations. In this stage there is etherisation of the cere-
bral lobes and other parts of the encephalon, but not of the protuberance and
bulb. In the following stage the animal also loses its sensations. There is then
etherisation of the annular protuberance.
f Yulpian, 646, 669.
172 PHYSICAL CONDITIONS OF MENTAL EVENTS. [Boox IV.
grey substance. Pathological observations are equally con-
clusive Whilst lesions of the cerebellum, of the
optic thalaini. of the corpora striata, in fact of the white
medullary masses of the cerebral lobes, do not ordinarily
occasion any permanent or clearly marked disturbance of the
intellectual functions, extensive alterations of the grey sub-
stance of the convolutions, or morbid excitation of this sub-
stance, necessarily occasion weakening or exaltation of these
functions according to the nature of the alteration and
the stage at which it has arrived. Thus we can explain the
effects of diffused menin go- cephalitis and of simple menin-
gitis. The centre of cerebral activity being thus clearly
ascertained, it is not permissible to doubt that we have
here the true starting point of dementia and mania."
This grey cortical matter is composed of several layers,
which are alternately grey and white :* " We see in them
nuclei, and very many multipolar nervous cells of small
dimensions /' a quantity of fibres connect together different
regions of the grey layer of the same lobe, and those of one
lobe with the other ; other fibres connect the whole surface
of the grey matter with the corpora striata and optic thalami.
When transmitted by the fibres of the optic thalami and
corpora striata, the action, which in the corpora quadri-
gemina and annular protuberance had aroused a crude sen-
sation, passes on by the fibres of the white substance to the
cells of the cortical matter of the cerebrum, and propagates
itself, by the intermediary fibres, from one point to another
of the grey substance ; this action of the cortical cells is
the necessary and sufficient condition of images, and con-
sequently of all cognitions or ideas. The scalpel, the
microscope, and physiological observation can go no further
than this without falling into hypotheses; we can neither
define this action nor explain this propagation, and all we
know is that there is a molecular movement in the case.
But vivisections and the history of wounds of the head
here afford new evidence, which, combined with the former,
* According to M. Baillarger Vulpian, 644.
CHAP. I.] FUNCTIONS OF THE NERVOUS CENTRES. 173
enables us to gain a general view of the functions of the
brain. It is a repeating and multiplying organ, in which all
the different departments of the grey cortical matter fulfil
the same functions.
In the first place, " it is easy to prove by instances that
with an absence we may term complete of one cerebral
hemisphere, a man may still enjoy all his intellectual
faculties and even all his external senses This
was the case with one Vacquerie, in 18.21. He was hemi-
plegic on the left side, but his intellectual functions were
intact. At the autopsy, a quantity of serum was found
filling the place of the right hemisphere ; the cerebral sub-
stance on that side had disappeared."* Not only does one
hemisphere supply the place of the other, but any one
region of the brain, if sufficiently large, may supply the
place of another ; the proof of this lies in the fact that any
portion may be wanting without any of the mental faculties
being missed. f The disorganized or destroyed portion may
belong to the anterior or to the posterior lobes of the
brain ; it is of little consequence. " Berard reports a case
in which the two anterior lobes were crushed, while reason,
sensibility, and voluntary movements were retained." " An
officer had received a ball that had entered one temple
and passed out at the other ; the wounded man, who died
very suddenly three months afterwards, was observed till
then, and, during all that time, not only did he enjoy his
full intelligence, but showed unusual cheerfulness and
serenity in the intercourse of life."f After the battle of
Landrecies, " twelve men had received wounds at the top of
their heads, as large as the palm of the hand, with loss of
* Longet, "Anatomie and Physiologic du Systeme Nerveux," 666, 669. And
see Vulpian, 707. The same result is observed in pigeons when one hemisphere
has been removed. They preserve or regain all their faculties,
f Longet, ibid. Vulpian, 711.
J See "Bulletin de TAcademie de Medecine," x. 6, for an analogous case of a
child four years and a half old, through both of whose temples a ball had passed,
and who nevertheless lived twenty-six days, enjoying the whole of its intellectual
faculties, with complete memory, sound judgment, and with its character un-
affected by the injury.
174 PHYSICAL CONDITIONS OF MENTAL EVENTS. [BooK IV.
substance of integument, bone, dura mater, and brain.
These wounds were occasioned by horizontal sabre- cuts.
They had all travelled more than thirty leagues before their
wounds were dressed,, sometimes on foot, sometimes in
wretched cars, and went on favourably till the seventeenth
day. They preserved their appetite, their strength, and
even their martial appearance."* .... Such, again,
is the case of the dragoon mentioned by Lamotte, who
" had lost by a sabre-cut a piece of the right parietal bone
two inches long, and three or four inches of the left parietal
bone, down nearly to the ear. This wound, which com-
prised not only the membranes of the brain but the
longitudinal sinus and the brain itself, was followed by
syncope, consequent on the loss of blood, but gave rise to
no serious ill effects, f and was cured in two months and
a half. Lamotte is not the only one who has observed
cases of this kind, for they are not very uncommon."
All the mutilations practised on animals lead to the
same conclusion. " We may remove a considerable portion
of the cerebral lobes, either in front or behind, above or
below, without their functions being lost. A very small
portion, then, of these lobes is sufficient for the exercise of
their functions. In proportion as the removal goes on, all
the functions are weakened and gradually become extinct,
and, when certain limits are passed, they become actually
extinct Whenever one perception is lost, all are lost ;
whenever one faculty disappears, they all disappear
* Nelaton, "PathologieExterne," iii.572. Vidal, " Pathologic Externe,"ii. 744.
t Cf. Karl Vogt, "Legons sur 1'Homme," 127.
"If we gradually, layer by layer, remove the cerebral lobes in an animal, the
different phenomena of increasing stupidity become more and. more evident,
without our being able to determine a special action in any one direction. The
removal of half the brain seems to have no appreciable influence, which shows
that, for some time at least, the other entire half is able to supply the place of
the missing half. Still, we observe that the functions exhaust themselves more
quickly than when the brain is entire, which shows that the operation influences
the quantity, not the quality, of the manifestatioEs of the organ. Several ob-
servations have been collected of men who, after deep lateral wounds of the head,
followed by loss of cerebral substance, have experienced no diminution of their
faculties, but were speedily exhausted, and compelled, after short intellectual
labour, to stop and abandon themselves to complete repose or even to sleep"
CHAP. I.] FUNCTIONS OF THE NERVOUS CENTRES. 175
Provided the loss of substance occasioned to the cerebral
lobes does not exceed certain limits, these lobes regain after
a time the exercise of their functions ; when these first limits
are passed, the functions are but imperfectly recovered, and,
when the new limits are also passed, the functions are not
recovered at all. In short, as soon as one perception returns,
they all return, and as soon as one faculty reappears, they all
reappear/'* A frog, which had only a fragment left of its
posterior lobes, amounting to about an eighth of the whole
brain, had preserved the appearance of a healthy frog.
" Five weeks afterwards, a large fly, with one wing re-
moved, was put into its basin. As soon as the fly was
in the basin, the frog changed its attitude, and seemed to
watch the insect, and, as soon as it came near, made a
short jump and tried to catch it with its tongue ; but it
did not succeed the first time, and was obliged to recom-
mence the movement of projecting its tongue ; this time it
succeeded. On the following days, other flies were given
it, and it seized them at the first attempt. . . . The only
alteration observed in its movements was, that it was a little
less lively ; and again, it did not attempt, like other frogs,
to escape from the hand put out to catch it On
the contrary, when the brain is completely removed, there
is not the least attempt on the part of the frogs to take
flies which are given them ; and they do not even swallow
the flies till placed at the back of their mouths.'" We see
that in the case of the first frog the eighth part of its brain
supplied the place of the rest ; a larger portion would be re-
quired in the case of a superior animal, and, when we come
to the summit of the animal kingdom, the mutual dependence
of the different parts of the brain is much greater. But the
conclusion is still the same. The brain is a kind of poly pus,
whose elements have the same functions. We cannot say
with precision how many cells and fibres are required to
form one of these elements ; but each of these elements is
* Flourens, " Recherches Experimentales," &c., 99. Vulpian, 709 (Experi-
ments on Fowls and Pigeons).
176 PHYSICAL CONDITIONS OF MENTAL EVENTS. [BOOK IV.
capable, by its action, of giving rise to all normal images
and all their associations, and consequently to all the opera-
tions of the mind.
Having settled this, we can, by aid of psychology, take
a step in^ advance. We know that all ideas, all cognitions,
all the operations of the mind, are composed of associated
images, that all these associations depend on the property of
images to revive, and that images themselves are sensations
reviving spontaneously. All this agrees with the teaching
of physiology. An action is produced in the sensitive
centres strictly so called, protuberance, or corpora quadri-
gemina ; it there excites a primary or crude sensation. An
exactly similar action is consequently developed in a cortical
element of the cerebral lobes, and there excites a secondary
sensation or image. The first action is incapable, and the
second is capable of reviving spontaneously ; consequently
the crude sensation is incapable, and the image is capable
of reviving spontaneously. The more extensive is the cor-
tical matter of the brain, the more elements has it capable
of setting one another in action ; the more elements it
has capable of setting one another in action, the more deli-
cate an instrument of repetition it is. The brain, then, is
the repeater of the sensitive centres ; such is its office j
and it will the better fulfil this office the more numerous
the repeaters of which it is itself composed.
Here we perceive the mechanism which renders possible
the fundamental property of images I mean, their aptitude
for endurance and revival. As the brain is made up of
similar mutually-excitable elements, the action of the pro-
tuberance, of the corpora quadrigemina, and in general of
the centres of sensation, once repeated by one of its elements,
is transmitted in turn to the rest, and may thus revive inde-
finitely. Imagine a series of vibrating strings disposed in
such a way that the movement of the first is communicated
from string to string up to the last, and reverts from this
last to the first ; the illustration is homely but clear. Such
is the action which runs through the similar elements of
the brain ; and thus, in the absence of all external excita-
?HAP. L] FUNCTIONS OF TBE NERVOUS CENTRES. 177
tion, it lasts on, being effaced, reviving, and so persisting
indefinitely through a series of extinctions and revivals.
Such too is the image, and we have but to refer back to
its history to see it endure, become effaced, and reappear
in precisely the same manner. Assuming now that, by a
new excitation of the centres of sensation, a different action
is produced in one of the cerebral elements; according
to the law of communication/ it must pass in turn to the
other elements, and we shall have a different image which
will persist like the first, while becoming weaker and
stronger by turns. But the same cerebral element cannot be
in two different states at the same time, and consequently
cannot produce two different actions at the same time.
The cerebral elements, then, will be drawn in two different
directions, and, as the two actions are incompatible, one
alone will be propagated.
Which of them will be propagated ? There are conditions
which incline the balance to the one side or the other. Of
the two tendencies, one or the other will prevail.* We
have seen the laws which confer ascendancy on images and
deprive them of it, and these are precisely the ones which
determine the propagation of such or such a particular
action. Images strive together for predominance, and so
cerebral actions strive together for propagation. At any
given moment some one action will be propagated, and will
give the ascendancy to some image, and will then make
way for another action, which, propagated in its turn,
brings on the scene another image. Thus images succeed
one another, and become preponderant in proportion as the
action producing them is propagated through a greater
number of elements.
It must be observed that this presence of an image is
nothing more than its preponderance ; it is considerably
stronger than the others, that is all ; but it does not exclude
the others ; on the contrary, they still persist in a rudi-
* See ante, Book II. chap. ii. " Laws of the Revival and Obliteration of
Images."
N
)OK IV.
mentary and latent state ; and this obscure persistence may
be observed at any moment. You have sung over, some
fifteen or twenty times in succession, a new air which has
impressed you a great deal ; you are interrupted for some
little household occupation, or by some tiresome visit; on this,
another series of sensatiofas, images, and ideas unrolls itself
perforce within you ; but the first, though it has yielded its
place, has not been destroyed. It is pushed back, reduced ;
it permits the others to occupy the foremost place and to
obtrude themselves on the attention ; but though retired
and driven back into the distance and shade, it still exists.
You will find it there as soon as you revert to it ; it will
spring again to the light of its own accord as soon as the
intruders have gone. The evidence of its secret persistence
lies in the disturbance, the uneasiness, the dull tendencies
which you have felt all the time and which its obscure
presence excites in you. So again, you hear news, good or
bad, and after an hour you have ceased to think of it ; but
nevertheless, after the hour and perhaps for the whole day,
you still feel an ill- defined pleasure or inquietude which you
cannot explain at first sight, and which you do not under-
stand till you reflect, and the recollection of the news re-
turns. Among latent images or ideas, we must also reckon
those of all the actions we carry out while our minds are
occupied by some other preponderant image or idea. For
example, we follow out a thought as we walk along ; we
follow the tune of the piece we are playing, all the while
we are playing it ; we follow the argument of an author
while we are reading him aloud. In these different cases,
the images of the muscular movements we wish to accom-
plish must be present to our minds, since the muscular
movements are accomplished ; but their series is not observed
because another series is preponderant. This is the constant
state of our minds, a dominant image, in the full light, and
extended around it, a constellation of fading images, growing
more and more imperceptible ; beyond these, a milky way
of images wholly invisible, of which we have no other
consciousness than by the effect of their mass, that is to say,
CHAP. I.] FUNCTIONS OF THE NERVOUS CENTRES. 179
by our general feelings of gaiety or sadness. Every image
may pass through all the different states of light and dim-
ness ; at a certain limit, it escapes from consciousness, but
it is not therefore extinguished, and we do not know to
what degree of obliteration it may possibly descend. The
scale of these degrees descends to a marvellous depth; it is
enough, to convince oneself of this, to observe the revivals
of images* taking place after twenty, thirty, and fifty years'
interruption, and the abnormal reproductions of transient
experiences which seemed to have left no trace behind them.
We find here the same law as in the case of sensations
proper ; the image of which we are conscious is but a whole
whose elements may be infinitesimal.
Having determined this, we conceive the corresponding
cerebral process, and further, by this comparison, we
understand how there may be images within us of which
we have no consciousness. When an image is prepon-
derant, the action corresponding to it is propagated through
the greater part of the similar cerebral elements ; but
through the greater part only. Without this vortex are
other elements, in which a different action may be pro-
pagated at the same moment, whose whole intensity is less,
since the number of its factors is smaller ; to this action of
less intensity corresponds the accessory image, of less in-
tensity, all but invisible to consciousness, and which we
can only perceive indirectly, in the background. Let the
number of factors again diminish, the intensity of the action,
and, therefore, the intensity of the image will diminish pro-
portionately ; a moment will arrive at which the image will
be wholly without the range of consciousness, and never-
theless still capable of as many degrees of progressive weak-
ening as the number of its factors is capable of reductions.
The series of these degrees and of these reductions may be
enormous, and we can conceive that, in addition to secondary
and tertiary images, whose presence we may still distinguish
* " Laws of the Revival and Obliteration of Images." See for different in-
stauces ante, Book II. chap. ii. pp. 76, 77.
N2
130
PHYSICAL CONDITIONS OF MENTAL EVENTS. [Boos IV.
or divine, there are images again still more enfeebled,
below these, others still more so, and so on, till we come
to those aroused by the action of a single cerebral ele-
ment. Similarly we can conceive that the same image,
having been for a moment preponderant, may be effaced
by degrees, may subsist for a long time without our having
had consciousness of it, then, of a sudden, to our great
surprise, may reappear in full light, according to the more
or less extended ascendancy of the corresponding action,
which, propagated at first through the majority of the cere-
bral elements, becomes more and more limited, is con-
tracted and grows thinner, then, later on, reassumes the
ascendancy by the sudden appearance of some unforeseen
sensation which renews one of its fragments.
VII. We now know exactly the physical conditions of our
mental events ; the condition of our crude sensations* is a
certain action or molecular movement of the protuberance
of the corpora quadrigemina, and, in general, of some pri-
mary centre of the encephalon ; the condition of our images,
ideas, and the rest, is the same molecular movement repeated
and propagated in the elements of the grey cortical matter
of the brain. On this molecular movement depend the
events which we refer to our personality ; if the movement
exists, they exist ; if it is missing, they are missing. There
is no exception to this rule ; the loftiest thought, the most
abstract conception, is subject to it, through the words or
signs which serve as its foundation. Every idea, voluntary
or not, clear or obscure, complex or simple, fugitive or per-
sistent, implies a determinate molecular movement in the
cerebral cells. But, besides the mental events perceptible
to consciousness, the molecular movements of the nervous
centres also arouse mental events imperceptible to con-
sciousness. These are far more numerous than the
* Vulpian, 681. "It is a notion of extreme importance in physiology and
philosophy, that in every complete sensation there are two wholly distinct phe-
nomena, so distinct that they are seated in two different parts of the nervous system.
The one is the sensation strictly so called, and has as its seat the isthmus of the
'encephalon, and in part, the annular protuberance. The other is the intellectual
elaboration of the sensation, ani takes place in the brain properly so called."
CHAP. I.] FUNCTIONS OF THE NERVOUS CENTRES. 181
others, and of the world which makes up our being, we
only perceive the highest points, the lighted-up peaks of a
continent whose lower levels remain in the shade. Beneath
ordinary sensations are their components, that is to say,
the elementary sensations which must be combined into
groups to reach our consciousness. By the side of ordinary
images and ideas, are their collaterals, I mean the latent
images and ideas, which must take their turn of preponde-
rance and ascendancy in order to reach consciousness.
Having settled this, we see the moral world extending
far beyond the limits assigned to it. We are accustomed
to limit it to events of which we have consciousness ; but
it is now plain that the capacity of appearing to conscious-
ness belongs only to certain of these events ; the majority of
them do not possess it. Outside a little luminous circle, lies
a large ring of twilight, and beyond this an indefinite night ;
but the events of this twilight and this night are as real
as those within the luminous circle. Hence it follows that, if
we find elsewhere a nervous structure, excitations, reactions,
in short all the accompaniments and the physical indications
we meet with in the mental events of which we have con-
sciousness, we shall have a right here also to conclude the pre-
sence of moral events to which consciousness does not attain.
This is the case with reflex phenomena, one of the most
instructive instances physiology presents. There is in a
living body another centre besides the encephalon ; that is
the spinal marrow ; this marrow, like the encephalon, com-
prises a grey substance, which, like that of the encephalon,
is a terminus of transmitted excitations, and a starting-point
for reflected excitations. There is produced in it, as in the
encephalon, an unknown molecular movement, which is
excited by the action of the sensitive nerves, and excites
the action of the motor nerves, and which, according to all
analogies, arouses, like the molecular movement of the brain,
an event of the mental order. 1 In fact, the action it gives rise
to in the motor nerves is not irregular * " it is appropriate
* Vulpian, 414 et seq.
182 PHYSICAL CONDITIONS OF MENTAL EVENTS. [BOOK IV.
and adapted ;" it seems " intentional."" In every case, it tends
to an object, " even when the animal is deprived of its en-
cephalon," and this so perfectly, that many physiologists
have admitted a soul, or at least, " a perceptive and psychical
centre," in the segment of marrow thus cut off. " Here
is a Triton, whose head, with the anterior part of the body
and the two corresponding limbs, have been removed by a
transverse section. I pinch the skin of the lateral parts of
the body; there is, as you see, a movement of lateral curva-
ture of the body, producing a concavity of the irritated side,
and it is plain that the result of the movement is to remove
the irritated part away from the object irritating it. Now,
this is the precise movement which we see in unmutilated
Tritons when subjected to a similar irritation It
they do not succeed by this means, they attempt to rid
themselves of the irritating object by another plan which
this mutilated Triton will also put into execution. You see,
in fact, a movement takes place of the hind limb on the
irritated side." The movements alter according to the
point irritated, and the new combination of muscular move-
ments is always one adapted to avoid the new cause of
irritation. " All these movements are so well adapted and
natural, that, if the wound caused by the decapitation were
not apparent, you would think the animal had undergone no
mutilation, and the common character of these movements
is that their effect is defence against attacks from without."
So too, frogs when beheaded, can still leap and swim.
Further, " if we put a drop of acetic acid on the upper part
of the thigh of a decapitated frog, the hind limb bends in
such a way that the foot rubs against the irritated part."
The foot is amputated and the experiment repeated. " The
animal begins new movements to rub the irritated part ; but
he cannot reach it, and after some movements of agitation,
as if he were seeking a new mode of accomplishing his
design, he bends the other limb, and thus succeeds in doing
so." These are the most salient experiments, and it will be
comprehended that, to obtain such striking facts, we must
operate on the lower animals, whose life is more tenacious,
CHAP. I.] FUNCTIONS OF THE NERVOUS CENTRES. 187
and whose parts are less strictly connected with one another.
But similar ones are met with among the mammalia and
even in man.* Cases have been seen " of anencephalous
foetuses, who cried and sucked a finger placed to their
lips. Beyer, being compelled once to open the head of
a foetus to accomplish a delivery, and having completely
emptied the skull, saw the foetus, some minutes after birth,
give a cry, breathe, and move its hands and feet/' With
the higher animals, if we suppress the whole of the ence-
phalon that is to say, all the nervous centres with which
sensations and images, strictly so called, are connected
the spinal marrow and bulb, which alone remain, are still
capable, under the stimulus of the sensitive nerves, of ex-
citing and combining movements with some object in view,
as happens with the posterior limbs of a frog or Triton.
The animal still cries, though without pain, when its paw is
pinched ; it swallows food when placed at the end of its
gullet; it goes through all the movements of respiration.
In our own cases, sneezing, coughing, vomiting, are so
many systematically complex and useful movements, excited,
without exercise of will on our parts, through the medium
of the bulb.f In general, given in an animal a segment of
spinal marrow, with the sensitive nerves terminating in it,
and the motor nerves springing from it, when the sensitive
nerves are excited, the segment, commencing to act, will
set to work the motor nerves, and we shall see muscular
contractions. This may be readily observed in eels, sala-
manders, and serpents. LandryJ observed it in sucking
pigs, whose spinal marrow he divided into several segments,
while leaving the rest of the body intact. Animals thus
treated may live a long time, and, while the circulation
subsists, " the reflex excitability of a separated portion of
the marrow may persist almost indefinitely;" it has been
seen to last three months, and even for more than a year.
Every segment then is a sort of complete animal, capable
* Vulpian, 396. f Vulpian, 423.
% " Des Paralysies," 47. Experiments, 6, 7, 8. Vulpian, 432.
184 PHYSICAL CONDITIONS OF MENTAL EVENTS. [Boox IV.
in itself of being excited and of reacting, capable even of
living in an isolated state, if, as is the case with the in-
ferior animals, and notably with the annelid se, the mutual
dependence of the segments is not too great." 54 " We
should never come to an end if we attempted to enumerate
all the cases of reflex action. The majority of the muscular
movements of animal and of organic life, whether inter-
mittent or continuous, are accomplished by it alone, so that
we are obliged to consider all the central parts of the
nervous system, encephalon, bulb, spinal marrow, as con-
stantly set in action by the play of sensitive nerves, in such
a way as to excite the play of motor nerves, with an
accompaniment of sensations of which we are or are not
conscious. Whatever be the portion of the nervous
system observed, we never see in it any other than reflex
actions; they may be more or less complex, but are always
of the same kind. A white conducting cord conveys an
excitation to a central nucleus of grey substance ; a mole-
cular movement then arises in this substance, and thereupon
an excitation is carried on to the muscles by another white
conducting cord. These three movements so connected
constitute reflex action ; the grey substance, wherever it be,
in spinal marrow, protuberance, or cerebral lobes, always
acts in the same way.
Now, in the protuberance and the cerebral lobes, its
action arouses mental events, all of the same kind, tempo-
* Landry, "Paralysies," 47. The spinal marrow may be divided perpen-
dicularly to its axis in two, three, four, or more segments, without inducing any
modification of the phenomena in which it takes part. Each one of these parts,
anatomically constituted like the whole organ, possesses separately the same
faculties. I have shown by experiments 9, 7, and 8, that a simple transversal
section of the marrow, though it interrupts its continuity, leaves the reflex power,
the excitability of the nerves, the contractility and nutrition of the muscles, still
subsisting, in all the parts whose sensibility and movement are paralysed
Every segment of the marrow then is a real centre of inuervation Thus
we may consider the medullary cord as made up of a series of nervous centres
with identical properties, but affected nevertheless with different functions ac-
cording to the different organs with which the nerves springing from it are
connected This would be in accordance with comparative anatomy, which
shows that the marrow becomes gradually segmentary as we descend from the
mammalia to fish, and from these to animals still lower in the scale, to the
Crustacea or instance '
CHAP. L] FUNCTIONS OF THE NERVOUS CENTRES. 185
rary sensations or reviving sensations. We must, then,
admit that its action excites everywhere mental events of
an allied kind ; and inasmuch as, even in the protube-
rance and lobes, the greater part of these events are imper-
ceptible to consciousness, there is nothing to prevent its
action from arousing, in the marrow, mental events analogous
to sensation, but now situated, by nature not by accident,
beyond the reach of consciousness. We should thus have
three degrees in sensation. In the highest degree, in the
cerebral lobes, the sensation becomes capable of revival, and
is termed an image. In the next degree, in the protube-
rance, the sensation, incapable of revival, remains simply
crude. In the lowest degree, in the marrow, it is in a
still more incomplete state, and we cannot now define it
exactly from our having no consciousness of it, but we
recognise it correctly by this incapacity to appear, and it
probably resembles those elementary sensations which, when
separate, amount to nothing as far as consciousness is con-
cerned, and only make up an ordinary sensation by com-
bining with others to constitute a whole. So too there
would be three degrees of complication in the action of the
nervous centres. At the lowest degree, in the marrow,
would arise fragmentary actions analogous perhaps to
those which excite elementary sensations, imperceptible to
consciousness. In the next degree, in the protuberance,
these same actions combine, when transmitted, into a total
action exciting the ordinary total sensation. In the highest
degree, in the lobes, this total action, transmitted a
second time, is repeated indefinitely by a series of mutually
excitable cerebral elements, and then excites those secondary
and reviving sensations we term images. We thus conceive,
for the action of the nervous centres as for mental events,
three stages of successive transmission and elaboration, and
we can thus include in a general view the reciprocal depen-
dence and the development of the two streams.
They form two long series, the one of which is the
necessary and sufficient condition of the other, and which
correspond as precisely as the convexity and concavity of
186 PHYSICAL CONDITIONS OF MENTAL EVENTS. [BOOK IV.
the same curve. On the one side are the molecular
movements of the nervous centres ; on the other are mental
events,, all more or less analogous to sensation. The first
invariably excite the second, and the degree of complication
found in the one series always corresponds to an equal degree
of complication in the other. At a certain degree, the second
series may be known by a special inward process we term
consciousness ; but, even when at this degree, it generally
happens that the events of this series are not thus known.
Beneath those which consciousness attains, there are many
others to which it cannot attain, and which we are compelled
to conceive on the type of those we know, but on a reduced
and fragmentary type, and becoming more reduced and frag-
mentary as the nervous action exciting them becomes more
simple. Thus we see that, beneath the ordinary sensations
which we know by consciousness, there descends an indefinite
series of analogous mental events, more and more imperfect,
more and more removed from consciousness, without our
being able to put a limit to this series of increasing degra-
dations ; and this successive lowering, which has its coun-
terpart in the attenuation of the nervous system, leads us
to the foot of the zoological scale, while connecting together,
by a continuous sequence of intermediate links, the most
rudimentary outlines and highest combinations of the nervous
system and the mental world.
CHAP. II.] THE NERVOUS CENTRES AND THOUGHT. 187
CHAPTER II.
RELATIONS OF THE FUNCTIONS OF THE NERVOUS CENTRES AND
MENTAL EVENTS.
I. HERE we have the great question of the physical and
the moral world,, two worlds which the most obvious expe-
rience shows to be inseparably connected together, and which
their representations show us as absolutely irreducible to
one another. On the one hand, we prove that the second
depends on the first; on the other hand, we are unable to
conceive that it so depends. Physiologists, on the one
hand, willingly lose sight of the second fact, and tell us
that " mental events are a function of the nervous
centres, just as muscular contraction is a function of the
muscles, and the secretion of bile, a function of the liver/'
Philosophers, on the other hand, willingly lose sight of the
first fact, and tell us that " mental events have nothing in
common with the molecular movements of the nervous
centres, and appertain to a being of different nature." On
this, cautious lookers-on interpose and conclude that: "It is
true that mental events and the molecular movements of the
nervous centres are inseparably connected together; it is
true that as far as our mind and powers of conception are
concerned they are absolutely irreducible to one another.
We stop at this difficulty, and will not even attempt to
surmount it; let us content ourselves with ignorance." For
our own parts, if we attempt to make an advance into this
obscurity, it is because we have already made several ad-
vances. On the one hand, we have seen that our most
abstract ideas, being signs, are reduced to images, that our
images themselves are reviving sensations, that consequently
our whole entire thought is reduced to sensations. The
difficulty then is simplified, and it is now a question only of
188 PHYSICAL CONDITIONS OF MENTAL EVENTS. [BooK IV.
comprehending the connexion between a molecular move-
r ment and a sensation. On the other hand, we have seen that
sensations, though apparently simple, are wholes ; that these
wholes, though apparently irreducible to one another, may
be composed of similar elements ; that at a certain degree
of simplicity these elements are no longer perceived by
consciousness ; that the sensation is then a compound of
rudimentary events, capable of indefinite degradations, in-
capable of coming within the grasp of consciousness, but
whose presence, and further, whose effectiveness is proved by
reflex actions. The difficulty is thus simplified a second
time ; it is A now a question only of comprehending the con-
nexion between these events and a molecular movement.
The obscurity still remains very great ; for we can never con-
ceive these events otherwise than after the type of ordinary
sensations, and between this conception and that of a move-
ment, is still a gulf. But we know that ordinary sen-
sation is a compound, that it differs from its elements, that
these elements escape our consciousness, that they are none
the less real and active, and, in this deep lower twilight
whence the sensation arises, we shall perhaps discover the
link between the physical and the moral world.
II. Let us begin by stating the difficulty in all its force.
Since mental events are nothing more than sensations
more or less twisted and transformed, let us compare a sen-
sation with a molecular movement of the nervous centres.
Let us take the sensation of golden yellow, that of a musi-
cal note like ut, that given by the emanations of a lily, by
the taste of sugar, by the pain of a cut, by tickling, by
heat or cold. The necessary and sufficient condition of
such a sensation, is an internal movement in the grey
substance of the protuberance of the corpora quadrigemina,
in short, of a centre of sensation ; this movement may be
unknown, it matters little ; whatever it may be, it consists of
a more or less complex and extensive displacement of mole-
cules, and is nothing more. Now, what relationship can
we imagine between this displacement and a sensation?
Cells, constituted of a membrane and one or more nuclei,
CHAP. II.] THE NERVOUS CENTRES AND THOUGHT. 189
are strewed in a granulated substance, a kind of flabby
pulp or greyish jelly, made up of nuclei and of innume-
rable fibres ; these cells ramify into slender prolongations,
which probably connect themselves with the nervous fibres,
and it is supposed that they thereby communicate with one
another, and with the white conductive parts. Study as
closely as you will the anatomical preparations and mi-
crographic plates which show us this apparatus; suppose
the power of the microscope indefinitely increased, and the
enlargement carried to a million or a thousand million
diameters. Suppose physiology at maturity, and the theory
of cellular movements as far advanced as the physical
theory of undulations ; suppose we knew the mechanism of
the movement produced in the grey substance during a
sensation, its circuit from cell to cell, its differences accord-
ing as it excites a sensation of sound or of smell, the link
connecting it with movements of heat or electricity, and
further, the mechanical formula which represents the mass,
velocity, and position of all the elements of the fibres and
the cells at any time of their movement. We should
even then have movement only, and movement, of what-
ever kind it be, rotatory, undulatory, or what else, has no
resemblance at all to a sensation of bitter, of yellow, of
cold, or of pain. We cannot convert either of these two
conceptions into the other, and consequently the two events
seem to be of absolutely different quality; so that analysis,
instead of filling up the interval between them, seems to
enlarge it to an infinite extent.*
* Cf. the following extract from Professor Tyndall's Address to the British
Association for the Advancement of Science, on " The Physical Forces and
Thought."
" I can hardly imagine that any profound scientific thinker, who has reflected
upon the subject, exists who would not admit the extreme probability of the
hypothesis, that for every fact of consciousness, whether in the domain of sense,
of thought, or of emotion, a certain definite molecular condition is set up in the
brain ; that this relation of physics to consciousness is invariable, so that, given
the state of the brain, the corresponding thought or feeling might be inferred ; or
given the thought or feeling, the corresponding state of the brain might be 'in-
ferred. But how inferred ? It is at bottom not a case of logical inference at all,
but of empirical association. You may reply that many of the inferences of
science are of this character ; the inference, for erample, that an electric current
190 PHYSICAL CONDITIONS OF MENTAL EVENTS. [Boo* IV.
III. Repulsed in this direction, we must turn to another.
It is true that we cannot conceive the two events other-
wise than as irreducible to one another ; but that may
depend on the way in which we conceive them and not
on their actual qualities ; their incompatibility is perhaps
rather apparent than real ; it arises on our side and not
on theirs. There would be nothing extraordinary in such
an illusion as this. As a general rule it is sufficient for
a fact to be known to us in two different ways, for us to
conceive, in its place, two different facts.
Such is the case with the objects we know by the senses.
A person born blind* who has just been couched, remains
for a considerable time unable to reconcile his perceptions
of touch with those of sight. Before the operation, he re-
presented to himself a china cup as cold, polished, and
capable of affording to the hand certain sensations of re-
sistance, weight, and form ; when he sees it for the first
time, and it gives him the sensation of a white patch,
he conceives the white lustrous object as something dif-
ferent from the resisting, heavy, cold, polished object. He
would stop at this, if he did not acquire new experiences ;
of a given direction will deflect a magnetic needle in a definite way ; but the
cases differ in this, that the passage from the current to the needle, if not de-
monstrable, is thinkable, and that we entertain no doubt as to the final mechanical
solution of the problem ; but the passage from the physics of the brain to the
corresponding facts of consciousness is unthinkable. Granted that a definite
thought, and a definite molecular action in the brain occur simultaneously ; we
do not possess the intellectual organ, nor apparently any rudiment of the organ,
which would enable us to pass by a process of reasoning from the one phenomenon
to the other. They appear together, but we do not know why. Were our minds
and senses so expanded, strengthened, and illuminated as to enable us to see and
feel the very molecules of the brain ; were we capable of following all their
motions, all their groupings, all their electric discharges, if such there be ; and
were we intimately acquainted with the corresponding states of thought and
feeling, we should be--as far as ever from the solution of the problem, ' How are
these physical processes connected with the facts of consciousness ? ' The chasm
between the two classes of phenomena would still remain intellectually impass-
able. Let the consciousness of love, for example, be associated with a right-
handed spiral motion of the molecules of the brain, and the consciousness of hate
with a left-handed spiral motion. We should then know when we love that the
motion is in one direction, and when we hate that the motion is in the other ;
but the 'WHY?' would still remain unanswered." See Report xxxviii. for
the year 1868. Transactions of the Sections, p. 5.
* See post, Part II. book ii. chap. ii.
CHAP. II.] THE NERVOUS CENTRES AND THOUGHT. 191
the two things would always be different in quality; they
would form two worlds, between which there would be no
communication. And so, if your eyes are shut and you
are not aware of what is going to happen, and you see a
flash, then hear a sound, and then feel as if hit on the arm
with a stick (the experiment may be tried on a child or an
ignorant person), you will imagine that you have been
struck, that some one has whistled, and that a bright light
has shone into the room ; and yet the three different facts
are but one, the passage of a current of electricity. The
science of acoustics had to be constructed to show that the
event which arouses in us, through the tactile nerves,
sensations of vibration and tickling, is the same as that
which, through the acoustic nerves, gives rise to sensations
of sound. Till very recently " phenomena of heat,* elec-
tricity, light, ill- denned enough in themselves, were thought
to be produced by so many peculiar agents, fluids pos-
sessed of special activities. A closer examination has
enabled us to recognise that this conception of different
specific heterogeneous elements has for foundation one
single reason namely, that the perception of these different
orders of phenomena takes effect in general through dif-
ferent organs, and by thus attaching themselves more spe-
cially to some one of our senses, they necessarily excite
special sensations. The apparent heterogeneity then would
be not so much in the nature of the physical agent as in
the functions of the physiological instrument by which the
sensations are effected; so that by transferring, by an
erroneous attribution, these differences of appearance from
the effect to the cause, we should in reality have classified
the intermediate phenomena by which we have cognizance
of the modifications of matter, rather than the very essence
of these modifications All physical phenomena,
whatever be their nature, seem to be at foundation nothing
more than the manifestations of one and the same pri-
* M. de Senarraont. From a Lecture at the Ecole Polytechnique, cited by
Saigey. " La Physique Moderne," p. 216.
192 PHYSICAL CONDITIONS OF MENTAL EVENTS. [Boos IV.
mordial agent/' Tims, the conception we form bears in-
variably a deep imprint of the process forming it. We are
compelled then to take count of this imprint ; and there-
fore, when we find within us two ideas which have entered
by different routes, we ought to mistrust the tendency
which induces us to assert a difference, and above all an
absolute difference, between their objects.
Now when we examine closely the idea of a sensation
and the idea of a molecular movement of the nervous
centres, we find that they enter by routes not merely dif-
ferent, but contrary. The first comes from within, without
any intermediate ; the second comes from without, through
several intermediates. To represent to oneself a sensation
is to have present an image of that sensation, that is to say,
the sensation itself directly repeated and spontaneously
reviving. To represent a molecular movement of the
nervous centres is to have present images of the tactile,
visual, and other sensations, which it would excite in us if it
were acting on our senses from without, that is to say, to
imagine sensations of white, of grey, of flabby consistency,
of cellular or fibrous form, of small quivering points, that
is, in fact, if we go further, to combine internally the names
of movement, velocity, and mass, which denote collections
and extracts of muscular and tactile sensations. On the
whole, the first representation is equivalent to its object, the
second to the group of sensations which its object would
excite in us. Now we cannot conceive more dissimilar
processes of formation. In the case, just now, of different
senses, the two representations reached us by two different
roads, but both were external, so that there was nothing to
prevent their having some common starting-point. Here,
the two representations reach us by two opposite roads, one
from within, the other from without, in such a way that
these roads are perpetually divergent, and that we are un-
able to conceive their having the same starting-point. Thus
the fundamental opposition of the two processes of forma-
tion is sufficient to explain the mutual irreducibility of the
two representations. One and the same single event known
CHAP, II.] THE NERVOUS CENTRES AND THOUGHT. 13
in these two ways will appear double, and, whatever be the
link which experience establishes between its two manifes-
tations, we shall never be able to convert one of them into
the other. According as its representation comes from with-
out or within, it will invariably appear as a thing without, or
a thing within, and we shall never be able to reduce that
which is without to that which is within, or that which is
within to that which is without.
IV. It is possible then that the sensation and the internal
movement of the nervous centres may be at bottom one and
the same unique event, condemned, by the two ways in
which it is known, always and irremediably to appear double.
Another line of reasoning leads to a similar conclusion. In
fact, we have seen that our sensations are but wholes, com-
posed of elementary sensations, that these are similarly
composed, and so on; that at each of these degrees of
composition the compound presents itself to us with qualities
wholly different from those of its elements, that consequently,
the more simple the elements, and the more removed from
the grasp of consciousness, the more must they differ, as far
as we are concerned, from the whole which is accessible to
consciousness, in such a way that the aspect of the infini-
tesimal elements at the foot of the scale, and that of the
whole sensation at the summit of the scale, must be wholly
and entirely different. Now such is the aspect of the
molecular movements when compared with that of the
entire sensation. Consequently, there is nothing to prevent
the molecular movements from being the infinitesimal ele-
ments of the whole sensation. Thus, the fundamental objec-
tion is removed. If our conceptions of the mental and of the
cerebral event are irreducible to one another, it may doubt-
less depend on the two events being, in fact, irreducible to
one another; but it may also depend, first, on the event
which is single, being known to us in two directly con-
trary ways, and, next, on the mental event and its ultimate
elements being forcedly presented to us under absolutely
opposite aspects.
There is room then, and equal room, for the two hypo-
o
194 PHYSICAL CONDITIONS OF MENTAL EVENTS. [Boox IV.
theses, for that of two heterogeneous events, and for that
of one and the same event known under two different
aspects. Which must we choose? If we adopt the first
we are confronted with a link, not only unexplained, but
inexplicable. For, the two events being by nature irre-
ducible to one another, form two worlds, apart and isolated;
we exclude by hypothesis any more general event of which
they might be but distinct forms and particular cases ; we
declare beforehand that their nature furnishes nothing on
which their reciprocal dependence may be founded, We
are compelled, then, in order to explain this dependence, to
seek for it in something above their nature, and therefore
above all nature, for they, between them, make up all nature,
consequently, then, in the supernatural. So that we must
call in aid a miracle, the intervention of a superior being.
The philosophers of the seventeenth century, Leibnitz and
Malebranche at their head, clearly saw this consequence,
and boldly decided that there was a pre-established harmony,
the artificial agreement of two independent clocks, an ex-
trinsic adjustment descending from on high, a special
decree of God. Nothing could be less conformable to the
methods of scientific induction : which exclude all hypotheses
by which is nothing explained. We are driven back then to
the second supposition. And, first, it is in itself as plausible
as the other. Again, it has analogies and numerous pre-
cedents in its favour ; for, like so many other physical, and
psychological theories, it takes into consideration the in-
fluence of the percipient and sentient subject, the structure
of the observing instrument, the effects of optics. Besides
this, it calls in no third cause, no imaginary or unknown
property ; it is as little hypothetical as possible. Finally, it
shows not only that the two events may be connected with
one another, but that they must always and necessarily be
so connected. For, from the moment they are reduced to
one single fact, possessed of two aspects, they evidently
become like the front and reverse side of a surface,
so that the presence or absence of the one will infallibly
result in the presence or absence of the other. We are
CHAP. II.] THE NERVOUS CENTRES AND THOUGHT. 195
entitled then to admit that the cerebral event and the
mental event are, at foundation, but one and the same event
under two aspects, one moral, the other physical, one ac-
cessible to consciousness, the other accessible to the senses.
Now of the two ways in which we attain to this event, the
one, consciousness, is direct : to know a sensation by con-
sciousness, is to ha 
