Witi equal clearness does Mind display the further trait THE COMPOSITION OF KlXD. 1(SQ of Evolution — increase of definiteness. Both, the central! r- initiated feelings and the internal peripherally-initiated feel- ings,, which play so secondary a part in what we understand as Mind, we found to be very vague — very imperfectly limited by one another. Contrariwise, it was shown that the mutual limitations are decided among those peripherally- initiated feelings which, arising on the outer surface, enter largely into our intellectual operations; and that the visual feelings, which enter by far the most largely into our in- tellectual operations, are not only by far the sharpest in their mutual limitations, but form aggregates that are much more definitely circumscribed than any others, and aggregates between which there exist relations much more definite than those entered into by other aggregates.
Thus the conformity is complete. Mind rises to what are j universally recognized as its higher developments, in pro- J portion as it manifests the traits characterizing Evolution in! general (First Principles, §§ 98. — 145). A confused| sentiency, formed of recurrent pulses of feeling having bur. little variety of kind and but little combination, we may conceive as the nascent Mind possessed by those low types in which nerves and nerve-centres are not yet clearly differentiated from one another, or from the tissues in which they lie. At a stage above this, while yet the organs of the higher senses are rudimentary, and such nerves as exist are incompletely insulated, Mind is present probably under the form of a few, sensations, which, like those yielded by our own viscera, are simple, vague, and incoherent. And from this upwards, the mental evolution exhibits a differentia- tion of these simple feelings into the more numerous kinds which the special senses yield -3 an ever-increasing integra- tion of such more varied feelings with one another and with feelings of other kinds; an ever-increasing multiformity in the aggregates of feelings produced; and an ever-increasing distinctness of structure in such aggregates. Thatjs^to say, | 190 THE INDUCTIONS OF PSYCHOLOGY.
I parallel to tliat redistribution of matter and motion which constitutes Evolution as objectively displayed.
§ 76. The correspondences between these views of mental composition and the general truths respecting nervous structure and nervous functions set forth in the last part, must be briefly indicated.
Speaking generally, feelings and the relations between feelings, correspond to nerve-corpuscles and the fibres which connect nerve-corpuscles; or rather, to the molecular changes of which nerve-corpuscles are the seats, and the molecular changes transmitted through fibres. The psychical relation between two feelings, answers to the physical relation between two disturbed portions of grey matter, which are put in such direct or indirect communication that some discharge takes place between them.
The fact that, as elements of consciousness, the relations between feelings are very short in comparison with the feel- ings they unite, has thus its physiological equivalent in the fact that the transmission of a wave of change through a nerve-fibre, is very rapid in comparison with the transforma- tion it sets up in a nerve-centre. If we consider each such transformation to be physically that which psychically we consider a unit of feeling, then, remembering its appreciable duration, we may understand how it happens that when the waves of molecular change brought by an in-coming nerve- fibre exceed a certain rate of recurrence, the transformation set up by each lasts till the nest commences; and hence the corresponding units of feeling become fused into a con- tinuous feeling or sensation.
We have seen that predominance of the relational element of Mind, characterizes the peripherally-initiated tracts of consciousness which external objects produce. Between this fact and the facts of nervous structure, there is an obvious agreement. Take the case of the eye. The retina being an area formed of an immense number of sensitive elements, close to, but separate from, one another, and having each THE COMPOSITION OP MIND. 101 an independent centripetal fibre; it results that the rela- tions that may 'be established between each one and all tie others are enormons in number, and that enormous numbers of relations may be established between simultaneously- excited clusters of them and other simultaneously-excited clusters. The sharpnass of mutual limitation of the feelings and clusters of feelings here initiated, is also clearly due to these same structural peculiarities; as are also their rigid cohesions and extensive integrations. Without naming the intermediate cases, it will suffice if we pass to the other extreme and observe how, in the visceral nervous system, whence conie feelings that are so simple, so indefinite, and so incoherent, there is an absence of the appliances which secure independent excitements of adjacent nerve- terminations.
A further harmony of the same order may be noted. The relational element of Mind, as shown in mutual limitation, in strength of cohesion, and in degree of clustering, is greater between feelings of the same order than between feelings of one order and those of another. This answers to the fact that the bundles of nerve -fibres and clusters of nerve- vesicles belonging to feelings of one order, are combined together more directly and intimately than they are with the fibres and vesicles belonging to feelings of other orders. Similarly, it holds among feelings of different orders, that the readiness to enter into relations is much greater between those arising in the higher sense-organs, which have nervous centres closely connected, than between them and the visceral feelings which arise in parts of the nervous system that communicate but indirectly with the higher centres. Even an anomaly appears thus explicable. That such unrelational feelings as smells have exceptional powers of calling up remembrances of past scenes, is probably due to the fa,ct that the olfactory centres are outgrowths from the cerebral hemispheres.
. We have seen that the development of Mind is funda- mentally an increasing integration of feelings on successively- 100 THE INDUCTIONS OF PSYCHOLOGY.
higher stages, along with which there go increasing hetero- geneity and definitenessj and these traits answer to traits in the evolution of the nervous system before contemplated. For we found that along with growing distinctness and mulrlfbrmirv of structure, there is throughout an advancing integration of structure as well as of mass. (See § 8.) One- more correspondence of moment may be pointed out a correspondence that replaces a supposed discordance.
The most developed and conspicuous part of Mind chiefly occupies men's attention; and hence they speak of Mind and Intelligence as equivalents. As hinted in § 7, even physiologists, intending to ignore all pre-coneeptions, have been led" into difficulties of interpretation by inadvertently setting- out with this belief as their postulate. But Mind is not wholly or even mainly. Intelligence. We have seen that it consists largely, and in one sense entirely, of Feelings. Not only do Feelings constitute the inferior tracts of conscious- ness, bat Feeling's are in all cases the materials out of which, in the superior tracts of consciousness,: Intellect is evolved by structural combination. Everywhere Feeling is the substance of wtdch, where it is present, Intellect is the form. And where Intellect is not present, or but little present, Mind consists of feelings that are unformed or but little formed. Intellect comprehends only the relational elements of Mind; and to omit Feelings is to omit the terms between which, the relations exist. The recognition of this truth saves us from the error of looking for a regular correspondence between the development o£ the nervous system and the degree of Intelligence. As in § 7 we saw that the size of the nervous system varies partly as the quantity of motion evolved, and partly as the complexity of that motion; so here we see that the size of the nervous system varies partly as the quantity of Feeling (which has a general relation to the quantity of motion) and partly as the degree of Intellect (which has a general relation to the complexity of the motion). And thus interpreting the facts, supposed anomalies disappear* CHAPTER ILL THE RELATIVITY OF FEELINGS.
§ 77. Mind being composed of Feelings and the Rela- tions between Feelings, and the aptitudes of Feelings for entering into Relations varying with their- kinds, the..Relati- vity of Feelings is an expression applicable, in one sense,, to certain, of the purely subjective phenomena described in the last chapter. But it is" 'here, to be understood in quite a different sense. Having "contemplated Feelings in their relations to one another as components of consciousness, we have now to contemplate them inr their relations to th.e la- things beyond consciousness by which they are produced. ' "" Moreover, the things beyond consciousness here to be considered, are not the nerve- disturbances which are the physical sides of what we call feelings on their psychical sides: already, in the chapter on.2Estho -Physiology,, the relations between the subjective and objective faces of nervous changes have been described. Our present inquiryf is into the nature of the connexions between feelings, and( forces existing outside the organism. To treat of thesef without going over any ground before traversed is difficult; since an external action being related to a feeling only through an intermediate nervous change, the intermediation cannot well be left out of sight. Occasional brief repetitions must therefore be excused.
It should be further premised that we are here concerned o 194 THE INDUCTIONS OF PSYCHOLOGY.
mainly with peripherally-initiated feelings •which Lave exter- nal origins; or rather,, with those primary or vivid forms of them, which we call real, in contradistinction, to the secondary or faint forms we call ideal.
§ 78. The general truth,, familiar to all students of Psy- chology^ which it is the object of this chapter to present under its many aspects, is that though internal feeling habitually depends on external agent, yet there is no likeness I bet ween them either in kind or degree. The connexion ] bet ween objective cause and subjective effect is conditioned jin ways extremely complex and variable — ways which we will proceed to consider seriatim.
We shall find that each set of conditions so modifies the connexion between objective cause and subjective effect as to determine the qualitative character of the effect. In • other words, the^ saine agent produces feelings of quite i unlike natures according to the circumstances under which •:it_acts, j \ We shall further see that, besides this qualitative unlike- ness, there. is a quantitative unlikeness. Between the outer force and the inner fe'eling it excites, there is no such cor- relation as that which the physicist calls equivalence — nay, the two do not even maintain an unvarying proportion. Equal amounts of the same force arouse different amounts of the same feeling, if the circumstances differ. Only.while all the conditions remain constant is there something like a constant ratio between the physical antecedent and the psychical consequent.
§ 79. Were I not bound to enumerate all aspects of this relativity, it would be needless to say that the connexion between the outer agent and the inner feeling generated by it, depends on the structjire^ ObviousIyTEe forms o? sensation that can be roused in the consciousness of a creature, are primarily determined by THE RELATIVITY OF FEELINGS.
the peripheral organs with wMcli its type is endowed. This is so even with the most general of the sensations — that of Touch. A Crustacean, everywhere enclosed in a hard exo- skeleton, can have no such tactual impressions as those which are possible to a soft-skinned animal. The impressions received from the ends of its limbs and claws when they come in contact with external objects, may be compared to those which a man receives from poking objects with the end of his walking-stick. Still more manifestly are the special sensations dependent for their qualities on the presence of special sense-organs. Take the auditory sensations. Various aquatic creatures that have no developed organs of Hearing, are nevertheless affected by those vibra- tions which to creatures better endowed are sonorous. When such vibrations are propagated through their medium, they contract themselves, or they withdraw into their shells if they have them. We may reasonably assume that what they feel is a jar somewhat resembling the jar received by the hand from a vibrating musical instrument. But in any case, the quality of the feeling excited in these lower animals by sonorous waves, is wholly unlike the quality of the feel- ing which such waves excite in higher animals.
That, qualities being alike, the quantities of the feelings produced by given agents vary with the specific structures, is an equally familiar truth. In a bird or mammal having eyes that fit it for nocturnal habits, the sensation aroused by a faint light, is much greater than is aroused by it in a diurnal bird or mammal; and the light which gives to a diurnal creature a moderate amount of sensation suffices to dazzle the nocturnal creature by its excess. Similarly \vith the olfactory feelings. An odour which has no ap- preciable efect on the consciousness of a man, has a very marked effect on the consciousness of a dog. Even varieties of dogs, as the greyhound and the beagle, yield us evidence of decided quantitative differences between the mental changes caused by the same odour. • 196 THE INDUCTIONS OP PSYCHOLOGY.
These few instances warrant us In suspecting that; in.no two species does a given amount of a given outer agent (excite exactly the same kind and quantity of feeling.
§ SO. This apparently hasty generalization is justified by the generalization to which we come next; namely., that within the same species the relation bet ween objective cause and subjective effect varies both qualitatively and quantita- tively with the constitution — varies, that is, with the individual structure.
I That peculiarity of vision discovered in himself by Dalton, and sometimes named after him,, yields an instance of {qualitative difference. To those organized as he was,, the 'visible world does not present all the various feelings of colour that it does to mankind in general. Sensations which to others seem strongly contrasted, as red and green, seem to them the same. Whence we must conclude that certain etherial undulations produce in such persons feelings unlike those they produce in other persons. From sentient states excited through the ears, inav be drawn another illustration. Aerial pulses recurring at the rate of sixteen per second are perceived by some as separate pulses; but by some they are perceived as a tone of very low pitch. Similarly at the other extreme. Vibrations exceeding thirty thousand per second, are inaudible through certain ears; while through ears that are, as we may suppose, of somewhat unlike structures, these rapid vibrations are known as an excessively acute sound.
> Quantitative differences of sensation that are caused by dif- ferences of individual organization, every one observes. All orders of sensations exemplify them. Here are instances from each. Thick-skinned persons are insensible to tactual impressions which thin-skinned persons clearly feel; and there are persons by whom minute unlikenesses of sur- face are so distinctly perceived that they are employed to judge of commodities, such as raw silk, by handling THE RELATIVITY OF FEELINGS. 19?
them. How amounts of Savour qnite inappreciable by some are readily appreciable by others, the dinner-table constantly reminds ns. And that there are professional tasters, shows that the gustatory feeling produced by a given quantity of sapid substance, is, in exceptional organizations, much greater than usual. With smells it is the same. There are those to whom quite delicate perfumes seem of overpowering strength. And there are those to whom odours usually felt to be disgusting in the extreme, are scarcely perceptible. Constitutional differences in quickness of hearing, sometimes marked between persons of the same race, are more marked between persons of different races. By putting his ear to the ground a savage hears sounds inaudible by a civilized man. The; like holds with visual sensitiveness. The Bushman is im- pressible by changes in the field of view which do not impress the European. And such tests as occur in the telescopic search for minute stars, show that, in the same race, the amount of light which excites a distinct feeling in one person, excites no feeling in another.
Thus we may make wider the startling inference drawn in the last section. Besides concluding that in no two species are the subjective effects produced by given objec- tive actions absolutely alike, qualitatively and quantitatively; we may conclude that they are absolutely alike in no two, individuals of the same species.
, § 81. Whatever there may seem of excess in this state-j rnent will disappear when we remember that even^jin. the| same individual the quantity, if not the quality, of the feel| "ing excited by an external agent constant in kind and del gree, varies according to the constitutional staie/<>v '•>• - '< T Of qualitative variations we have but vague and indirect evidence. Still the experiences of invalids yield reason to suspect that they occur. There are abnormal states of the nervous system during which illusive sedations trouble the 198 THE INDUCTIONS OF PSYCHOLOGY.
patient. The consciousness of a disagreeable smell which is one of the premonitory symptoms of an epileptic fit, may be named as an instance. And if feelings of purely subjective origin, so strong as to "be mistaken for feelings of objective origin, may arise from extreme nervous derangements, it is reasonably inferable that smaller nervous derangements will often arouse vague subjective states which may mingle with, and qualify, the feelings objectively originated.
The quantitative variations which variations of constitu- tional state entail among the feelings produced by equal external agents, are very familiar. As before, some are con- sequent on derangements of health and some on advancing years. In certain conditions of nervous irritability, sounds of ordinary strength seem intolerably loudj daylight becomes unbearable from the excess of visual feel- ing it causes; and even the skin becomes unduly sensitive: there is what is called hyper-sesthesia. Contrariwise, there are deviations from health characterized by an anaesthesia allied to that artificially caused — a state of comparative indifference to amounts of external stimuli which commonly arouse much feeling. ', How along with decline of vigour in old age there goes an increasing anaesthesia of one or more kinds, we.have daily proof. There is dimness of sight; there is dulness of hearing; there is often obtuse- ness of taste.
Thus, besides seeing that the subjective effect produced by each objective cause varies with the structure of the species, and varies with the structure of the individual of the species, we see that it varies with the constitutional state of the individual— often in a marked degree. Very ^possibly the ratio is never twice the same; but always differs infinitesimaliy, if not appreciably.
§ 82. The kind and degree of effect which an external ; physical stimulus produces on the psychical state, djepends ; also on the part of the organism subject to it. Equal quan- . THE EELATIVITY OF PEEL&NGS. 199 titles of tlie same force excite feelings widely unlike, quali- tatively and quantitatively, according to the structures of the peripheral organs on which they fall.
The qualitative differences we recognize so much as matters of course that we forget their! significance. Here, however, they must not be passed over. Many kinds of matter which, when applied i'o the skin at large, cause only sensations of touch, cause, -when applied to the tongue, sensations of touch and taste; ^or, if they are kinds of matter having the tastes we call pu:agent, they arouse in the skin sensations of heat or tingling.! Similarly with volatile substances. A whiff.of;, ammonia coming in contact with the eyes^ produces a sma-:rt; getting into the nostrils, excites the consciousness we describe as an intolera- bly strong odour; being condensed on the tongue, generates an acrid taste; while ammonia applied iln solution to a tender part of the skin, makes it burn, as we say. The - feeling caused by sonorous undulations;, already adverted to as varying with the structure of the species, must be named here also as varying with the structure of the part affected. A vibrating tuning-fork touched T^ith the fingers, gives them a sense of jar; held between t'h'e teeth, it gives this same sense to the parts in which they are imbedded, while by communication through the bones of the skull, its vibra- tions so affect the auditory apparatus^ as to awaken a con- sciousness of sound — a consciousness which alone results if the tuning-fork does not touch tHe body. The different sensations excited by etherial undulations on the unmodified integument and on those modified portions of it which constitute eyes (Principles of Biology, § 295) yield further illustrations. The Sun's rays falling on the hand T cause a sensation of heat but no sensation of light; and/ falling on the retina cause a sensation of light but no sensa- tion of heat. As Professor Tyndall has proved by experi- ment on himself, the jretina is msensible tqjkeat-rays of considerable concentration.
THE INDUCTIONS OF PSYCHOLOGY.
That the relation between an outer force and the feeling it arouses, varies quantitatively according to the of the body acted upon., there are many proofs, of whicla or two will suffice. The arched under-surfaoe o the foot experiences an intense sensation of tickling from.. gentle touch which generates a much feebler sensation o this kind elsewhere. Conversely,, the thick skin of the tee bears with comparatively little pain the long-continue < pressure of a hard prominence which would be intolerabl to the back of the hand. The feelings caused, "b; exposing different parts of the skin to the same heat, are not i] most cases conspicuously unlike in degree; but there is ou case in which they are. When drinking a liquid the heat c which is quite bearable by that part of the upper lip us~u.aU- immersed, it may be observed that if the lip is accidental! dipped deeper, so as to immerse a little of the outer slsim, sensation of scalding results.
We find, then, that the same external agent acting- o different peripheral organs, generates states of consciousneg which have in many cases no likenesses of kind whateve: and have in other cases immense unlikenesses of degree.
§ 83. The state of the part affected, as well as its structure has a share in determining the relation between outer and inner feeling. Already in the chapter on Physiology, it has been shown that the ratio borne by tt change set up in a nerve-termination to the feeling ellcitec varies with the local conditions. Obviously this involves concomitant variation in the ratio between the amoTixit < external force which initiates the nervous change, and. tl amount of feeling that eventually results. It will suffice 1 recall the several causes of the variation.
The temperature of the part is one of them. Betwee the state of local insensibility produced by excessive col- and the state of sensibility accompanying natural warmt! there arc states showing all gradations in the proportic THE RELATIVITY OF FEEJLmGS. £01 which the incident force bears toi the feeling called forth.
Local anemia affects this proportioia by diminishing the quantity of sensation which a given amount of outer action generates; and local hyperasrnia, by i increasing it — often extremely. Hypersemia, however, in; certain cases (pos- sibly by putting an obstacle between: the outer agent and the nerves to be affected) decreases the amount of feeling generated; as in the partial or complete loss of taste and smell caused by a bad cold.; The conation of the structures concerned as modified by previous discharge of their functions,! is a further cause of variation in the ratio between the objective actions and the subjective effects due to them. Sensory organs worn by strong excitements recently undergone, require greater ex- ternal forces to arouse the same amounts of internal feelina-s.
This is so with touches, tastes, smells,! as well as visual and auditory impressions. j One more cause of variation, occurring in a special class of cases, must be added. The sensatio^i that follows contact with matter hotter or colder than the body, depends less on s the temperature of the matter than ojn. the contrast between; its temperature and that: of.the bodyj On going into a warm;• bath or into cold water, the heat or /the cold seems greater than it does after a short interval, d-pring which the thermal state of the skin has approximate^, to that of the water. More striking still is the evidence yielded by cases in which the same tepid water feels either wirm or cold according to the temperature of the hand put into it; nay, in which it feels both warm and cold to thel two hands, if one has been much heated and the other mttch cooled.
§ 84. Yet another general fact remains. The relative motions of subject and object, modify, both qualitatively and quantitatively, the relations between incident forces and evoked feelings.
202 THE INDUCTIONS OF PSYCHOLOGY.
The instance of qualitative modification most easily ob- served,, is that produced in the pitch of a sound by the movement of the soiunding body towards, or away from,, the auditor. If, as an e:sgress train passes through a railway- station, the whistle liappens to be going, the tone heard by each person in the station, changes from a higher to a lower at the moment the engine goes by him. A still more marked change is perceivable if the auditor, seated in a train travelling with • considerable speed in one direction, is passed by a whisthing engine travelling rapidly in the opposite direction. jUnder such circumstances I have ob- served, at the moniep-t of passing, a fall in the pitch of the note amounting to a major third or even a fourth. How this is due to an alteration in the number of aerial pulses reaching the ear in a i given time, need not here be explained at length. It concerns us only to note that the quality of -the feeling produced by a sounding body is not the same when the body is approaching or receding as when, sta- tionary; and that ithe quality of the feeling changes i'with every change in the rate of approach or reces- sion. A remarkable illustration of analogous nature, has been disclosed by inquiries respecting the qualities of the lights radiated by different stars. Some years since it was' suggested that possibly the apparent colours of the stars iare.determined by their motions towards, or away from, 'the Earth at various velocities; and though this supposition^ has not turned out to be true, yet a truth akin to it has beei discovered. Though to the naked eye, the quality of the light emanating from each star is not appreciably affected by the star's velocity of approach to, or recession from, us; yet,j as examined through the spectro- scope, its quality proves i to be thus affected. Mr. Huggins has recently shown that the spectrum of Sirius differs from the spectrum he would yield were he stationary relatively to us; and differs in such w;ay as to show that he is moving away from us at a rate of more than two millions of miles