Given a nervous system in any constitutional condition, what will happen to the rest if one portion of it is greatly excited? Supposing large demands to be made on the general supply of nervous fluid by a powerful discharge in one direction, what will be the effects on discharges in other directions? The question is not by any means simple; for ordinarily a nervous action is accompanied by an invigorated pulse and a raised respiration, whence it results that being better supplied with materials, the nervous system generates more nervous fluid. Up to a certain point, therefore, the efflux in the performance of some one kind of function, has the effgct of increasing instead of diminishing the general efflux. This is especially the case with those modes of nervous expenditure which bring with them increased ex- citements of the sensations and emotions. Nevertheless, EVIDENCE FKQ1I NOEMAL VARIATIONS. 595 there is reason to suspect that some effects such as the hypothesis implies are produced.
When muscular effort is suddenly pushed: to excess, say- by running a long way at full speed or by climbing' a moun- tain till forced to desist by want of breath., the power of thinking is appreciably diminished. Though it remains easy to unite ideas in simple combinations, it becomes difficult to unite them in complex combinations — a meta- physical question demands a greater mental effort than can be made. The emotions undergo- a like enfeeblement — a temporary apathy ensues. That is to say, an excessive ab- straction of nervous fluid diminishes so much the general pressure throughout the nervous system, that no dis- charges take place along the less permeable channels. It is true that the aeration of the blood falls in arrear, and that diminished genesis of nervous fluid thus becomes a part- cause of these effects; but we shall find evidence that it is only a part-cause. For the alleged connexion of phenomena is quite clearly shown on passing to those nervou's discharges which have not increased excitements of feelings as their concomitants, Wheii the muscles and glands of the alimentary canal are at work", the heart and lungs have their actions raised; and the evolu- tion of nervous energy is thereby favoured. But their activity brings no such increased evolution of nervous energy as does that of the locomotive organs; since their activity neither yields direct sensations, nor incidentally entails more vivid and varied perceptions and ideas, with the feelings immediate and remote which they imply. Consequently, the abstraction of nervous fluid by the stomach when food has been put into it, is an almost un- compensated deduction from the general supply of nervous fluid. In youth the mental effect is not much feltf but in middle life and after, we see that the digestion of a heavy meal (at least in the absence of social excitements) entail*- such a diminution of pressure throughout the nervoiv f"f)g PHYSICAL SYNTHESIS.
svsvm, that only the simple and coherent relations of ideas are termed with facility. Processes.of thought which imply discharges through involved sets of channels that are not \vrv permeable, are performed with.difficulty. There is a disinclination to mental work as well as to bodily work; and not uncommonly, the overflow so far fails that even the simpler relations of ideas becoming faint and confused, there presently follows the unconsciousness of sleep.
§ 260. More special antagonisms, akin to these in their natures and effects, may be traced. A very strong emotion makes such a draught on the supply of nervous fluid as to incapacitate the intellect throughout much of its higher sphere. Conceptions that come in the lines of production and discharge of the emotion, may be formed with facility and vividness (though in some persons even these fall into confusion); but conceptions unconnected with the occasion, especially of kinds that are abstract or involved, become for the time impossible. There seems some reason to think that, conversely, great expenditure of energy in intense intellectual action is accompanied by a temporary diminution of emotional sensibility. It may be suspected, too, that long-continued intellectual absorption, of a kind which has little or no emotional excitement for its accom- paniment, leads to a permanent enfeeblement of the emo- tions. Indeed, there is an antagonism of different faculties that appears to necessitate this— competing with one another as they do for supplies of energy and materials from the same general stock.
But the^nost interesting and instructive solution belono-- ing to this group, is that afforded of the aberrations which emotions produce among intellectual processes. When we rem*mVer that the plexuses co-operating in any involved act, are made up of multitudinous channels of various of permeability, we shall see that the mental act can be properly performed only when the discharges through EVIDENCE FROM NORMAL VARIATIONS. 597 the co-operating plexuses take place under the normal pressure. As before shown, the least permeable plexuses are the first to become functionally inactive as the pressure diminishes; and here it is to be observed that for the same reason-, the least permeable parts of each plexus will as the pressure diminishes have their discharges appreciably en- feebled before the more permeable parts. But right mental adjustments, implying accurate nervous co-ordinations,, depend on the maintenance of due proportions among the strengths of the discharges j and anything that alters these proportions interferes with the adjustments. Necessarily, then, a strong emotion disturbs the intel- lectual balance. Both derangements of simple percep- tions and derangements of complex judgments show us this. Among derangements of perceptions, I may refer in passing to those which great fear produces— the misinterpretation of visual impressions being in this state of mind very marked. But examples that are better, because the effects are numerically measurable, occur among those who play games of skill. If when about to make a stroke at billiards arty emotion has been raised, by the presence of spectators or otherwise, failure is very apt to result; and this though the heart's action and the mus- cular tone are not appreciably affected. The cause is clear. Success presupposes great exactness in the ratios among the many combined contractions, and in the adapta- tion of them all to the many combined impressions; the ratios among which have also to be exactly appreciated. But when a great draught of nervous fluid to the parts of the nervous system occupied in an emotion, has diminished the pressure under which these sensory and motor discharges are made through the co-operating plexuses, the ratios among the actions of their parts are so far changed that the co-ordination becomes imperfect. That among those higher intellectual actions we class as judgments, a like disturbance leads to a like derangement, is obvious.
598 PHYSICAL SYNTHESIS.
Take a case. To decide which of several results will most likely follow some step,, saj in a negociation, implies repre- sentations of them as caused by complex motives and circumstances. These several results rise in consciousness with different degrees of vividness and pertinacity; and to believe that one of them will qccur, is to feel that this one persists in consciousness more decidedly than the others — the greater persistence being determined by some prepon- derance of kindred experiences. But due proportion among the tendencies of these several representations to arise and continue, depends on the maintenance of the normal pressure of nervous fluid. This is interfered with both locally and generally by strong emotions. In the first place, the particular emotions excited in reference to the question at issue, perturb the judgment by increasing the discharge along those lines of representation that further their own excitement. In the second place, these particular emotions, or any other emotions, perturb the judgment by affecting the general supply of nervous fluid. Under the high tide which extreme elation implies, the nervous discharges pass easily along the less permeable channels, and the feebler representations are raised more nearly to a level with stronger ones, so that discrimination becomes less easy; whence it happens that improbable results of a desired kind are thought probable. While under a state of depressed spirits, judgment fails because the proportions among the nervous discharges are interfered with in an opposite way.
§ 261. Fully to explain these last derangements of judg- ment, however, we must take into account one further class of variations among the mental activities. In entering on this class, I find tlgte opportunity of redeeming a promise made in § 128; where, after propounding an hypothesis respecting the natures of pleasures and pains, it was hinted that some verification would be furnished at a later stage of the argument. We saw reason to think " that while Plea- EVIDENCE FROM NORMAL VASIATJONS.
sures and Pains are partly constituted of those local and conspicuous elements of feeling directly aroused by special stimuli, they are largely, if not mainly, composed of secon- dary elements of feeling aroused indirectly by diffused stimulation of the nervous system/' Here we have to con- sider what further reasons for thinking this are now apparent; and what further solutions they introduce us to.
That every special pleasure or pain, peripheral or central, does produce a diffused effect is clear. I do not mean simply that this is a corollary from the foregoing argument: I mean that it is shown experimentally. Beyond the familiar fact that each strong sensation or emotion affects the action of the heart, we have the fact that the accompanying gush of nervous fluid, spreading along all the vaso-motor nerves, changes the state of the arteries throughout the whole body. Much more then does it spread through those more directly- related parts of the nervous system which are seats of con- scious actions. What remains here to inquire, then, is how far the diffusion is specialized-according to the nature of the feeling.
In tracing out the genesis of emotions, we hare seen that the plexuses which co-ordinate certain clustered impres- sions received from without, with the combined actions appropriate to them, are necessarily entangled with kindred plexuses that perform kindred co-ordinations. We have inferred that when a particular plexus is excited, it immediately excites the mass of kindred plexuses with which it is organized — the result being that the feelings proper to this mass of excited plexuses are aroused, and in their multitudinous but vague aggregate, constitute the accompanying emotion. But the pi*)ees£ does not end here. This mass of plexuses thus excited has to discharge itself; and the question now to be asked is — what general directions will its discharge take, and what*will be the general nature of the produced feelings? The answer is this. Any excited mass /jf plexuses will discharge itself 600 PHYSICAL SYNTHESIS.
into the masses of plexuses with which it has most in common, and these into others similarly related to them. Xow the plexuses in which one kind of pleasurable emotion is seated,, must have much in common with the plexuses in which some other kinds of pleasurable emotions are seated; seeing that the external plexuses of phenomena to which ihev refer have much in common, and frequently occur together. The smiles and tones expressing affection are approached by those expressing approbation. The natural language of approbation is a good deal like the natural lan- guage of benevolent feeling. The manner of one who acts kindly to us is similar to the manner which on many past occasions has preceded and accompanied the receipt of kindnesses, and arouses a dim consciousness of pleasures that are followed — perhaps of agreeable society, perhaps of beautiful scenery, perhaps of field sports, perhaps of all these. Evidently, then, the tendency is for any one pleasur- able emotion to discharge itself in partially exciting plea- surable emotions of other kinds; so that, more or less remotely, all kinds of pleasures come to be ideally presented in a faint- way. But since besides being faint they are so multitudinous and so various in quality, the resulting consciousness is wholly indefinite; and can be described only as a sense of satisfaction or of happiness. Similarly with pains. A particular form of bodily suffering produced by internal derangement, is linked by near resemblance with other forms of bodily suffering so produced; some of these by their localities and qualities are associated in conscious- ness with the pains caused by external cuts and bruises; some of these, again, are connected in experience with the impressid&s received from creatures about to inflict bodily injuries on us; and, of such impressions, some have much in common with those received from men who, if they do not threatSn bodily injuries, are likely to do something that will be positively or negatively painful to us in its ultimate results. Hence a special pain, or rather the liberated EVIDENCE FROM NORMAL VARIATIONS.
GUI nervous fluid which occurrence of it implies,, discharging itself along lines of least resistance, partially awakens ideas of associated pains, and through these a vaguer conscious- ness of pains more distantly related, till by its ultimate diffusion there is generated an obscure feeling of discomfort or nnhappiness. And hence results the peculiarity before pointed out (§ 128) that the total consciousness pro- duced by a particular pleasure (or pain) is much more like the total consciousness produced by other particular plea- sures (or pains) than is the initial feeling which arouses it like the initial feelings which arouse them.
By joining with this conception the inferences reached above, it becomes possible to account for a remaining psychical variation of a seemingly mysterious nature. How does it bappen that a certain state of the circulation, or of the blood, or of both, causes in consciousness a predomi- nance of painful ideas and a vague feeling of misery; while another state of the circulation, or of the blood, or of both, causes a predominance of pleasurable ideas, backed by a general sense of content or even of exhilaration — and this, too, in presence of the same circumstances? We find no answer in any recognized laws of psychical action; nor does any answer seem deducible from established principles of nerve-physiology. We shall, however, find an answer in that synthesis of the two which we are here pursuing.
The diffusion of nervous discharges is ordinarily still wider than I have just described it to be — is indeed, as at first indicated, universal. When the initial feelings are of a pleasurable kind, the diffusion is predominantly in the direction of associated pleasurable feelings; and con- versely when the initial feelings are of a painful ikind. But the diffusion is never exclusively in either direction, because the initial feelings of either kind are not separable from accompanying initial feelings which, if not of the Apposite kind, are still of a kind related to both — namely, the in- different feelings. The sights and. sounds., the sensations 602 PHYSICAL SYNTHESIS.
of toucli and muscular tension, which form the mass of our definite consciousness from moment to moment, are connected in experience with both pleasures and pains; and, unless when combined in particular ways, they tend to arouse ideas of the one kind as much as ideas of the other. Ordi- narily, therefore, that background of consciousness which constitutes our " state of mind/' as distinguished from our passing sensations, perceptions, and ideas, is a neutral com- pound in which the aggregate of perpetually-nascent plea- surable feelings is fused with the aggregate of perpetually- nascent painful feelings. Equanimity may be compared to white light, which, though composed of numerous colours is colourless -, while pleasurable and painful moods of raind may be compared to the modifications of light that result from increasing the proportions of some rays or decreasing the proportions of others. " But how/' it will be asked, " does this interpretation help us to explain the genesis of mental depression and mental elation? Following out the simile, may it not be said that as, by intensifying combus- tion we increase the brilliancy of the light without altering its quality, so, by exalting nervous action we ought simply to increase the vividness of consciousness without altering its quality?" The reason for answering in the negative is this. One of the laws of association is that the stronger the feelings connected in experience the more easily does the one subsequently recall the other; and the physical counter- part of this law we have found to be that the channel taken by any nervous discharge is made the more permeable in proportion as the discharge is augmented. Now pains in general are more intense than pleasures in general. Indeed, as was pointed out when treating of the two (§ 123), pains of the positive order result from the excesses of actions which in lower degrees are pleasurable. Other things being e^ual then (that is to say the comparison being made between pleasures and pains belonging to the same class and that have been similarly repeated in experience) the idea of EVIDENCE FKOM NORMAL VARIATIONS.
a pain follows its antecedent into consciousness more readily than the idea of pleasure. On the other hand., pleasures, though less intense, are more numerous, and are more variously linked with other elements of mind. Setting out *nth the mass of indifferent feelings forming our ordinary perceptive consciousness, we may say that in the " state of mind " which is its background, there are nascent a small number of painful feelings that are strong, a larger number of pleasurable feelings that are less strong, and a much larger number of feelings that are but slightly pleasurable: their respective cohesions with the indifferent feelings be- coming, for the reasons given, less strong as they become more numerous. This being understood, we have now onlv to ask how variations of pressure throughout the nervous system will operate, to reach the solution we seek. When this pressure is high, the less permeable lines of dis- charge, answering to the feebler associations among our pleasurable feelings, are filled by the escaping currents; and the aggregate of faintly-aroused ideas of pleasure grows in extent as well as in strength. As the pressure augments, this diffused consciousness of pleasure bears an increasing ratio to the diffused consciousness of pain — so producing in its ascending degrees a sense of satisfaction, of happiness, of joy for which no reason can be given. Contrariwise, a failing genesis of nervous fluid being followed by cessation of the efflux along the least permeable lines of dis- charge, and presently by its cessation along lines next to those in their small permeability, it inevitably happens that as the pressure goes on diminishing, the aggregate of faintly- aroused pleasurable feelings bears a decreasing ratio to * the aggregate of faintly-aroused painful feelings. And when the pressure has fallen so low that currents pass only along very permeable lines, it results that the diffused con- sciousness, or vague background to our definite perceptions and ideas, comes to be composed mainly of the aggregate of faintly-aroused painful feelings — so producing gloom, and groundless fear, and despair.
11 CHAPTER TSL EVIDENCE PROM ABNORMAL VARIATIONS.
§ 262. In cause and consequence, the case with which the last chapter closed introduces us to variations of the abnormal class. States of body and mind like that described, passing from the temporary into the permanent, become nervous disorders; presenting us with many psychical disturbances accompanying many physical dis- turbances.
We need not trace over again in these cases the relation between decreased genesis of nervous fluid and failure of mental power; for uhe relation is substantially the same as that which we have traced in the aged and in the constitu- tionally sluggish — there is a like failure of memory, a like narrowing of the area of consciousness as shown in diminished excursiveness of thought, and a like want of readiness in moments of emergency. But there is one other trait of nervous debility not hitherto pointed out, on which a few words may be said. I refer to the accompanying change of character, or modification of the emotional nature.
Even Small ebbings of the nervous fluid, hardly to be called abnormal, produce slight modifications of this kind; as is observable in children. The highest co-ordinating plexuses being in them the least developed, children betray more quickly than adults any defective action of these plexuses; and they habitually do this when the general EVIDENCE PROM ABNORMAL VARIATIONS.
nervous pressure is below par. Sluggishness of tlie ali- mentary canal, implying partial failure of nutrition and decreased genesis of energy, is accompanied by fret-fulness — bv a display of the lower impulses uncontrolled by the higher. It is, however, in the chronically nervous, whose blood, deteriorated in quality and feebly propelled, fails to keep up a due activity of molecular change, that we see this connexion of phenomena most clearly. The irascibility of persons in this state is matter of common remark:; and irascibility implies a relative inactivity of the superior feelings. It results when a sudden discharge, sent by a pain or annoyance through those plexuses which adjust the conduct to painful and annoying agencies, is unaccompanied by a discharge through those plexuses which adjust the conduct to many circumstances instead of a single circumstance. That deficient genesis of nervous fluid accounts for this loss of emotional balance, is a corollary from all that has gone before. The plexuses which co-ordinate the defensive and destructive activities, and in which, are seated the accompanying feelings of antagonism and anger, are inherited from all antecedent races of creatures, and are therefore well organized — so well organized that the child in arms shows them in action. But the plexuses which, by connecting and co-ordinating a variety of inferior plexuses, adapt the behaviour to a variety of ex- ternal requirements, have been but recently evolved; so that, besides being extensive and intricate, they are formed of much less permeable channels. Hence when the nervous system is not fully charged, these latest and highest structures are the first to fail. Instead of being instant to act, their actions, if appreciable at all, come te«o late to check the actions of the subordinate structures.* * A verification seems worth naming. The sleeplessness often accom- panying nervous debility, sometimes leads to the occasional use of morphia. A dose of this in excess of the need, causing undue nervous stimulation and waste, with excitement of the heart's action, entails a subsequent 60G PHYSICAL SYNTHESIS.
§ 263. Among deviations towards a jnorbid state of an opposite kind, let us first note such as are apt to follow temporary and local excitations. These arise by insensible steps out of the ordinary deviations which accompany functional activity.
Each pare of the brain, like the brain as a whole and like everv other organ, requires., during the performance of its function, an augmented supply of blood. And of a cerebral plexus it doubtless holds as of a gland, that when called into action, the stimulus sent to the vase-motor centre is reflected to the vessels of the part, in such. way as to cause dilatation of them. During health y and when the plexus has not been too persistently exercised, this increased flow of blood through it ceases soon after the demand ceases. But extreme continuance of the activity even, in those who have well-toneci vascular systems, and very moderate continuance of it in those whose vascular systems are relaxed, leads to local congestion lasting for a considerable time; and there then occurs a more or less abnormal genesis of the correlative states of consciousness. Strong persons frequently illus- trate this truth on landing after a sea- voyage of a day or two: they continue for hours to have illusive perceptions of rolling and pitching. And where, as in nervous people^ the cerebral blood vessels easily lose their contractility, it commonly happens that a subject discussed, or even thought about with, much intensity, monopolizes consciousness for a long time afterwards in spite of efforts to exclude it — often thus preventing sleep. Such congestions of cerebral plexuses have various degrees of duration — occasionally "?
further decrease in the genesis of nervous fluid; and the irritability and. explosiveness then "become greater than nsuaL There seems reason to think, too, that habitual opium-eaters, in whom this worst state has been made dxronic, have these highest plexuses almost paralyzed;. and are thus bereft of fehe feelings whicn should adjust their conduct in its remoter and more complex bearings. The lives of Coleridge and De Quincey furnish.
EVIDENCE FROM ABNORMAL VARIATIONS. 607 causing perversions in the currents of ideas persistent enough to attract the notice of those around. We