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 language 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 pleasurable emotion to discharge itself in partially exciting pleasurable 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 consciousness 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 consciousness 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 produced by a particular pleasure (or pain) is much more like the total consciousness produced by other particular pleasures (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 predominance 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 conversely 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 indifferent feelings. The sights and. sounds., the sensations 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. Ordinarily, therefore, that background of consciousness which constitutes our " state of mind/' as distinguished from our passing sensations, perceptions, and ideas, is a neutral compound in which the aggregate of perpetually-nascent pleasurable feelings is fused with the aggregate of perpetuallynascent 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 combustion 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 counterpart 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 becoming, 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 discharge, 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 discharge, 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 faintlyaroused 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 consciousness, 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.
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 disturbances.
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 constitutionally 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 alimentary 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 external 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 accompanying 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 illustrate 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 find here a farther verification of the hypothesis. Blood being needful for the performance of function, and the activity of function being, other things equal, proportionate to the supply of blood, it naturally happens that a continuance of the supply after the demand for function has ceased, causes undue readiness to resume function. When, among the data of psychology, WQ dealt with relations between blood and nervous action and feeling, we saw that an excess of blood at the periphery of the nervous system, as in an inflamed part of the skin, is accompanied by extreme sensitiveness: the molecular change then set up in the disturbed end of a nerve, is so great as to send an unduly powerful discharge to the point where feeling is aroused. If we transfer these conditions from periphery to centre, we at once see how this abnormal genesis of ideas results. As nervous discharges of all kinds are diffused and re-diffused until they affect the whole nervous system, we must regard every sensation, every thought, every emotion, as a propagator of disturbances, strong or weak, throughout the cerebral masses. The reverberations reaching plexuses in their ordinary states, draw from them but feeble reactions, and accompanying faint additions to the general body of consciousness. But when the reverberations reach plexuses made unduly sensitive by the presence of much blood, the reactions of their elements are unduly strong — the gushes of nervous fluid liberated, escaping along the habitual lines of discharge, arouse the correlative states of consciousness not faintly but vividly; and these, standing out from the background of consciousness, become the predominant thoughts and feelings.
If these physical processes are extended to the whole brain, there result multitudinous vivid ideas not of one kind but of many kinds. All the cerebral plexuses being rendered by excess of blood unduly sensitive, as well as Initiators of unduly strong disturbances,, consciousness becomes a torrent of intense thoughts and feelings; and if instead of congestion we hare inflammation., order and proportion among the thoughts and feelings are quite lost — there is delirium.
§ 264. From temporary insanity, partial or general,, of the kind caused by partial or general derangements of circulation., congestive or inflammatory, through the cerebral plexuses, we pass to the kind of permanent insanity that ensues when such derangements of circulation become permanent.
If nutrition of a cerebral plexus is much raised, or much altered in kind, by great excess of blood, the thoughts and feelings initiated are likely to be intensified to a degree that constitutes them illusions — we get monomania. Carrying out the analogy above indicated, we may say that as a touch on an inflamed surface of skin arouses as much feeling as a cut would ordinarily do; so a hyperseinic nervous plexus excited by some slight disturbance, reacts as violently as it would ordinarily do only after a very strong disturbance: the correlative psychical efiect being the production of ideas that are unduly vivid — so vivid sometimes as to be scarcely, if at all, distinguishable from perceptions. Supposing this state lasts, structural changes occur in all the tissues implicated. Greatly exalting for a time the rate of molecular change, producing thickening and deposits, and leaving a degradation of structure inconsistent with the due discharge of function, the hyperaBmia may, after making the correlative psychical states unduly vivid, end in enfeebling them — so entailing a changed form of mental affection.
If a chronic vascular derangement, or derangement of nutrition otherwise caused, extends to many or all of the cerebral plexuses, general insanity would seem fairly inferable. Should it be said that a deviation from the normal EVIDENCE FROM ABNORMAL VARIATIONS.
rafce of tissue-metamorphosis throughout the cerebrum at large, either by increase or decrease, would seem only to necessitate a corresponding exaltation or depression of all the mental powers, and not a derangement of them,, I reply as before (§ 260) that derangement of them is implied by any disturbance of the proportions among the intensities of states of consciousness., and that such disturbance is caused bv anything that modifies them all indiscriminately. If the strengths of the nervous discharges are so raised that those passing along the less permeable channels set up molecular changes,, and arouse correlative feelings, almost or quite as strong as the sensations aroused by peripheral stimuli, the gradations that normally exist among states of consciousness in respect of their degrees of vividness and degrees of cohesion,, are either destroyed or seriously altered — judgment beingperverted to a proportionate extent. And a perversion of judgment will likewise result if, from an opposite physical cause, some of the states of consciousness become too faint or disappear.
It is needful to add that though thus far chronic vascular derangements, and derangements of local nutrition entailed by them., have been named as causes of insanity, the implication that they are the only causes is by no means intended. Effete matters may, if they accumulate in the blood, produce molecular disturbances in the nervous centres through which they are continually carried; and molecular disturbances so set- up will have for their concomitants disorders of the mental states. Or instead of a normal product of decomposition that has not been duly excreted, some introduced virus., or some morbid matter arising from constitutional disease, may,, by thus acting as an irritant, perturb the ct^rents of thoughts and feelings. That an impure blood is thus a possible, and indeed a probable, cause of insanity, we find good reason for believing, ~* § 265. For we "bring on a species of temporary insanity by E R 610 PHYSICAL SYNTHESIS..
put tins1 certain poisons into the blood. Substances which like opium and hashish, exalt the rate of molecular change in the nervous centres, so intensify the feelings and ideas as to cause illusions.
I need not follow out in detail the parallelism between the effects of increased pressure of nervous fluid produced bj these drills and increased pressure otherwise produced. Here, as before, there is such exaltation of ideal feelings as brings them near to real feelings in distinctness; sucli strengthening- of the relations among them as causes failing memories to arise with clearness; sucli facility in the formation of remote and complex connexions of thoughts as constitutes a transfigured imagination; and such widening of consciousness as changes its quiet flow into a flood.
One thing only will I draw attention to — the verificatior yielded of a foregoing hypothesis respecting the genesis o: " states of mind." As a corollary from the laws of association translated into terms of nervous action, we concluded that when the pressure of nervous fluid is low, the diffused discharges will be so distributed that the faintly revivec feelings of pain will preponderate; that when the nervous pressure is up to par, the aggregate of feelings indistinctly awakened, pleasurable and painful, will form a neutral compound; and that when the pressure is high, the pleasurable elements of consciousness, relatively as well as positively increased in their amount, will constitute a sense of happiness. Here it is to be observed that artificial^ happiness ii produced bvj^rtific^ The delightfu reveries of the opiiim^eater constitute the temptation whicl he finds it so difficult to resist. And similarly with Indiai jeuTEK tf It is real happiness which is produced by hashish/ says 1L More an.
§ 26o, To complete the outline of the evidence furnishe< by abnormal variations, a few words must be added on th s, These change the nervous a€tions and EVIDENCE FROM ABNORMAL VARIATIONS.
correspondingly, change the states of xnind. Are the changes they work interpre table as agreeing with the foregoing general doctrine? In great measure,, I think,, if not wholly.
It is admitted as holding generally of these various agents — alcohol, ether, chloroform, nitrous oxide, &c. — that when their anaestEetic effects begin, the highest nervous actions are the first to be arrested; and that the artificial paralysis implicates in descending order the lower, or simpler, or better-established nervous actions. Incipient intoxication shows itself in a failure to form involved and abstract relation of ideas, while it remains possible to form simpler relations. In the anaesthesia produced for surgical purposes, we have less opportunity of observing that the like happens; but assuming that it does so, we find all the successive symptoms conformable in their order to the hypothesis. According to M. Plourens and Dr. Snow, as quoted and, on the whole, endorsed by Dr. Anstie, the aether-narcosis produces the loss of — -" 1. The local sensi-" bility of extreme parts, and the control of certain musclea situated in those parts. 2. The intellectual powers. 3. The* power of co-ordination of the locomotive organs generally.! 4. The power of perceiving sensory impressions, even from parts little removed from the spinal centres. '5. The power of breathing. 6. The movements of vegetative life — e.g., of | the heart, intestines, &c" Here loss of the intellectual powers is placed after loss of sensibility cc of extreme parts "; but this discrepancy is due to the fact that paralysis of the higher intellectual powers, necessarily inconspicuous under the circumstances, is not specifically named, even where observable; and that only when the perceptions become confused are the intellectual powers set down as lost. The experiments, both with ether and chloroform, show clearly that some incoherence of thought is the first noticeable effect.
Making this correction of the statement, we may say that anaesthetics stop first the discharges along the incipient lines of nervous communication; next the discharges along lines a little better formed; and so on, until finally they stop the discharges along the fully-established lines. Limiting ourselves for brevity to the two extremes, we see that on the one hand, incoherence among the more involved thoughts implies that those least permeable channels of nervous discharge that have been formed by the comparatively-few experiences of the individual, have become impermeable • while, on the other hand, when the functions of the visceral nervous system cease, the implication is that discharges no longer pass even through those most permeable channels which have been inherited, in a ready-organized form, from an ancestry that runs back not simply through numberless individuals, but through numberless species.
Though the effects of anaesthetics thus yield confirmation of the belief that lines of nervous communication become permeable in proportion as the discharges through them are strong and frequent, they present some apparent obstacles to it. How is the preliminary stage of excitement, and even mental exaltation, reconcilable with the- argument? How are the differential effects of different anaesthetics to be explained? How does it happen that in some cases sensation is abolished while there continues some consciousness of things around? I believe there are answers to these questions; but this general exposition, would be too much encumbered by including them in it.* § 267. I have reserved till the last what needs to be said in answer to objections which critical readers have probably made, now to one and now to another, of the several foregoing interpretations. This I have done with the intention of ultimately pointing out that the interpretations 'must be taken not separately but together. The many ^causes of variation at work, interfere with one another in ^multitudinous ways and degrees — each is influenced by all and all by each.
* See Appendix.
EVIDENCE FROM: ABNORMAL VAIUATIONS. 613 Due co-ordination of any set of nervous discharges, aad production of the appropriate combination of mental states accompanying it, depends, primarily, on the existence of fitly-organized nervous plexuses in fitly-adjusted molecular states; and this pre-supposes that the approximately-adapted structures which the individual inherited, have had their adaptation completed by his own activities. It depends, secondarily, on the general supply of nervous fluid; and the physical processes and accompanying psychical states will vary according as the pressure of nervous fluid is high, or moderate, or low. And it depends, tertiarily, on ihe extent to which nervous fluid is being at the time drawn off by other discharges — to the viscera, to the muscles, or to other parts of the nervous system. Along with these general deter-"*' mining causes have to be taken into account many more special determining causes — the state of the blood as rich or poor, as well or ill crated, as freed or not freed from this or that waste matter; the state of the blood as containing morbid products or foreign substances; the supply of blood to the plexuses concerned, which depends partly on habit, as involving frequent or infrequent action of them, and partly onj the character of the blood vessels, as contractile or the re-j verse; and, lastly, the state of these plexuses as modified ] by chronic derangements of nutrition due to local inflaniina-* tion and its seqiielce.
Remembering that aU these co-operative causes have to be taken into account, we shall, I think, see little difficulty in reconciling the various anomalies with the general principle set forth.
CHAPTER X.
HESULTS- § 268. A not unsatisfactory fulfilment of the anticipation with which we set out has, I think, been reached. In the General Synthesis mental development,, traced up from its beginnings, was represented 'as a correspondence between inner and outer actions, that extends in Space and in Time., while it increases in Speciality,, in Generality, and in Complexity. The, Special Synthesis^ carried further this interpretation of mental development, by showing how the advancing correspondence, when translated into the more familiar terms of Reflex Action, Instinct, Memory, Reason, Feeling, and Will, is comprehensible as a continuous process naturally caused. And in the Physical Synthesis just concluded, this continuous process naturally caused has been interpreted as a cumulative result of physical ^actions that conl^erve being supposed to have the molecular structure;ind properties which, at the beginning of this work, we xmnd such numerous reasons for assigning to it; we have nferred from, established laws of motion, that the molecular phiange wrought in it by every discharge it conveys, leaves ft in a state for conveying a subsequent like discharge with resistance. This^being the universal^ law of nervous action, explains the universal law of intelligence. In the foregoing chapters we have compared the various corollaries