Popular Science Monthly/Volume 3/July 1873/On the Hereditary Transmission of Acquired Psychical Habits
|ON THE HEREDITARY TRANSMISSION OF ACQUIRED PSYCHICAL HABITS.|
By Dr. WILLIAM B. CARPENTER, LL. D., F. R. S.
PROCEEDING, now, to show that the tendency of modern Physiology is to prove the existence of a distinct causal relation between Physical changes in the Nervous System and definite modes of Mental action, it may be well for me to adduce, in limine, the positive evidence that all Mental activity is dependent on a Chemical reaction between the Blood and the Brain: for, although this is one of the best-established facts in Physiology, it is, I believe, taken very little account of by Metaphysicians.—The Brain is supplied with Blood by four Arterial trunks, which enter the cranial cavity at no great distance from one another, and then unite into the "Circle of Willis;" from which are given off the various branches that distribute arterial blood to every part of the brain-substance. After traversing this, the blood returns by the Veins, greatly altered in its chemical composition; especially as regards the loss of free oxygen, and its replacement by various oxy-compounds of carbon, hydrogen, phosphorus, etc., that have been formed by a process analogous to combustion. Now, if one, two, or three of the Arterial trunks be tied, the total supply of blood to the Brain is diminished; but, in virtue of the "Circle of Willis," no part is entirely deprived of blood; and the functional activity of the Brain is still maintained. If, however, the fourth artery is compressed so as to prevent the passage of blood, there is an immediate and complete suspension of activity; the animal becoming as unconscious as if it had been stunned by a severe blow, but recovering as soon as the blood is again allowed to flow through the artery. In fact, the "stunned" state produced by a blow on the head is not directly dependent upon the effect of that blow on the Brain, which may have sustained no perceptible injury whatever; the state of insensibility being due to the paralysis of the Heart and suspension of the Circulation, induced by the "shock:" and the like paralysis with the same result may be produced by a blow on the Epigastrium (acting on the great "solar plexus"of nerves), or some overpowering Mental emotion.—Again, there is a curious affection termed Hysteric Coma, which consists in the sudden supervention of complete insensibility, and the equally sudden and complete return of conscious intelligence, without any other indication of Brain-disorder. The insensibility may come on while the patient is talking, so as to interrupt the utterance of a sentence; and, the moment that it passes off, the series of words is taken up and completed, without the patient being aware that it has been interrupted. With our present improved knowledge of the action of the "vaso-motor" system of Nerves in producing local contractions of the Arteries, and of its liability to be influenced by those Emotional irregularities in which Hysteria essentially consists, we can scarcely doubt that this affection is due to a temporary disturbance of the Circulation through that agency.—Further, if the Blood transmitted to the Brain, though not deficient in quantity, be depraved in quality by the want of Oxygen and the accumulation of Carbonic acid (as happens in Asphyxia), there is a gradually increasing torpor of the Mental Faculties, ending in complete insensibility.
Thus the dependence of Mental activity of even the most elementary kind, upon the Physical changes kept up by the circulation of oxygenated Blood through the Brain, can be shown experientially to be just as direct and immediate as is the dependence of the Electric activity of a Galvanic battery upon the analogous changes taking place between its Metals and its exciting Liquid.—If we say that Electricity is the product of Chemical change in the one case, I see not how we can refuse to regard Thought as the product of Chemical change in the other; nor (in the view that all the Forces of Nature are simply expressions of Mind) do I see that we need entertain any repugnance to such a view. I do not say that it explains any Mental phenomenon. No sound Physicist would say that he can "explain" how it is that Electricity is generated by Chemical change; but he knows that such a relation of cause and effect exists between the two orders of phenomena, that every Chemical change is accompanied by an Electric disturbance; so that, whenever he witnesses Electric disturbance, he looks with assurance for some Chemical change as its Physical Cause. And in precisely the same sense, and in no other, I affirm that the Physiologist must regard some change in the Nervous substance of the Brain as the immediate Physical cause of all automatic Mental action. If this be admitted of Sensational consciousness (and how can it be denied?), we can scarcely help admitting it of Emotional; and, if of Emotional, why not of Ideational?
There is no part of our purely Physical activity, the relation of which to Physical conditions is more obvious and more intimate, than that Reproduction of past states of Consciousness; which—when supplemented by the recognition of them as having been formerly experienced—we call Memory. It is now very generally accepted by Physiologists as (to say the least) a probable doctrine, that any Idea which has once passed through the Mind, may be thus reproduced, at however long an interval, through the instrumentality of Suggestive action; the recurrence of any other state of Consciousness with which that Idea was originally linked by Association, being adequate to awaken it also from its dormant or latent condition, and to bring it within the "sphere of consciousness." And as our Ideas are thus linked in "trains" or "series," which further inosculate with each other like the branch-lines of a railway or the ramifications of an artery, so, it is considered, an Idea which has been "hidden in the obscure recesses of the mind" for years—perhaps for a lifetime—and which seems to have completely faded out of the conscious Memory (having never either recurred Automatically, or been found capable of recall by Volitional Recollection, or been recognized as a past experience when again brought before the mind), may be reproduced, as by the touching of a spring, through a nexus of Suggestions, which we can sometimes trace out continuously, but of which it does not seem necessary that all the intermediate steps should fall within our cognizance. Such a "reproduction" not unfrequently occurs when persons, revisiting certain scenes of their childhood, have found the renewal of the Sensorial impressions of places bring vividly back to their minds the remembrance of events which had occurred in connection with them; and which had not only been long forgotten by themselves, but, if narrated to them by others, would not have been recognized by them as having ever formed part of their own experience. And it is not a little significant that the basis of such Memories appears capable of being laid at a very early period of life; as in the two following cases, of which the first is recorded by Dr. Abercrombie, while the second was mentioned to me by the subject of it:
"A lady, in the last stage of chronic disease, was carried from London to a lodging in the country. There her infant daughter was taken to visit her, and, after a short interview, carried back to town. The lady died a few days after, and the daughter grew up without any recollection of her mother, till she was of mature age. At this time she happened to be taken into the room in which her mother died, without knowing it to have been so. She started on entering it, and, when a friend who was with her asked the cause of her agitation, replied, 'I have a distinct impression of having been in this room before, and that a lady who lay in that corner, and seemed very ill, leaned over me and wept.'"—(Inquiries concerning the Intellectual Powers, fifth edition, p. 120.)
"Several years ago, the Rev. S. Hansard, now Rector of Bethnal Green, was doing clerical duty for a time at Hurstmonceaux, in Sussex; and, while there, he one day went over with a party of friends to Pevensey Castle, which he did not remember to have ever previously visited. As he approached the gate-way, he became conscious of a very vivid impression of having seen it before; and he 'seemed to himself to see,' not only the gate-way itself, but donkeys beneath the arch, and people on the top of it. His conviction that he must have visited the Castle on some former occasion, although he had neither the slightest remembrance of such a visit, nor any knowledge of having ever been in the neighborhood previously to his residence at Hurstmonceaux, made him inquire from his mother if she could throw any light on the matter. She at once informed him that being in that part of the country when he was about eighteen months old, she had gone over with a large party, and had taken him in the pannier of a donkey; that the elders of the party, having brought lunch with them, had eaten it on the roof of the gate-way, where they would have been seen from below, while he had been left on the ground with the attendants and donkeys.—This case is remarkable for the vividness of the Sensorial impression (it may be worth mentioning that Mr. Hansard has a decidedly artistic temperament), and for the reproduction of details which were not likely to have been brought up in conversation, even if the subject of them had happened to hear the visit mentioned as an event of his childhood; and of such mention he has no remembrance whatever."
Now, there is very strong reason to believe that what is described as a storing-up of Ideas in the Memory is the Psychological expression of Physical changes in the Cerebrum, by which Ideational states are permanently registered or recorded; so that the "traces" left by them, although remaining so long outside the "sphere of consciousness" as to have seemed non-existent, may be revived again in full vividness under certain special conditions—just as the invisible impression left upon the sensitive paper of the Photographer is "developed" into a picture by the application of particular chemical substances. It must be freely admitted that we have at present no certain knowledge of the precise mode in which this record is effected; but, looking at the manner in which the Sensori-motor apparatus, which is the instrument of our bodily activity, shapes itself to the mode in which it is habitually exercised, we seem justined in assuming that the same thing is true of the Cerebrum, which is the instrument of our mental activity. For in no other way does it seem possible to account for the fact of very frequent occurrence, and noticed in a previous paper, that the presence of a Fever-poison in the blood—perverting the normal activity of the Cerebrum so as to produce Delirium—brings within the "sphere of consciousness" the "traces" of experiences long since past, of which, in the ordinary condition, there was no remembrance whatever.
The same occurrence has been noticed as a consequence of accidental blows on the head; though these more commonly occasion the loss than the recovery of a language. The following case of this kind is mentioned by Dr. Abercrombie, as having occurred in St. Thomas's Hospital:
"A man who had been in a state of stupor consequent upon an injury of the head, on his partial recovery spoke a language which nobody in the hospital understood, but which was soon ascertained to be Welsh. It was then discovered that he had been thirty years absent from Wales, and that, before the accident, he had entirely forgotten his native language. On his perfect recovery, he completely forgot his Welsh again, and recovered the English language." (Op. cit., p. 148.)
It seems perfectly clear, then, that, under what we cannot but term purely Material conditions, strictly Mental phenomena present themselves. It is common to the whole series of cases, that the Automatic play of the "Mechanism of Thought" does that which Volition is unable to effect. Whether it be the toxic condition of the Blood, or the simple excitement of the Cerebral Circulation generally, or the special direction of Blood to a particular part of the Brain, it is beyond our present power to tell; but, as all Brain-change is (like the action of any other mechanism) the manifestation of Force, the production of these unusual Mental phenomena, by the instrumentality of an unusual reaction between the Blood and the Brain-substance, is no more difficult of comprehension than that of ordinary forms of Psychical activity, which we have seen reason to regard as the results of the translation (so to speak) of one form of Force into another.
The intimacy of the relation between the Psychical phenomena of Memory and Physical conditions of the Brain is further shown, by the effect of Fatigue and the impaired Nutrition of Old Age in weakening the Memory, and of disease and Injury of the Brain in impairing or destroying it. Every one is conscious of the difference in the activity of the reproductive faculty in which Memory consists, according as his mind is "fresh," or his head feels "tired." The latter state, in which the Automatic activity and the directing power of the Will are alike reduced, is clearly dependent, like the feeling of muscular fatigue, on the deterioration of the Organ, or of the Blood, or of both combined, which results from the prolonged exercise of it: and it is especially in our inability to recollect something which we wish to call to mind, that this failure of power shows itself. An interval of repose completely restores the power, obviously (to the mind of the Physiologist) by the renovation of the worn-out Brain-tissue, and by the purification of the Blood that has become charged with the products of its "waste."—The impairment of the Memory in Old Age commonly shows itself in regard to new impressions; those of the earlier period of life not only remaining in full distinctness, but even, it would seem, increasing in vividness, from the fact that the Ego is not distracted from attending to them by the continual influx of impressions produced by passing events. The extraordinary persistence of early impressions, when the Mind seems almost to have ceased to register new ones, is in remarkable accordance with the Law of Nutrition referred to in a previous paper. It is when the Brain is growing, that the direction of its structure can be most strongly and persistently given to it. Thus the Habits of Thought come to be formed, and those Nerve-tracks laid down which (as the Physiologist believes) constitute the Mechanism of Association, by the time that the Brain has reached its maturity; and the Nutrition of the organ continues to keep up the same mechanism, in accordance with the demands upon its activity, so long as it is being called into use. Further, during the entire period of vigorous Manhood, the Brain, like the Muscles, may be taking on some additional growth, either as a whole, or in special parts; new tissue being developed and kept up by the nutritive process, in accordance with the modes of action to which the Organ is trained. And in this manner a store of "impressions" or "traces" is accumulated, which may be brought within the "sphere of consciousness" whenever the right suggesting-strings are touched. But, as the Nutritive activity diminishes, the "waste" becomes more rapid than the renovation; and it would seem that, while (to use a Commercial analogy) the "old-established houses" keep their ground, those later firms whose basis is less secure, are the first to crumble away—the Nutritive activity, which yet suffices to maintain the original structure, not being capable of keeping the subsequent additions to it in working order. This earlier degeneration of later-formed structures is a general fact perfectly familiar to the Physiologist.
The effects of Disease and Injury on the Memory are so marvellous and diverse, that only a very general indication of them can be here given. Cases are very common, in which the form of impairment just spoken of as characteristic of Old Age shows itself to a yet greater extent; the Brain being so disordered by attacks of Apoplexy or Epilepsy (for example), that it seems altogether incapable of retaining any new impressions, so that the patient does not remember any thing that passes from day to day; while the impressions of events which happened long before the commencement of his malady recur with greater vividness than ever. The Memory of particular classes of Ideas is frequently destroyed; that, for example, of a certain Language, or of some other branch of Knowledge, or of the patient's domestic or social relations. Thus a case was recorded by Dr. Beattie, of a gentleman, who, after a blow on the head, found that he had lost his knowledge of Greek, but did not appear to have suffered in any other way. A similar case has been recently communicated to me, in which a lad, who lay for three days insensible, in consequence of a severe blow on the head, found himself, on recovering, to have lost all the Music he had learned, though nothing else had been thus "knocked out" of him. Again, Dr. Abercrombie relates a curious case, on the authority of an eminent medical friend, in which a surgeon who suffered an injury of his head by a fall from his horse, on recovering from his insensibility gave minute directions in regard to his own treatment, but was found to have lost all remembrance of having a wife and children; and this did not return until the third day. Similar losses of particular Languages, and other kinds of acquired knowledge, have been noted as the results of Fevers.
One of the most remarkable results of recent Pathological research has been, the discovery of the dependence of the condition termed Aphasia, or "loss of memory of words," upon malnutrition of a certain part of the Cerebrum; and the tracing of this malnutrition back to an interruption in the supply of Blood. In this curious Mental infirmity (which often begins to show itself before there is any other evidence of Cerebral disorder, but which is now recognized as a most serious indication of impending mischief), the subject either forgets the words he wants for expressing his ideas, or he uses inappropriate words in their place. It is obvious that he knows what he wants to express, but cannot recall the words in which to convey that knowledge to others. There is no paralysis of speech, for his articulation is quite unaffected; so that he can repeat the words he wants, if they are suggested to him by others. In a case formerly under my observation, the Aphasia went on gradually but very slowly increasing for three or four years; showing itself at first as to only a few out-of-the-way words, but gradually increasing until no intelligible language seemed to be left, except that of swearing, which came forth in a torrent when any restraint was put on the patient's bodily activity, which continued very energetic until near the close of life. In another case recently mentioned to me by a medical friend, who was a near connection of the patient, the disease ran its course in a few months. Cases of this kind almost invariably terminate in Apoplexy.—Now, it may be said that we have here only the evidence of synchronous disease of the Brain and disorder of the Mind; so that the dependence of the latter upon the former is not made out. But the very curious discovery was made a few years ago, by Dr. J. Hughlings Jackson, that the locally-impaired nutrition of the Brain in these cases is usually attributable to "embolism" of the middle meningeal artery, whereby the passage of blood through it is greatly impeded; this "embolism" consisting in the plugging of the artery by a fibrinous clot brought from the heart, where it has been produced by valvular disease. In the second of the cases just referred to, the usual brain-lesion having been found, and the middle meningeal artery having been examined, the fons et origo of the mischief was found to be, not "embolism," but a morbid deposit on the inner wall of the artery, producing a corresponding .obstruction to the circulation. Looking, then, to the fact that immediate cessation of Mental activity is distinctly and unmistakably produced by the entire suspension of Blood-circulation through the Brain, how can the Physiologist refuse to recognize, in this local reduction of the Circulation, the Physical cause of that limited reduction of Psychical activity which so distinctly follows it?
But further, this singular fact, taken in connection with the recent great extension of our knowledge as to the local alterations in the calibre of the Arteries, which are produced through the "Vaso-motor" system of Nerves, obviously points to the probability that the limited but transient lapses of Memory just alluded to are due to a local reduction of the blood-supply in the part of the Cerebrum which ministers to the lost function; and that the sudden recovery which sometimes occurs is the result of the renewal of the normal circulation, through the giving way of the impacted clot, or the yielding of the spasmodically-constricted arterial wall.
Thus Dr. Rush, of Philadelphia, was acquainted with a person of considerable attainments, who, on recovering from a fever, was found to have lost all his acquired knowledge. When his health was restored, he began to apply himself to the Latin Grammar; and, while, one day, making a strong effort to recollect a part of his lesson, the whole of his lost impressions suddenly returned to his remembrance,so that he found himself at once in possession of all his former acquirements.—The like sudden restoration, after an equally sudden loss, occurred in another case in which all acquired knowledge was lost for a whole year; and in both the loss and the recovery there was clear evidence of strong Emotional excitement, which is well known to the Physiologist to have a most powerful control over the calibre of the Blood-vessels.
There is another class of familiar phenomena, which affords strong evidence of the dependence of the recording process upon Nutritive changes in the Brain. Every one is aware that what is rapidly learned—that is, merely committed to Memory—is very commonly forgotten as quickly, "one set of ideas driving out another." That thorough apprehension of what is learned, on the other hand, by which it is made (as it were) part of the Mental fabric, is a much slower process. The difference between the two is expressed by the colloquial term "cramming," as distinguished from "learning;" the analogy being obvious to the overloading the stomach with a mass of food too great to be digested and assimilated within a given time, so that a large part of it passes out of the body without having been applied to any good purpose in it. A part of this difference obviously consists in the formation of Mental Associations between the newly-acquired knowledge and that previously possessed; so that the new ideas become linked on with the old by "suggesting" chains. Such is especially the case, when we are applying ourselves to the study of any branch of knowledge, with the view of permanently mastering it; and here the element of Time is found practically to be very important. Thus, it is recorded of the late Lord St. Leonard's that, having (as Sir Edward Sugden) been asked by Sir T. F. Buxton what was the secret of his success, his answer was: "I resolved, when beginning to read Law, to make every thing I acquired perfectly my own, and never to go to a second thing till I had entirely accomplished the first. Many of my competitors read as much in a day as I read in a week; but, at the end of twelve months, my knowledge was as fresh as on the day it was acquired, while theirs had glided away from their recollection."—(Memoirs of Sir T. F. Buxton, chap, xxiv.)—In this Assimilating process, it is obvious that the new knowledge is (as it were) turned over and over in the Mind, and viewed in all its aspects; so that, by its coming to be not merely an addition to the old, but to interpenetrate it, the old can scrarcely be brought into the "sphere of consciousness," without bringing the new with it. But, from the considerations already adduced, it seems almost beyond doubt that the formation of this Associative nexus expresses itself in the Physical structure of the Brain, so as to create a mechanism whereby it is perpetuated so long as the Nutrition of the organ is normally maintained.
Another class of phenomena, now to be considered, seems to afford even more direct and cogent evidence of the dependence of Memory, in its simplest exercise, upon a registering process, that consists in some Nutritive modification of the Brain-tissue. In what we call "learning by heart"—which should be rather called learning by Sense, instead of by Mind—we try to imprint on our Memory a certain sequence of words, numbers, musical notes, or the like; the reproduction of these being mainly dependent upon the association of each item with that which follows it, so that the utterance of the former, or the picture of it in "the mind's eye," suggests the next. We see this plainly enough when children are set to learn a piece of poetry of which their minds do not take in the meaning; for the rhythm here affords a great help to the suggestive action; and nothing is more common than to hear words or clauses (transferred, perhaps, from some other part of the poem) substituted for the right ones, which are not only inappropriate but absolutely absurd in the lines as uttered. So, again, if the child is at fault, he does not think of the meaning of the sentence, and of what is wanted to complete it; but "tries back" over the preceding words, that their sound may suggest that of the word he desiderates. So there are older persons, with whom the pictured remembrance of the words and phrases is more suggestive; as in a case to be presently cited.—Now, in these instances, it is a familiar fact that what is thus learned but once, however perfectly, soon "goes out of the head," being only fixed there by continual repetition; and, as the Memory we are now considering is rather Sensorial than Ideational, this fact is confirmatory of the doctrine that seems probable on other grounds, of the superior (if not the exclusive) persistence of the latter. We seem distinctly able to trace the action of the recording process in this elementary form of Memory, in the help given in the "learning by heart" of a task, by repeating it the last thing at night; for every school-boy, who has to commit to memory fifty lines of Virgil, knows very well that, if he can "say them to himself," even slowly and bunglingly, just before going to sleep, he will be able to recite them much more fluently in the morning. The Physiologist sees here an obvious indication that the recording process has gone on without interruption by new impressions on the Sensorium, so that there has been time for the fixation of the last by Nutritive change. We have, indeed, a remarkable converse phenomenon, in the rapid fading away of a Dream, which, at the moment of waking, we can reproduce with extraordinary vividness; for the "trace" left by its details is soon obliterated by the new and stronger impressions made on our waking Consciousness, so that, a few hours afterward, we are often unable to revive more than the general outline of the Dream—and perhaps not even that, unless we have told it to another when it was fresh in our minds, of which act a "trace" would be left.
There are two classes of persons who are professionally called upon for great temporary exercises of Memory, viz., Dramatic Performers and Barristers. An actor, when about to perform a new "part," not only, commits it to memory, but "studies" it, so as to make it part of himself; and all really great actors identify themselves for the time with the characters they are performing. When a "part" has once been thoroughly mastered, the performer is usually able to go through it, even after a long interval, with very little previous preparation. But an actor is sometimes called upon to take a new "part" at very short notice; he then simply "learns it by heart," and speedily forgets it. A case of this kind is cited by Dr. Abercrombie, as having been the experience of a distinguished actor, on being called on to prepare himself in a long and difficult part, at a few hours' notice, in consequence of the illness of another performer. He acquired it in a very short time, and went through it with perfect accuracy; but immediately after the performance forgot it to such a degree that, although he performed the character for several days in succession, he was obliged every day to prepare it anew—not having time to go through the process of "studying" it, to which Mrs. Siddons used to give weeks or even months. When questioned respecting the mental process which he employed the first time he performed the part, he said that he entirely lost sight of the audience, and seemed to have nothing before him but the pages of the hook from which he had learned it; and that, if any thing had occurred to interrupt this illusion, he should have instantly stopped.—(Inquiry into the Intellectual Powers, fifth edition, p. 103.)
In the case of Barristers, who are called upon to "get up" the "briefs" which are supplied to them, to master the facts, to apply to them the principles of Law, and to present them in the Court in the form which they deem most advantageous to the "cause" they have undertaken to plead, the very highest faculties of mind are called into active exercise; but, in consequence, it would seem, of the want of previous connection with the "case" (of which they know nothing but what is set down in their "brief"), and of the complete cessation of that connection as soon as the decision has been given, they very commonly "forget all about it" so soon as they have transferred their Attention to their next brief. A curious instance of this kind was mentioned to the writer a few years ago by an eminent Barrister (since elevated to the Judicial Bench), whose great scientific attainments led to his being frequently employed in Patent-cases. A "heavy" case of this kind was placed in his hands, and he was reminded of having been engaged by the same parties in the same "case" when it had been first brought to trial about a year previously. He had not the slightest remembrance of its having ever been before him; none of the particulars of it seemed familiar to him; and he was only convinced that he really had taken part in the previous trial by finding the record of his engagement in his Fee-book. Even when he came to "get up" the case again, no remembrance of his former attention to it came within his "sphere of consciousness."
It seems, then, to admit of question whether every thing that passes through our Minds thus leaves its impress on their Material instrument; and whether a somewhat too extensive generalization has not been erected on a rather limited basis. For the doctrine of the indelibility of Memory rests on the spontaneous revival, under circumstances indicative of some change in the Physical condition of the Brain, of the long-dormant "traces" left by such former impressions as are referable to one or other of the three following categories: 1. States of Consciousness as to places, persons, language, etc., which were habitual with us in early life, and which were, therefore, likely to have directed the growth of the Brain; 2. Modes of Thought in which the formation of Associations largely participates, and which are likely to have modified the course of its maintenance by Nutrition after the attainment of maturity; or 3. Single Experiences of peculiar force and vividness, such as are likely to have left very decided "traces," although the circumstances of their formation were so unusual as to keep them out of ordinary associational remembrance. Thus a remarkable case is mentioned by Dr. Abercombie ("Intellectual Powers," fifth edition, p. 149) of a boy, who, at the age of four years, underwent the operation of trepanning, apparently in a state of perfect stupor, and who, after his recovery, retained no recollection either of the accident by which his skull was fractured, or of the operation, yet who, at the age of fifteen, during the delirium of fever, gave his mother an account of the operation and of the persons who were present at it, with a correct description of their dress, and other minute particulars of which it was scarcely possible that he could have acquired the knowledge from verbal information. Here it would seem that all the Mental power the patient then had must have been concentrated upon the impressions made upon his Sensorium, which were thus indelibly branded (as it were) upon his Organism; but that these "traces," being soon covered up by those resulting from the new experiences of restored activity, remained outside the "sphere of consciousness" until revived by a Physical change which reproduced the images of the objects that had left them.
The direct causal relation of Physical conditions to Mental states may be made still more clear by following out into some detail the phenomena of that peculiar form of Intoxication which is produced by Hashish—a preparation of Indian hemp used in the Levant for the purpose of inducing what is termed the fantasia. The action of this drug was very carefully studied some years ago by M. Moreau, Physician to the Bicetre, who had given great attention to the Psychology of Insanity, and whose special object was to throw light upon that subject by experimenting upon what he termed its artificial production. His treatise, "Du Hachisch, et de l'Aliénation Mentale" (Paris, 1845), is one which deserves the attentive study of such as desire to base their Psychology upon a comprehensive survey of facts.
One of the first appreciable effects of the Hashish, as of other Intoxicating agents, is the gradual weakening of that power of Volitionally controlling and directing the current of thought, the possession of which characterizes the vigorous mind. The individual feels himself incapable of fixing his attention upon any subject; the continuity of his thoughts being continually drawn off by a succession of disconnected ideas, which force themselves (as it were) into his mind, without his being able in the least to trace their origin. These speedily engross his attention, and present themselves in strange combinations, so as to produce the most impossible and fantastic creations. By a strong effort of the Will, however, the original thread of the ideas may still be recovered, and the interlopers may be driven away; their remembrance, however, being preserved, like that of a dream recalling events long since past. These lucid intervals progressively become shorter in duration, and can be less frequently procured by a voluntary effort; for the internal tempest becomes more violent, the torrents of disconnected ideas are so powerful as completely to arrest the attention, and the mind is gradually withdrawn altogether from the contemplation of external realities, being conscious only of its own internal workings. There is always preserved, however, a much greater amount of "self-consciousness" than exists in ordinary Dreaming; the condition rather corresponding with that in which the sleeper knows that he dreams, and, if his dream be agreeable, makes an effort to prolong it, being conscious of a fear lest he should by awaking cause the dissipation of the pleasant illusion.
It is another characteristic of the action of hashish that the succession of ideas has at first less of incoherence than in ordinary Dreaming, and the ideal events do not so far depart from possible realities; the disorder of the mind being at first manifested in errors of sense, in false convictions, or in the predominance of one or more extravagant ideas. These ideas and convictions are generally not altogether of an imaginary character, but are rather suggested by external impressions, these impressions being erroneously interpreted by the perceptive faculties, and giving origin, therefore, to fallacious notions of the objects which excited them. It is in that more advanced stage of the "fantasia' which immediately precedes the complete withdrawal of the mind from external things, and in which the self-consciousness and power of the Will are weakened, that this perverted impressibility becomes most remarkable, more especially as the general excitement of the Feelings causes the erroneous notions to have a powerful effect in arousing them.
"We become," says H. Moreau, "the sport of impressions of the most opposite kind; the continuity of our ideas may be broken by the slightest cause. We are turned, to use a common expression, by every wind. By a word or a gesture our thoughts may be successively directed to a multitude of different subjects with a rapidity and a lucidity which are truly marvellous. The mind becomes possessed with a feeling of pride corresponding with the exaltation of its faculties, of whose increase in energy and power it becomes conscious. It will be entirely dependent on the circumstances in which we are placed, the objects which strike our eyes, the words which fall on our ears, whether the most lively sentiments of gayety or of sadness shall be produced, or passions of the most opposite character shall be excited, sometimes with extraordinary violence; for irritation shall rapidly pass into rage, dislike to hatred and desire of vengeance, and the calmest affection to the most transporting passion. Fear becomes terror, courage is developed into rashness, which nothing checks, and which seems not to be conscious of danger, and the most unfounded doubt or suspicion becomes a certainty. The Mind has a tendency to exaggerate every thing; and the slightest impulse carries it along. Those who make use of the Hashish in the East, when they wish to give themselves up to the intoxication of the fantasia, take care to withdraw themselves from every thing which could give to their delirium a tendency to melancholy, or excite in them any thing else than feelings of pleasurable enjoyment; but they profit by all the means which the dissolute manners of the East place at their disposal."
The disturbance of the Perceptive Faculties is remarkably shown in regard to Time and Space. Minutes seem hours, and hours are prolonged into years; and at last all idea of Time seems obliterated, and the past and present are confounded together. M. Moreau mentions as an illustration, that on one evening he was traversing the passage of the Opera when under the influence of a moderate dose of Hashish. He had made but a few steps, when it seemed to him as if he had been there two or three hours; and, as he advanced, the passage appeared to him interminable, its extremity receding as he pressed forward. But he gives another more remarkable instance. In walking along the Boulevards, he has frequently seen persons and things at a certain distance presenting the same aspect as if he had viewed them through the large end of an opera-glass—that is, diminished in apparent size, and therefore suggesting the idea of increased distance. This erroneous perception of Space is one of the effects of the Amanita muscaria, an intoxicating Fungus used by the Tartars; a person under its influence being said to take a jump or a stride sufficient to clear the trunk of a tree when he wishes only to step over a straw or a small stick. Such erroneous perceptions are common enough among Lunatics, and become the foundations of fixed illusions; while in the person intoxicated by Hashish there is still a certain consciousness of their deceptive character.
Though all the Senses appear to be peculiarly impressible in this condition, yet that of Hearing seems the one through which the greatest influence may be exerted upon the Mind, especially through the medium of musical sounds. The celebrated artist, M. Théodore Gaultier, describes himself as hearing sounds from colors, which produced undulations that were perfectly distinct to him. But he goes on to say that the slightest deep sound produced the effect of rolling thunder; his own voice seemed so tremendous to him that he did not dare to speak out for fear of throwing down the walls, or of himself bursting like a bomb; more than five hundred clocks seemed to be striking the hour with a variety of tones, etc., etc. Of course, those individuals who have a natural or an acquired "musical ear" are the most likely to be influenced by the concord or succession of sweet sounds; and in such the simplest music of the commonest instrument, or even an air sung by a voice in a mediocre style, shall excite the strongest emotions of joy or melancholy, according as the air is cheerful or plaintive; the mental excitement being communicated to the body, and being accompanied with muscular movements of a semi-convulsive nature. This influence of music is not merely sensual, but depends, like that of other external impressions, upon the associations which it excites, and upon the habitual disposition to connect it with the play of the Imaginative faculties.
It is seldom that the excitement produced by the Hashish fixes itself upon any particular train of Ideas, and gives rise to a settled delusion; for in general one set of ideas chases another so rapidly, that there is not time for either of them to engross the attention of the intellect; more especially since (as already remarked) there is usually such a degree of self-consciousness preserved throughout, as prevents the individual from entirely yielding himself up to the suggestions of his ideal faculties. M. Moreau mentions, however, that on one occasion, having taken an overdose, and being sensible of unusual effects, he thought himself poisoned by the friend who had administered it, and persisted in this idea in spite of every proof to the contrary—until it gave way to another, namely, that he was dead, and was about to be buried; his self-consciousness, however, being yet so far preserved that he believed his body only to be defunct, his soul having quitted it. But when this is altogether suspended, as it seems to be by a larger dose, the erroneous ideas become transformed into convictions, taking full possession of the mind; although sudden gleams of common-sense burst through the mists of the imagination, and show the illusive nature of the pictures which the "Internal Senses" have impressed on the Sensorium. All this—as every one knows, who has made the phenomena of Insanity his study—has its exact representation in the different stages of Mental Derangement; the illusive ideas and erroneous convictions being in the first instance capable of being dissipated by a strong effort of the Will, gradually exerting a stronger and stronger influence on the general current of Thought, and at last acquiring such complete mastery over it that the Reason cannot be called into effective operation for the correction of the perverted Ideas.
Here, then, we have an extraordinary exaltation of the Automatic action of the Brain, manifesting itself in the rapidity and intensity of the current of Thought; while the controlling power of the Will is not only relatively, but absolutely reduced. And this modification of the normal form of mental activity is clearly referable to the perversion of the normal action of the Blood upon the Brain, which is due to the introduction of a new Physical agent into the former. The production of errors of Perception, arising from the tendency to magnification of the impressions actually made on the senses, is a peculiarly interesting feature of this perversion; which is clearly a mental misinterpretation, not at all corresponding to the mere double vision of the drunken man, which is an error of sense arising from the temporary want of adjustment of the axes of the eyes. And with this magnification there is connected a sentiment of happiness which attends all the operations of the mind.
"It is really happiness," says M. Moreau, "which is produced by the Hashish; and by this I imply an enjoyment entirely Moral, and by no means sensual, as we might be induced to suppose. This is surely a very curious circumstance, and some remarkable inferences might be drawn from it; this, for instance, among others—that every feeling of joy and gladness, even when the
cause of it is exclusively moral—that those enjoyments which are least connected with material objects, the most spiritual, the most ideal—may be nothing else than sensations purely physical, developed in the interior of the system, as are those procured by the Hashish. At least, so far as relates to that of which we are internally conscious, there is no distinction between these two orders of sensations, in spite of the diversity in the causes to which they are due; for the Hashish-eater is happy, not like the gourmand or the famished man when satisfying his appetite, or the voluptuary in gratifying his amative desires; but like him who hears tidings which fill him with joy, like the miser counting his treasures, the gambler who is successful at play, or the ambitious man who is intoxicated with success."
Most persons will be able to recall analogous states of exhilaration, and the reverse condition of depression, in themselves; the former being characterized by a feeling of general well-being, a sentiment of pleasure in the use of all the bodily and mental powers, and a disposition to look with enjoyment upon the present, and with hope to the future; while in the latter state there is a feeling of general but indefinable discomfort. Every exertion, whether Mental or Bodily, is felt as a burden; the present is wearisome, and the future is gloomy. These, like all other phases of Human Nature, are faithfully portrayed by Shakespeare. Thus Romeo gives expression to the feelings inspired by the first state:
"My bosom's lord sits lightly in his throne;
And, all this day, an unaccustomed spirit
Lifts me above the ground with cheerful thoughts."
(Romeo and Juliet, V., 1.
While the reverse state is delineated by Hamlet in his familiar soliloquy:
"I have of late—but wherefore I know not—lost all my mirth, foregone all custom of exercises; and, indeed, it goes so heavily with my disposition, that this goodly frame, the earth, seems to me a sterile promontory; this most excellent canopy, the air, look you—this brave o'erhanging firmament, this majestic roof fretted with golden fire, why it appears no other thing to me than a foul and pestilent congregation of vapors."—(Hamlet, II., 2.)
In the conditions here referred to, the same feelings of pleasure and discomfort attend all the operations of the mind—the merely Sensational and the Intellectual. In the state of exhilaration, we feel a gratification from sensations which at other times pass unnoticed, while those which are usually pleasurable are remarkably enhanced; and in like manner, the trains of Ideas which are started being which we before dwelt on with delight, now excite no feelings but those of pain, or at best of insouciance.attended with similar agreeable feelings, we are said to be under the influence of the pleasurable or elevating Emotions. On the other hand, in the state of depression we feel an indescribable discomfort from the very sensations which before produced the liveliest gratification; and the thoughts of the past, the present, and the future,
Now, there are many persons in whom these opposite Emotional states are induced by Meteorological conditions; the one by a dry, clear, bright atmosphere; the other by that close, damp, "muggy" state of the air, which seems to lay a "wet blanket" upon all their enjoyment, both bodily and mental. And precisely the same depressing influence is often experienced from deficient action of the liver, causing an accumulation of the materials of bile in the blood; and it is just as apparent to the Physician that the elimination of these by appropriate remedies, so as to restore the Blood to its normal purity, thereby removes the Moral depression, as it is that the introduction of a minute quantity of Hashish into the Blood produces a Moral exaltation.
In these days of eager competition, again, it is extremely common for a psychical state to be induced by the overtasking of the Brain, which every intelligent medical practitioner recognizes as essentially physical in its origin, but which yet manifests itself chiefly in moral, and not unfrequently, also, in intellectual perversion. The excess of activity is followed, as its natural result, by a state of depression; in which the subject of it looks at every thing, past, present, and future, in a gloomy light, as through a darkened glass. His whole life has been evil; he has brought ruin on his affairs; his dearest friends are in league to injure him. At first this moral perversion extends itself only to a misinterpretation of actual occurrences, which only differs in degree from that which we observe in persons of a morose temper. But, with the advance of the disorder, the mind dwells on its own morbid imaginings, till they come to take the place of actual facts; and in this way hallucinations are generated—i. e., creations of the imagination, which are accepted as real occurrences. Now, here there is no primary intellectual perversion; the reasoning powers are not disturbed; the patient can discuss with perfect sanity any question that does not touch his morbid feelings; but the representations shaped by his own mind, under the influence of these feelings, being received as truths to the exclusion of his common-sense, all his actions are based on those erroneous data. This condition is merely an intensification of that just described; and the Physician can no more doubt that it depends upon an unhealthy condition of the bodily frame, than that the delirium of fever and the fantasia of Hashish are dependent upon the presence of a poison in the blood.
The Psychologist who neglects such phenomena as these, merely because the inferences drawn from them by the Physiologist have a dangerous flavor of "materialism," seems to me just as blameworthy as the Physiologist who ignores the facts of consciousness, when they do not happen to fit in with his own conclusions. The true Psychologist is he who lays the foundations of his science broad and deep in the whole constitution of the individual man, and his relations to the World external to him; and aims to build it up with the materials furnished by Experience of every kind, mental and bodily, normal and abnormal; ignoring no fact, however strange, that is attested by valid evidence, and accepting none, however authoritatively sanctioned, that will not stand the test of thorough scrutiny.
It is very easy, and doubtless very pleasant, to dispose of "Cerebration" by a sneer; but those who do so may be fairly called upon in the first place to acquaint themselves with a class of facts which they have never studied; and, when they have examined them, may be challenged to give some better and more scientific rationale of them than that here offered. I should myself rejoice to welcome any new light that metaphysics can throw upon such questions as the following:
1. What other than "Physical Antecedents" excite those states of Consciousness which we call Sensations, and the Pleasure and Pain associated with them?
2. Does not all Psychological as well as Physiological probability point to the identity of the Sensorial instrumentality through which we become conscious (1) of a present Impression, and (2) of a remembered Sensation?
3. If, then, a Visual perception be immediately dependent on a Physical change in the Sensorium, excited (through the optic nerve) by a Physical change in the Retina, is it not probable that a Visual conception depends on a corresponding Physical change in the Sensorium, called forth (through the "nerves of the internal senses") by a Physical change in the cortical substance of the Cerebrum?
4. As Sensational Consciousness can be excited by "Physical Antecedents," why should not Ideational and Emotional?
5. Is there not Psychological as well as Physiological evidence that the excitement of the Ideational consciousness is the result of a series of Physical changes taking place in the Cerebrum, as the action of a Mechanism created by its preformed Habits? In what other way are the facts (admitted by Psychologists of all schools) to be accounted for, which indicate the suggestion of one Idea by another through a chain of Associations, some links of which lie outside the "sphere of consciousness?"
6. Is it conceivable that such an oft-recurring phenomenon as the loss of some branch of acquired Knowledge, after a blow on the head or a fever, is a mere coincidence? If not, on what other hypothesis than that of "Physical antecedence" can the blow be the cause of this Mental effect?
7. Is there not as much evidence that "Physical Antecedents" may produce Moral Pleasure and Pain, as that they produce Sensorial Pleasure and Pain?
8. If in any case we admit Physical antecedence as the Cause (in the ordinary language of Science) of Mental Phenomena, why not in every case of automatic Mental activity?—whether this be left altogether uncontrolled, or be in subjection to the will.
9. When a series of Physical sequences comes to be established by the Habitual action of the Cerebrum in particular modes directed or permitted by the Will, is it not consonant to all Physiological probability that the tendency to similar sequences should be hereditarily transmitted, like the tendency to bodily habits?—Contemporary Review.