"I followed the sluggish current of hyaline material issuing from globules of most primitive living substance. Persistently it followed its way into s.p.a.ce, conquering, at first, the manifold resistances opposed to it by its watery medium. Gradually, however, its energies became exhausted, till at last, completely overwhelmed, it stopped, an immovable projection stagnated to death-like rigidity. Thus for hours, perhaps, it remained stationary, one of many such rays of some of the many kinds of protoplasmic stars. By degrees, then, or perhaps quite suddenly, help would come to it from foreign but congruous sources. It would seem to combine with outside complemental matter drifted to it at random. Slowly it would regain thereby its vital mobility. Shrinking at first, but gradually completely restored and reincorporated into the onward tide of life, it was ready to take part again in the progressive flow of a new ray." {56}

To return to the end of the last paragraph but one. If this is so - but I should warn the reader that Professor Hering is not responsible for this suggestion, though it seems to follow so naturally from what he has said that I imagine he intended the inference to be drawn, - if this is so, a.s.similation is nothing else than the communication of its own rhythms from the a.s.similating to the a.s.similated substance, to the effacement of the vibrations or rhythms heretofore existing in this last; and suitability for food will depend upon whether the rhythms of the substance eaten are such as to flow harmoniously into and chime in with those of the body which has eaten it, or whether they will refuse to act in concert with the new rhythms with which they have become a.s.sociated, and will persist obstinately in pursuing their own course. In this case they will either be turned out of the body at once, or will disconcert its arrangements, with perhaps fatal consequences. This comes round to the conclusion I arrived at in "Life and Habit," that a.s.similation was nothing but the imbuing of one thing with the memories of another. (See "Life and Habit," pp. 136, 137, 140, &c.)

It will be noted that, as I resolved the phenomena of heredity into phenomena of personal ident.i.ty, and left the matter there, so Professor Hering resolves the phenomena of personal ident.i.ty into the phenomena of a living mechanism whose equilibrium is disturbed by vibrations of a certain character - and leaves it there. We now want to understand more about the vibrations.

But if, according to Professor Hering, the personal ident.i.ty of the single life consists in the uninterruptedness of vibrations, so also do the phenomena of heredity. For not only may vibrations of a certain violence or character be persistent unperceived for many years in a living body, and communicate themselves to the matter it has a.s.similated, but they may, and will, under certain circ.u.mstances, extend to the particle which is about to leave the parent body as the germ of its future offspring. In this minute piece of matter there must, if Professor Hering is right, be an infinity of rhythmic undulations incessantly vibrating with more or less activity, and ready to be set in more active agitation at a moment's warning, under due accession of vibration from exterior objects. On the occurrence of such stimulus, that is to say, when a vibration of a suitable rhythm from without concurs with one within the body so as to augment it, the agitation may gather such strength that the touch, as it were, is given to a house of cards, and the whole comes toppling over. This toppling over is what we call action; and when it is the result of the disturbance of certain usual arrangements in certain usual ways, we call it the habitual development and instinctive characteristics of the race. In either case, then, whether we consider the continued ident.i.ty of the individual in what we call his single life, or those features in his offspring which we refer to heredity, the same explanation of the phenomena is applicable. It follows from this as a matter of course, that the continuation of life or personal ident.i.ty in the individual and the race are fundamentally of the same kind, or, in other words, that there is a veritable prolongation of ident.i.ty or oneness of personality between parents and offspring. Professor Hering reaches his conclusion by physical methods, while I reached mine, as I am told, by metaphysical. I never yet could understand what "metaphysics" and "metaphysical" mean; but I should have said I reached it by the exercise of a little common sense while regarding certain facts which are open to every one. There is, however, so far as I can see, no difference in the conclusion come to.

The view which connects memory with vibrations may tend to throw light upon that difficult question, the manner in which neuter bees acquire structures and instincts, not one of which was possessed by any of their direct ancestors. Those who have read "Life and Habit" may remember, I suggested that the food prepared in the stomachs of the nurse-bees, with which the neuter working bees are fed, might thus acquire a quasi-seminal character, and be made a means of communicating the instincts and structures in question. {58} If a.s.similation be regarded as the receiving by one substance of the rhythms or undulations from another, the explanation just referred to receives an accession of probability.

If it is objected that Professor Hering's theory as to continuity of vibrations being the key to memory and heredity involves the action of more wheels within wheels than our imagination can come near to comprehending, and also that it supposes this complexity of action as going on within a compa.s.s which no unaided eye can detect by reason of its littleness, so that we are carried into a fairy land with which sober people should have nothing to do, it may be answered that the case of light affords us an example of our being truly aware of a mult.i.tude of minute actions, the hundred million millionth part of which we should have declared to be beyond our ken, could we not incontestably prove that we notice and count them all with a very sufficient and creditable accuracy.

"Who would not," {59a} says Sir John Herschel, "ask for demonstration when told that a gnat's wing, in its ordinary flight, beats many hundred times in a second? or that there exist animated and regularly organised beings many thousands of whose bodies laid close together would not extend to an inch? But what are these to the astonishing truths which modern optical inquiries have disclosed, which teach us that every point of a medium through which a ray of light pa.s.ses is affected with a succession of periodical movements, recurring regularly at equal intervals, no less than five hundred millions of millions of times in a second; that it is by such movements communicated to the nerves of our eyes that we see; nay, more, that it is the difference in the frequency of their recurrence which affects us with the sense of the diversity of colour; that, for instance, in acquiring the sensation of redness, our eyes are affected four hundred and eighty-two millions of millions of times; of yellowness, five hundred and forty-two millions of millions of times; and of violet, seven hundred and seven millions of millions of times per second? {59b} Do not such things sound more like the ravings of madmen than the sober conclusions of people in their waking senses? They are, nevertheless, conclusions to which any one may most certainly arrive who will only be at the pains of examining the chain of reasoning by which they have been obtained."

A man counting as hard as he can repeat numbers one after another, and never counting more than a hundred, so that he shall have no long words to repeat, may perhaps count ten thousand, or a hundred a hundred times over, in an hour. At this rate, counting night and day, and allowing no time for rest or refreshment, he would count one million in four days and four hours, or say four days only. To count a million a million times over, he would require four million days, or roughly ten thousand years; for five hundred millions of millions, he must have the utterly unrealisable period of five million years. Yet he actually goes through this stupendous piece of reckoning unconsciously hour after hour, day after day, it may be for eighty years, often in each second of daylight; and how much more by artificial or subdued light I do not know. He knows whether his eye is being struck five hundred millions of millions of times, or only four hundred and eighty-two millions of millions of times. He thus shows that he estimates or counts each set of vibrations, and registers them according to his results. If a man writes upon the back of a British Museum blotting-pad of the common nonpareil pattern, on which there are some thousands of small s.p.a.ces each differing in colour from that which is immediately next to it, his eye will, nevertheless, without an effort a.s.sign its true colour to each one of these s.p.a.ces. This implies that he is all the time counting and taking tally of the difference in the numbers of the vibrations from each one of the small s.p.a.ces in question. Yet the mind that is capable of such stupendous computations as these so long as it knows nothing about them, makes no little fuss about the conscious adding together of such almost inconceivably minute numbers as, we will say, 2730169 and 5790135 - or, if these be considered too large, as 27 and 19. Let the reader remember that he cannot by any effort bring before his mind the units, not in ones, but in millions of millions of the processes which his visual organs are undergoing second after second from dawn till dark, and then let him demur if he will to the possibility of the existence in a germ, of currents and undercurrents, and rhythms and counter rhythms, also by the million of millions - each one of which, on being overtaken by the rhythm from without that chimes in with and stimulates it, may be the beginning of that unsettlement of equilibrium which results in the crash of action, unless it is timely counteracted.

If another objector maintains that the vibrations within the germ as above supposed must be continually crossing and interfering with one another in such a manner as to destroy the continuity of any one series, it may be replied that the vibrations of the light proceeding from the objects that surround us traverse one another by the millions of millions every second yet in no way interfere with one another. Nevertheless, it must be admitted that the difficulties of the theory towards which I suppose Professor Hering to incline are like those of all other theories on the same subject - almost inconceivably great.

In "Life and Habit" I did not touch upon these vibrations, knowing nothing about them. Here, then, is one important point of difference, not between the conclusions arrived at, but between the aim and scope of the work that Professor Hering and I severally attempted. Another difference consists in the points at which we have left off. Professor Hering, having established his main thesis, is content. I, on the other hand, went on to maintain that if vigour was due to memory, want of vigour was due to want of memory. Thus I was led to connect memory with the phenomena of hybridism and of old age; to show that the sterility of certain animals under domestication is only a phase of, and of a piece with, the very common sterility of hybrids - phenomena which at first sight have no connection either with each other or with memory, but the connection between which will never be lost sight of by those who have once laid hold of it. I also pointed out how exactly the phenomena of development agreed with those of the abeyance and recurrence of memory, and the rationale of the fact that p.u.b.erty in so many animals and plants comes about the end of development. The principle underlying longevity follows as a matter of course. I have no idea how far Professor Hering would agree with me in the position I have taken in respect of these phenomena, but there is nothing in the above at variance with his lecture.

Another matter on which Professor Hering has not touched is the bearing of his theory on that view of evolution which is now commonly accepted. It is plain he accepts evolution, but it does not appear that he sees how fatal his theory is to any view of evolution except a teleological one - the purpose residing within the animal and not without it. There is, however, nothing in his lecture to indicate that he does not see this.

It should be remembered that the question whether memory is due to the persistence within the body of certain vibrations, which have been already set up within the bodies of its ancestors, is true or no, will not affect the position I took up in "Life and Habit." In that book I have maintained nothing more than that whatever memory is heredity is also. I am not committed to the vibration theory of memory, though inclined to accept it on a prima facie view. All I am committed to is, that if memory is due to persistence of vibrations, so is heredity; and if memory is not so due, then no more is heredity.

Finally, I may say that Professor Hering's lecture, the pa.s.sage quoted from Dr. Erasmus Darwin on p. 26 of this volume, and a few hints in the extracts from Mr. Patrick Mathew which I have quoted in "Evolution, Old and New," are all that I yet know of in other writers as pointing to the conclusion that the phenomena of heredity are phenomena also of memory.

CHAPTER VI

Professor Ewald Hering "On Memory."

I will now lay before the reader a translation of Professor Hering's own words. I have had it carefully revised throughout by a gentleman whose native language is German, but who has resided in England for many years past. The original lecture is ent.i.tled "On Memory as a Universal Function of Organised Matter," and was delivered at the anniversary meeting of the Imperial Academy of Sciences at Vienna, May 30, 1870. {63} It is as follows:-

"When the student of Nature quits the narrow workshop of his own particular inquiry, and sets out upon an excursion into the vast kingdom of philosophical investigation, he does so, doubtless, in the hope of finding the answer to that great riddle, to the solution of a small part of which he devotes his life. Those, however, whom he leaves behind him still working at their own special branch of inquiry, regard his departure with secret misgivings on his behalf, while the born citizens of the kingdom of speculation among whom he would naturalise himself, receive him with well-authorised distrust. He is likely, therefore, to lose ground with the first, while not gaining it with the second.

The subject to the consideration of which I would now solicit your attention does certainly appear likely to lure us on towards the flattering land of speculation, but bearing in mind what I have just said, I will beware of quitting the department of natural science to which I have devoted myself hitherto. I shall, however, endeavour to attain its highest point, so as to take a freer view of the surrounding territory.

It will soon appear that I should fail in this purpose if my remarks were to confine themselves solely to physiology. I hope to show how far psychological investigations also afford not only permissible, but indispensable, aid to physiological inquiries.

Consciousness is an accompaniment of that animal and human organisation and of that material mechanism which it is the province of physiology to explore; and as long as the atoms of the brain follow their due course according to certain definite laws, there arises an inner life which springs from sensation and idea, from feeling and will.

We feel this in our own cases; it strikes us in our converse with other people; we can see it plainly in the more highly organised animals; even the lowest forms of life bear traces of it; and who can draw a line in the kingdom of organic life, and say that it is here the soul ceases?

With what eyes, then, is physiology to regard this two-fold life of the organised world? Shall she close them entirely to one whole side of it, that she may fix them more intently on the other?

So long as the physiologist is content to be a physicist, and nothing more - using the word "physicist" in its widest signification - his position in regard to the organic world is one of extreme but legitimate one-sidedness. As the crystal to the mineralogist or the vibrating string to the acoustician, so from this point of view both man and the lower animals are to the physiologist neither more nor less than the matter of which they consist. That animals feel desire and repugnance, that the material mechanism of the human frame is in chose connection with emotions of pleasure or pain, and with the active idea-life of consciousness - this cannot, in the eyes of the physicist, make the animal or human body into anything more than what it actually is. To him it is a combination of matter, subjected to the same inflexible laws as stones and plants - a material combination, the outward and inward movements of which interact as cause and effect, and are in as close connection with each other and with their surroundings as the working of a machine with the revolutions of the wheels that compose it.

Neither sensation, nor idea, nor yet conscious will, can form a link in this chain of material occurrences which make up the physical life of an organism. If I am asked a question and reply to it, the material process which the nerve fibre conveys from the organ of hearing to the brain must travel through my brain as an actual and material process before it can reach the nerves which will act upon my organs of speech. It cannot, on reaching a given place in the brain, change then and there into an immaterial something, and turn up again some time afterwards in another part of the brain as a material process. The traveller in the desert might as well hope, before he again goes forth into the wilderness of reality, to take rest and refreshment in the oasis with which the Fata Morgana illudes him; or as well might a prisoner hope to escape from his prison through a door reflected in a mirror.

So much for the physiologist in his capacity of pure physicist. As long as he remains behind the scenes in painful exploration of the details of the machinery - as long as he only observes the action of the players from behind the stage - so long will he miss the spirit of the performance, which is, nevertheless, caught easily by one who sees it from the front. May he not, then, for once in a way, be allowed to change his standpoint? True, he came not to see the representation of an imaginary world; he is in search of the actual; but surely it must help him to a comprehension of the dramatic apparatus itself, and of the manner in which it is worked, if he were to view its action from in front as well as from behind, or at least allow himself to hear what sober-minded spectators can tell him upon the subject.

There can be no question as to the answer; and hence it comes that psychology is such an indispensable help to physiology, whose fault it only in small part is that she has. .h.i.therto made such little use of this a.s.sistance; for psychology has been late in beginning to till her fertile field with the plough of the inductive method, and it is only from ground so tilled that fruits can spring which can be of service to physiology.

If, then, the student of nervous physiology takes his stand between the physicist and the psychologist, and if the first of these rightly makes the unbroken causative continuity of all material processes an axiom of his system of investigation, the prudent psychologist, on the other hand, will investigate the laws of conscious life according to the inductive method, and will hence, as much as the physicist, make the existence of fixed laws his initial a.s.sumption. If, again, the most superficial introspection teaches the physiologist that his conscious life is dependent upon the mechanical adjustments of his body, and that inversely his body is subjected with certain limitations to his will, then it only remains for him to make one a.s.sumption more, namely, that this mutual interdependence between the spiritual and the material is itself also dependent on law, and he has discovered the bond by which the science of matter and the science of consciousness are united into a single whole.

Thus regarded, the phenomena of consciousness become functions of the material changes of organised substance, and inversely - though this is involved in the use of the word "function" - the material processes of brain substance become functions of the phenomena of consciousness. For when two variables are so dependent upon one another in the changes they undergo in accordance with fixed laws that a change in either involves simultaneous and corresponding change in the other, the one is called a function of the other.

This, then, by no means implies that the two variables above-named - matter and consciousness - stand in the relation of cause and effect, antecedent and consequence, to one another. For on this subject we know nothing.

The materialist regards consciousness as a product or result of matter, while the idealist holds matter to be a result of consciousness, and a third maintains that matter and spirit are identical; with all this the physiologist, as such, has nothing whatever to do; his sole concern is with the fact that matter and consciousness are functions one of the other.

By the help of this hypothesis of the functional interdependence of matter and spirit, modern physiology is enabled to bring the phenomena of consciousness within the domain of her investigations without leaving the terra firma of scientific methods. The physiologist, as physicist, can follow the ray of light and the wave of sound or heat till they reach the organ of sense. He can watch them entering upon the ends of the nerves, and finding their way to the cells of the brain by means of the series of undulations or vibrations which they establish in the nerve filaments. Here, however, he loses all trace of them. On the other hand, still looking with the eyes of a pure physicist, he sees sound waves of speech issue from the mouth of a speaker; he observes the motion of his own limbs, and finds how this is conditional upon muscular contractions occasioned by the motor nerves, and how these nerves are in their turn excited by the cells of the central organ. But here again his knowledge comes to an end. True, he sees indications of the bridge which is to carry him from excitation of the sensory to that of the motor nerves in the labyrinth of intricately interwoven nerve cells, but he knows nothing of the inconceivably complex process which is introduced at this stage. Here the physiologist will change his standpoint; what matter will not reveal to his inquiry, he will find in the mirror, as it were, of consciousness; by way of a reflection, indeed, only, but a reflection, nevertheless, which stands in intimate relation to the object of his inquiry. When at this point he observes how one idea gives rise to another, how closely idea is connected with sensation and sensation with will, and how thought, again, and feeling are inseparable from one another, he will be compelled to suppose corresponding successions of material processes, which generate and are closely connected with one another, and which attend the whole machinery of conscious life, according to the law of the functional interdependence of matter and consciousness.

After this explanation I shall venture to regard under a single aspect a great series of phenomena which apparently have nothing to do with one another, and which belong partly to the conscious and partly to the unconscious life of organised beings. I shall regard them as the outcome of one and the same primary force of organised matter - namely, its memory or power of reproduction.

The word "memory" is often understood as though it meant nothing more than our faculty of intentionally reproducing ideas or series of ideas. But when the figures and events of bygone days rise up again unbidden in our minds, is not this also an act of recollection or memory? We have a perfect right to extend our conception of memory so as to make it embrace involuntary reproductions, of sensations, ideas, perceptions, and efforts; but we find, on having done so, that we have so far enlarged her boundaries that she proves to be an ultimate and original power, the source, and at the same time the unifying bond, of our whole conscious life.

We know that when an impression, or a series of impressions, has been made upon our senses for a long time, and always in the same way, it may come to impress itself in such a manner upon the so-called sense-memory that hours afterwards, and though a hundred other things have occupied our attention meanwhile, it will yet return suddenly to our consciousness with all the force and freshness of the original sensation. A whole group of sensations is sometimes reproduced in its due sequence as regards time and s.p.a.ce, with so much reality that it illudes us, as though things were actually present which have long ceased to be so. We have here a striking proof of the fact that after both conscious sensation and perception have been extinguished, their material vestiges yet remain in our nervous system by way of a change in its molecular or atomic disposition, {69} that enables the nerve substance to reproduce all the physical processes of the original sensation, and with these the corresponding psychical processes of sensation and perception.

Every hour the phenomena of sense-memory are present with each one of us, but in a less degree than this. We are all at times aware of a host of more or less faded recollections of earlier impressions, which we either summon intentionally or which come upon us involuntarily. Visions of absent people come and go before us as faint and fleeting shadows, and the notes of long-forgotten melodies float around us, not actually heard, but yet perceptible.

Some things and occurrences, especially if they have happened to us only once and hurriedly, will be reproducible by the memory in respect only of a few conspicuous qualities; in other cases those details alone will recur to us which we have met with elsewhere, and for the reception of which the brain is, so to speak, attuned. These last recollections find themselves in fuller accord with our consciousness, and enter upon it more easily and energetically; hence also their apt.i.tude for reproduction is enhanced; so that what is common to many things, and is therefore felt and perceived with exceptional frequency, becomes reproduced so easily that eventually the actual presence of the corresponding external stimuli is no longer necessary, and it will recur on the vibrations set up by faint stimuli from within. {70} Sensations arising in this way from within, as, for example, an idea of whiteness, are not, indeed, perceived with the full freshness of those raised by the actual presence of white light without us, but they are of the same kind; they are feeble repet.i.tions of one and the same material brain process - of one and the same conscious sensation. Thus the idea of whiteness arises in our mind as a faint, almost extinct, sensation.

In this way those qualities which are common to many things become separated, as it were, in our memory from the objects with which they were originally a.s.sociated, and attain an independent existence in our consciousness as ideas and conceptions, and thus the whole rich superstructure of our ideas and conceptions is built up from materials supplied by memory.

On examining more closely, we see plainly that memory is a faculty not only of our conscious states, but also, and much more so, of our unconscious ones. I was conscious of this or that yesterday, and am again conscious of it to-day. Where has it been meanwhile? It does not remain continuously within my consciousness, nevertheless it returns after having quitted it. Our ideas tread but for a moment upon the stage of consciousness, and then go back again behind the scenes, to make way for others in their place. As the player is only a king when he is on the stage, so they too exist as ideas so long only as they are recognised. How do they live when they are off the stage? For we know that they are living somewhere; give them their cue and they reappear immediately. They do not exist continuously as ideas; what is continuous is the special disposition of nerve substance in virtue of which this substance gives out to-day the same sound which it gave yesterday if it is rightly struck. {71} Countless reproductions of organic processes of our brain connect themselves orderly together, so that one acts as a stimulus to the next, but a phenomenon of consciousness is not necessarily attached to every link in the chain. From this it arises that a series of ideas may appear to disregard the order that would be observed in purely material processes of brain substance unaccompanied by consciousness; but on the other hand it becomes possible for a long chain of recollections to have its due development without each link in the chain being necessarily perceived by ourselves. One may emerge from the bosom of our unconscious thoughts without fully entering upon the stage of conscious perception; another dies away in unconsciousness, leaving no successor to take its place. Between the "me" of to-day and the "me" of yesterday lie night and sleep, abysses of unconsciousness; nor is there any bridge but memory with which to span them. Who can hope after this to disentangle the infinite intricacy of our inner life? For we can only follow its threads so far as they have strayed over within the bounds of consciousness. We might as well hope to familiarise ourselves with the world of forms that teem within the bosom of the sea by observing the few that now and again come to the surface and soon return into the deep.

The bond of union, therefore, which connects the individual phenomena of our consciousness lies in our unconscious world; and as we know nothing of this but what investigation into the laws of matter teach us - as, in fact, for purely experimental purposes, "matter" and the "unconscious" must be one and the same thing - so the physiologist has a full right to denote memory as, in the wider sense of the word, a function of brain substance, whose results, it is true, fall, as regards one part of them, into the domain of consciousness, while another and not less essential part escapes unperceived as purely material processes.

The perception of a body in s.p.a.ce is a very complicated process. I see suddenly before me, for example, a white ball. This has the effect of conveying to me more than a mere sensation of whiteness. I deduce the spherical character of the ball from the gradations of light and shade upon its surface. I form a correct appreciation of its distance from my eye, and hence again I deduce an inference as to the size of the ball. What an expenditure of sensations, ideas, and inferences is found to be necessary before all this can be brought about; yet the production of a correct perception of the ball was the work only of a few seconds, and I was unconscious of the individual processes by means of which it was effected, the result as a whole being alone present in my consciousness.

The nerve substance preserves faithfully the memory of habitual actions. {72} Perceptions which were once long and difficult, requiring constant and conscious attention, come to reproduce themselves in transient and abridged guise, without such duration and intensity that each link has to pa.s.s over the threshold of our consciousness.

We have chains of material nerve processes to which eventually a link becomes attached that is attended with conscious perception. This is sufficiently established from the standpoint of the physiologist, and is also proved by our unconsciousness of many whole series of ideas and of the inferences we draw from them. If the soul is not to ship through the fingers of physiology, she must hold fast to the considerations suggested by our unconscious states. As far, however, as the investigations of the pure physicist are concerned, the unconscious and matter are one and the same thing, and the physiology of the unconscious is no "philosophy of the unconscious."

By far the greater number of our movements are the result of long and arduous practice. The harmonious cooperation of the separate muscles, the finely adjusted measure of partic.i.p.ation which each contributes to the working of the whole, must, as a rule, have been laboriously acquired, in respect of most of the movements that are necessary in order to effect it. How long does it not take each note to find its way from the eyes to the fingers of one who is beginning to learn the pianoforte; and, on the other hand, what an astonishing performance is the playing of the professional pianist. The sight of each note occasions the corresponding movement of the fingers with the speed of thought - a hurried glance at the page of music before him suffices to give rise to a whole series of harmonies; nay, when a melody has been long practised, it can be played even while the player's attention is being given to something of a perfectly different character over and above his music.

The will need now no longer wend its way to each individual finger before the desired movements can be extorted from it; no longer now does a sustained attention keep watch over the movements of each limb; the will need exercise a supervising control only. At the word of command the muscles become active, with a due regard to time and proportion, and go on working, so long as they are bidden to keep in their accustomed groove, while a slight hint on the part of the will, will indicate to them their further journey. How could all this be if every part of the central nerve system, by means of which movement is effected, were not able {74a} to reproduce whole series of vibrations, which at an earlier date required the constant and continuous partic.i.p.ation of consciousness, but which are now set in motion automatically on a mere touch, as it were, from consciousness - if it were not able to reproduce them the more quickly and easily in proportion to the frequency of the repet.i.tions - if, in fact, there was no power of recollecting earlier performances? Our perceptive faculties must have remained always at their lowest stage if we had been compelled to build up consciously every process from the details of the sensation-causing materials tendered to us by our senses; nor could our voluntary movements have got beyond the helplessness of the child, if the necessary impulses could only be imparted to every movement through effort of the will and conscious reproduction of all the corresponding ideas - if, in a word, the motor nerve system had not also its memory, {74b} though that memory is unperceived by ourselves. The power of this memory is what is called "the force of habit."

It seems, then, that we owe to memory almost all that we either have or are; that our ideas and conceptions are its work, and that our every perception, thought, and movement is derived from this source. Memory collects the countless phenomena of our existence into a single whole; and as our bodies would be scattered into the dust of their component atoms if they were not held together by the attraction of matter, so our consciousness would be broken up into as many fragments as we had lived seconds but for the binding and unifying force of memory.

We have already repeatedly seen that the reproductions of organic processes, brought about by means of the memory of the nervous system, enter but partly within the domain of consciousness, remaining unperceived in other and not less important respects. This is also confirmed by numerous facts in the life of that part of the nervous system which ministers almost exclusively to our unconscious life processes. For the memory of the so-called sympathetic ganglionic system is no less rich than that of the brain and spinal marrow, and a great part of the medical art consists in making wise use of the a.s.sistance thus afforded us.

To bring, however, this part of my observations to a close, I will take leave of the nervous system, and glance hurriedly at other phases of organised matter, where we meet with the same powers of reproduction, but in simpler guise.