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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 familiarize 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 space 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. 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 pass 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 slip through the fingers of physiology, she must hold fast to the considerations suggested by

See quotation from Bonnet, p. 59 of this volume. By “preserving the memory of habitual actions " Professor Hering probably means, retains for a long while and repeats motion of a certain character when such motion has been once communicated to it.

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 co-operation of the separate muscles, the finely adjusted measure of participation 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 perfe&ly 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 1 to reproduce whole series of vibrations, which at an earlier date required the constant and continuous participation 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 repetitions, if, in fa&t, 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 sensationcausing 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, 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

It should not be “if the central nerve system were not able to reproduce whole series of vibrations," but“ if whole series of vibrations do not persist though unperceived," if Professor Hering intends what I suppose him to intend.

Memory was in full operation for so long a time before any. thing like what we call a nervous system can be dete&ed, that Professor Hering must not be supposed to be intending to confine memory to a motor nerve system. His words do not even imply that he does, but it is as well to be on one's guard.

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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 assistance 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 organized matter, where we meet with the same powers of reproduction, but in simpler guise. Daily experience teaches us that a muscle becomes the

a stronger the more we use it. The muscular fibre, which in the first instance may have answered but feebly to the stimulus conducted to it by the motor nerve, does so with the greater energy the more often it is stimulated, provided, of course, that reasonable times are allowed for repose. After each individual action it becomes more capable, more disposed towards the same kind of work, and has a greater aptitude for repetition of the same organic processes. It gains also in weight, for it assimilates more matter than when constantly at rest. We have here, in its simplest form, and in a phase which comes home most closely to the comprehension of the

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