this concept of an ultra-liminal presentation of impressions it might still claim an a priori justification.
The subconscious presentation of ideas as distinct from impressions calls, however, for some special consideration. As we S be can turn our attention to the sensory threshold sgougdeas and await the entrance of an expected impression, so we may await the emergence of a “memory image ”; and again the threshold turns out to be not a mathematically exact boundary but a region of varying depth.1 What we are trying to recollect seems first to waver, now at the tip of our tongue and the next moment completely gone, then perhaps a moment afterwards rising into clear consciousness. Sometimes when asked, say, for the name of a, certain college contemporary we reply: I cannot tell, but I should know the name if I heard it. We are aware that we could “ recognize, ” though we cannot “ reproduce. ” At other times we are confident that even recognition is no longer possible, and still if we met the man himself in the old scenes and heard his voice his name might yet recur. Nevertheless, it may be urged, it is surely incredible that all the incidents of a long lifetime and all the items of knowledge of a well-stored mind that may possibly recur-“ the infinitely greater part of our spiritual treasures, ” as Hamilton says-are severally retained and continuously presented in the form and order in which they were originally experienced or acquired. This, however, is not implied. Images in contrast to impressions have always a certain generality. The same image may figure in very various connexions, as may the same letter, for example, in many words, the same word in many sentences. We cannot measure the literature of language by its vocabulary, nor may we equate the extent of our “ spiritual treasures ” when these are successively unfolded with the psychical apparatus, so to say, in which they are subconsciously involved.” Take the first book of the Aeneid, which, as Macaulay would say, every schoolboy knows: as subconsciously involved, when the boy is not thinking of it, his knowledge is more comparable to a concordance than to the text itself, which nevertheless can be reproduced from it. In the text Aeneas occurs many times, in the concordance as a heading but once. But give him the cue Aeneas scopnlnm, and the boy reels off from the 180th line; or Praecipue pins Aeneas, and he starts with the 220th. But ask him for the 580th line; he is probably helpless, while a dunce with the book in his hand can read it off at once. Say instead Et pater Aeneas, and the boy can straightway complete the line while the dunce is now helpless. So though its explicit revival is successional, occurs, so to say, in single file, a whole scheme in which many ideas are involved may rise towards the threshold together. When our schoolboy, for example, turns from classics to geography, the mention of Atlas, which might then have recalled a Titan, now leads him to think only of his book of maps. And there is a like sudden shifting of the substratum of our thoughts, when, taking up the morning paper, we glance first at the foreign telegrams, then at the money market, and then at the doings of our political friends. Yet more remote than all, obscurer but more pervasive, like the clouds of Cherubs or imps vaguely limned in medieval pictures, are the indefinite constituents of our emotional atmosphere, “gay motes that people the sunbeams ” of our cheerfulness and make all couleur de rose, or “ horrid shapes and sights unholy ” that overcast the outlook when we “ have the blues.” And as attention relaxes, these advance into the foreground and become more or less palpable hopes or fears. 1 Herbart and Fechner describe subconscious presentations generally as existing below the threshold. On the other hand, we have spoken of subconscious sensations as existing beyond it. In view of the important differences between the two forms of presentations primary and secondary, this distinction of ultra-liminal and subliminal seems convenient and justifiable.
This doctrine of the involution and evolution of ideas we owe to Leibnitz. Herbart attempted in a very arbitrary and a priori fashion to develop it into a physical statics and dynamics with the result-usual to extreme views-that later psychologists neglected it altogether. There are now signs of a fresh reaction, and we shall continually come across evidence of the wide range 'and great importance of the doctrine as we proceed.
Because of the manifold forms into which they may evolve, subconscious images, while still involved, are sometimes called “ psychical ” or more definitely “ presentational dispositions.” The word disposition means primarily an arrangement, as when we talk of the disposition of troops in a battle or of cards in a game; the disposita, that is to say, are always something actual. Which of several potential dispositions they will actually assume will depend upon circumstances, but at least, as Leibnitz long ago maintained, “les puissances véritables ne sont jamais des simples possibilités.” What is requisite to the realization of a given potentiality is sometimes a condition to be added, sometimes it is one to be taken away. A locomotive with the fire out has no tendency to move, but with steam up it is only hindered from moving by the closure of the throttle-valve or the friction of the brake. Now presentational dispositions we assume to be of the latter sort. They are processes or functions more or less inhibited, and the inhibition is determined by their relation to other psychical processes or functions. The analysis and genesis of these presentational interactions will occupy us at length by and by; it may then be possible to explain the gradual involution of what was successively unfolded in explicit consciousness into those combinations which Herbart called “ apperception-masses, ” combinations devoid of the concrete hints of date and place which are essential to memory. Meanwhile the evidence adduced-decidedly cogent though admittedly indirect-together with the difficulties besetting the extreme view that beyond or below the threshold of consciousness there is nothing presentational, seems clearly to justify the hypothesis of subconsciousness. At the same time the principle of continuity, everywhere of fundamental importance when we are dealing with reality, forbids the attempt arbitrarily to assign any limits to the subconscious.-Many psychologists have proposed to explain subconscious retention by habit. But it is obvious that habit itself implies retention and is practically synonymous with disposition; it must therefore presuppose disposita if we are to escape the absurdities of puissances on facnltés nnes, with which in this very Connexion Leibnitz twitted Locke. Yet, obvious as all this may be, it is frequently ignored even by those who are fond of exposing the pretended explanations of the “ faculty-psychologists ” and quoting Moliére to confute them. Thus we find J. S. Mill arguing: “ I have the power to walk across the room though I am sitting in my chair; but we should hardly call this power a latent act of walking.” Nor should we call it a power at all if Mill had been paralysed, or if, instead of sitting in his chair, he had been lying in his cradle. What we want is the simplest psychological description of the situation after the power has been acquired by practice and is still retained. In such a case we can be conscious of the “ idea ” of the movement without the movement actually ensuing; yet only in such wise that the idea is more apt to pass over into action the intenser it is, and often actually passes over in spite of us. Surely there must be some functional activity answering to this conscious presentation; why may not a much less amount of it be conceived possible in subconscious presentation? Sensation, Movement and the External World.
16. On the view of experience here maintained, we are bound to challenge the description of sensations* as due to physical stimuli-widely current though it is-as one that is psychologically inappropriate. The ggggizf; 0 following definition, given by Bain, may be 'taken as a type: “ By sensations, in the strict meaning, we understand the mental impressions, feelings or states of consciousness following on the action of external things on some part of the body, called on that account sensitive.” 5 It is true, no doubt, that what the psychologist calls sensibility has as its invariable concomitant what physiologists call sensibility, 3 Examination of Sir W. Hamilton's Philosophy, 3rd ed., p. 329. 4 For a detailed account of the various sensations and perceptions pertaining to the several senses the reader is referred to the articles VISION; HEARING; TOUCH; TAsrE; SMELL, &c.
5 Senses and Intellect, 4th ed. (1894), p. 101.