48 PSYCHOLOGY higher phases J of it. Of late, however, the tendency has been to make consciousness cover all stages of mental development and all grades of presentation, so that a presentation of which there is no consciousness resolves itself into the manifest contradiction of an unpresented presentation a contradiction not involved in Leibnitz's " unapperceived perception." Moreover, the active form of the word "conscious" almost unavoidably suggests that an "uncon- scious mental modification " must be one in which that subjective activity, variously called consciousness, attention, or thinking, has no part. But such is not the meaning intended when it is said, for example, that a soldier in battle is often unconscious of his wounds or a scholar unconscious at any one time of most of the knowledge "hidden in the obscure recesses of his mind." There would be no point in saying a subject is not conscious of objects that are not presented at all ; but to^say that what is presented lacks the intensity requisite in the given distribution of attention to change that distribution appreciably is pertinent enough. Sub- conscious presentations may tell on conscious life as sunshine or mist tells on a landscape or the underlying writing on a palimpsest although lacking either the differences of intensity or the indivi- dual distinctness requisite to make them definite features. Even if there were no facts to warrant this conception of a subliminal presentation of impressions and ideas it might still claim an a priori justification. For to assume that there can be no presentations save such as pertain to the complete and perfect consciousness of a human being is as arbitrary and as improbable as it would be to suppose in the absence of evidence to the contrary that there was no vision or audition save such as is mediated by human eyes and ears. Psychological magnification is not more absurd than physical, although the processes in the two cases must be materially different ; but of course in no case is magnification possible with- out limit. The point is that, while we cannot fix the limit at which the subconscious becomes the absolutely unconscious, it is only reasonable to expect beforehand that this limit is not just where our powers of discrimination cease. Over and above hindrances to its acceptance which may be set down to the paradoxical and inaccurate use of the word uncon- sciousness, there are two material difficulties which prevent this hypothesis from finding favour. First, the prevailingly objective implications of language are apt to make us assume that, as a tree remains the same tiling whether it is in the foreground of a land- scape or is lost in the grey distance, so a presentation must be a something which is in itself the same whether above the threshold of consciousness or below, if it exist, that is, in this lower degree at all. But it must be remembered that we are not now dealing with physical things but with presentations, and that to these the Berkeleyan dictum applies that their esse is percipi, provided, of course, we give to percipi the wide meaning now assigned to consciousness. The qualitative differences of all presentations and the distinctness of structure of such as are complex both diminish with a diminution of intensity. In this sense much is latent or "involved" in presentations lying below the threshold of con- sciousness that becomes patent or "evolved" as they rise above it. But, on the other hand, the hypothesis of subconsciousness does not commit us to the assumption that all presentations are by their very nature imperishable : while many modifications of con- sciousness sink only into obliviscence, many, we may well suppose, lapse into complete oblivion and from that there is no recall. Secondly, to any one addicted to the atomistic view of presenta- tions just now referred to it may well seem 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 can be in any sense present continuously. The brunt of such an objection is effectually met by the fact that the same presentation 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 a language by its vocabulary, nor may we equate the extent of our spiritual treasures as successively unfolded with the psychical apparatus, so to say, into which they resolve. 2 The attempt has more than once been made to avoid the diffi- culties besetting subconsciousness by falling back on the concep- tions of faculties, capacities, or dispositions. Stored-up knowledge, says J. S. Mill, " is not a mental state but a capability of being put into a mental state" ; similarly of the cases which Hamilton records, " in which the extinct memory [?] of whole languages was suddenly restored," he says, " it is not the mental impressions that are latent 1 The following brief passage from his Principe* de la Nature et de la Grace ( 4) shows his meaning : " II est bon de faire distinction entre la Perception, qui est 1'etat interieur de la Monade representant les choses externes, et V Ap- perception, qui est la Conscience, ou la connoissancc reflexive de cet etat interieur, laquelle n'est point dpnne'e 4 toutes les ames, ni toujours a la mfme &me. Et Jipte 2 Much light may be thrown on this matter and on many others by such inquiries as those undertaken by Mr Francis Gallon, and described in his Inquiries into Human Faculty, pp. 1S2-203. but the power of reproducing them." But surely the capability of being put into a mental state is itself a mental state and something actual, and is, moreover, a different something when the state to be reproduced is different. If not, how is such capability ever exerted ? Even where the capability cannot be consciously exerted, must there not still be something actual to justify the phrase latent power ? The " exaltation " of delirium may account for the intensi- fication but not for the contents of the "extinct memories" which its unwonted glow reveals. It seems extraordinary that Mill of all men, and in psychology of all subjects, should have supposed such merely formal conveniences as these conceptions of faculties and powers could ever dispense us from further inquiry. It might be urged in Mill's defence that he Juis investigated further and concludes that the only distinct meaning he can attach to uncon- scious mental modification is that of unconscious modification of the nerves a modification of the nerves, that is to say, without any psychical accompaniment. But, while we can frequently under- stand a psychical fact better if we can understand its physical counterpart, a physiological explanation can never take the place of a psychological explanation. If all we have to deal with are nervous modifications which have no psychical concomitants, then so far there is nothing psychological to explain ; but, if there really is anything calling for psychological explanation and this Mill does not deny then physical accompaniments must admit of psychical interpretation if they are to be of any avail. And in fact, although Mill professes to recognize only unconscious modi- fications of nerves, he finds a psychological meaning for these by means of his "mental chemistry," a doctrine which has done its work and which we need not here discuss. The exposition of subconsciousness given by Wundt is in the main an advance on that of Mill and calls for brief notice. Pre- sentations, says Wundt, 3 are not substances but functions, whose physiological counterparts in like manner are functional activities, viz. , of certain arrangements of nerve-cells. Consciousness of the presentation and the nervous activity cease together, but the latter leaves behind it a molecular modification of the nervous structure which becomes more and more permanent with exercise, and is such as to facilitate the recurrence of the same functional activity. A more precise account of these after-effects of exercise is for the present unattainable ; nevertheless Wundt regards it as obvious that they are no more to be compared to the activity to which they predispose than the molecular arrangement of chlorine and nitrogen in nitric chloride is to be compared to the explosive decomposition that ensues if the chloride is slightly disturbed. Mutatis mutandis, on the psychological side the only actual pre- sentations are those which we are conscious of as such ; but pre- sentations that vanish out of consciousness leave behind psychical dispositions tending to renew them. The essential difference is that, whereas we may some day know the nature of the physical disposition, that of the psychical disposition must of necessity be for ever unknown, for the threshold of consciousness is also the limit of internal experience. The theory thus briefly summarized seems in some respects arbitrary, in some respects ambiguous. It is questionable, for instance, whether the extremely meagre in- formation that physiologists at present possess at all compels us to assume that the " physical disposition " of Wuudt cannot con- sist in a continuous but much fainter discharge of function. At all events it is quite beside the mark to urge, as he does, that the effect of training a group of muscles is not shown in the persist- ence of slight movements during intervals of apparent rest. 4 The absence of molar motions is no evidence of the absence of molecular motions. And it is certain that psychologically we can be conscious of the idea of a movement without the movement actually ensuing, yet only iu 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, and if this amount of activity is possible without movement why may not a much less amount be conceived possible too ? Again, what meaning can possibly be attached to a psychical disposition which is the counterpart, not of physical changes, but of an arrangement of molecules ? Compared with such an inconceivable unknown, the perfectly conceivable hypothesis of infinitesimal presentations so faint as to elude discrimination is every way preferable. In fact, if conceivability is to count for any- thing, we have, according to Wundt, no choice, for "we can never think of a presentation that has disappeared from consciousness except as retaining the properties it had when in consciousness." None the less he holds it to be an error " to apply to presentations themselves a style of conception that has resulted from our being of necessity confined to consciousness." Verily, this is phenomenalism with a vengeance, as if presentations themselves were not also confined to consciousness ! 3 Physiologisfhe Psychologic, p. 203 sq. < J. 8. Mill adopts substantially the same line of argument : " 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 " (Examination of Sir W. Hamilton's Philosophy, 3d ed., p. 329).
