that supraliminal current of consciousness which we habitually identify with ourselves1."

It may be seen that the ambiguity, already referred to, pertaining to the use of the word consciousness, follows us here if we try to be clear about the locus of the threshold. In the first part of Myers' definition he is obviously referring to a threshold which lies between what is in consciousness and what is out of consciousness at the moment; but in the latter part the threshold seems to separate that part of the mind which is capable of becoming conscious from a part which ordinarily has no such power. It is a threshold between the self that each of us knows by introspection, and a hidden self of which we have no direct cognisance.

Between what is conscious at the moment and what is unconscious or subliminal at the moment there is a clear distinction, and it would seem to be urgently necessary to distinguish also between that part of the subliminal which is capable of entering consciousness and the part which is not capable of doing so. Such a distinction has been drawn by Freud. That part of the mind which is out of consciousness at the moment, but is capable of entering into it-the memories of every kind which we have at our disposal-he calls the Preconscious. That part of the mind which is out of consciousness at the moment and is incapable of entering into it under any ordinary circumstances, he calls the Unconscious 'proper.' Preconscious ideas are latent because for the time being their activity is slight; they are too feeble to step over the threshold of consciousness. But, when they become strong, they overstep the threshold and enter the conscious field. Freud maintains, however, that some ideas, namely, those that are repressed, cannot enter into consciousness, no matter how strong and active they may be. Such ideas he calls Unconscious in the technical sense of the word.

It is perhaps unfortunate that Freud uses the word unconscious both in the descriptive sense of being out of consciousness at the moment, thereby making it include the preconscious, and also in the particular technical sense of the Unconscious proper-the unconscious constituted by repression. This double usage tends to set up a confusion similar to that which accrued from the old custom of using the word consciousness so as to include within it what we now call the preconscious, as well as what we may call the conscious 'proper.' Nevertheless Freud's division of mental contents into conscious, preconscious and unconscious makes for clearness and precision when we attempt to give a regional or topographical description of the structure of the mind.

1 Human Personality, Vol. I. p. 14.

It is not, however, in a descriptive sense only that Freud employs these terms. He uses them also in a 'systematic' sense which is even more significant for his psychological theories. He conceives of the mind as a reflex system-a mental reflex arc-sensory or receptive at one end, and motor or executive at the other. Any stimulus applied at the receptive end sets up a movement which tends to spread to the motor end. The setting up of this movement, the initiation of any mental process, is accompanied by release of psychical energy, the accumulation of which is experienced as discomfort; and the goal of the activity set up is to effect the discharge of this energy and thereby to bring the system to a condition of rest again. The state of excitation, which is experienced as discomfort, is thus changed to a state of relief which is experienced as pleasure, and the tendency within the mind to effect this change is what Freud calls a 'wish.' The chief characteristic of such a mental system is the freedom with which it permits the psychical impulse to spread through all its parts in search, as it were, for some outlet for the discharge. When this is achieved, pleasure is experienced, so that the purpose of the movement may be said to be the pursuit of pleasure; the system is actuated by what Freud calls. the 'pleasure-principle.'

At first the tendency of a movement set up within the system is to regress to the sensory end of the mental arc, thereby affording hallucinatory gratification through revival of the sensations which had accompanied previous gratifications. But very soon this is found to be unsuitable to the demands of the 'real' world, and a secondary mental system arises, or comes into action, which secures the inhibition of the tendency to regression, and directs the impulses towards the motor end of the mental arc so as to bring about, by action upon the external world, the changes necessary for the production of a real gratification instead of an imaginary one. The activity of this secondary system is guided by what Freud calls the 'reality-principle' in contradistinction to the pleasure-principle underlying the activities of the primary system.

The secondary system does but control and guide the energies of the primary system so as to secure more adequately the gratifications which the primary system strives for, but achieves only imperfectly because of its want of conformity to reality. So long as they are in agreement as to what is pleasant and what is unpleasant they work harmoniously together. But a time comes when disagreement sets in. With the development of the child's personality it comes to pass that what causes pleasure in the primary system causes pain in the secondary

system. The task of the secondary system here is no longer to control and guide the tendencies of the primary system towards a real fulfilment of its wishes. The wishes of the two systems are not now the same. The tendencies which give pleasure to the primary system give pain to the secondary system, and the secondary system tries only to avoid these tendencies and get away from them. Thus arises a divorce between the two systems which results in the establishment of the mechanism of repression, and the formation of the two mental systems which we call the unconscious and the preconscious.

The primary and secondary systems are thus the fore-runners of the unconscious and the preconscious. The unconscious retains all the characteristics of the primary system. It is guided solely by the pleasure principle; it can do nothing but wish, and in the pursuit of the gratification of its wishes the freest possible movement of the psychic impulse is permitted, just as in the primary system. And just as the secondary system does not always succeed in mastering the tendency to regression, so the preconscious is ever at war with the unconscious, and sometimes becomes subject to its domination. It is the conflict between them which gives rise to the mechanism of repression, and the earliest repressions thus brought about form the core of the unconscious throughout life.

The whole of the content of the mind would seem to be divided by Freud into that which, in the systematic sense, is preconscious and that which is unconscious. The content of consciousness is really part of the preconscious system. Consciousness itself he compares to a sense-organ which perceives certain processes set up in the preconscious. Some of Freud's disciples seem to suppose that Freud was the first to make the comparison of consciousness to a sense-organ, but it is really a very old notion in psychology. A very similar view may be found in the writings of the Scottish school of philosophers and of their French followers at the beginning of the nineteenth century. Royer Collard, for example, held that "our sensations, acts, thoughts, pass before our consciousness as the waters of a river under the eye of a spectator on its banks." Consciousness has also been compared to a stage on which plays are acted, but this simile would apply better to that part of the preconscious of which consciousness is the spectator.

Whether or not the comparison of consciousness to a sense-organ is legitimate, it is useful in that it emphasises the fact that neither the contents nor the processes of consciousness have any peculiar characteristics other than those that belong to the preconscious. The preconscious contents are just those that are qualified to enter consciousness,

and conscious process and preconscious process have been one from the beginning. On the other hand, the contents of the unconscious are just those contents of the mind which are disqualified from entering consciousness in undisguised form, and unconscious process has been different from preconscious process from the beginning.

Freud does not often use the metaphor of a threshold in delimiting the different regions of the mind, but just as we speak of a threshold between the conscious and the preconscious, so we may say there is a threshold between the preconscious and the unconscious, but this threshold has a barrier. The doorway here is not freely open to every idea that is strong enough to overstep the threshold. There appears to be a doorkeeper the Freudian 'censor'-who discriminates between the applicants, and selects those that may be admitted into the preconscious. The censor has behind him all the repressing forces which keep out of the preconscious those ideas that would be unbearable if they became conscious.

The unconscious due to repression is the true Unconscious of Freudian psychology. It is that part of the mind which retains the characteristics of the primary system, is guided by the pleasure principle and is under repression. The preconscious is that part of the mind which retains the characteristics of the secondary system, is guided by the reality principle, and is the source of the repressing forces.

This is the systematic meaning of the term unconscious which, in its descriptive meaning of being merely 'out of consciousness' includes the preconscious. To say that a thought or mental process is unconscious should, in psycho-analytic writings, be held to imply that it belongs to that mental system whose mode of functioning corresponds to what Freud calls the primary process; but it cannot be said that authors have adhered to this usage, or that the context always makes it clear when it is used in the descriptive and when in the systematic sense.

A further source of confusion is found in the fact that certain preconscious contents which form associative connections with unconscious contents are subject to repressing forces; their emergence into consciousness is met with resistance, and they are therefore, in the systematic sense, unconscious. Freud provides for them a second censor which he places between the conscious and the preconscious.

Freud's explanation of the origin of the Unconscious accords well with the nature of its contents and processes which he discovered by the technical methods of Psycho-Analysis. We are prepared to find that the Unconscious consists essentially of just those tendencies or

wishes whose satisfaction gives pleasure to the child, but are reprehensible or painful to the adult. And this is indeed the teaching of Psycho-Analysis. The Unconscious is just the infantile mind, persisting throughout life, covered over, as it were, by the adult mind which has developed in response to the claims of reality. Moreover, this infantile part of the mind is not wholly derived from the childhood of the individual; it is partly derived from the childhood of the race. And some of the tendencies derived from this latter source have never entered consciousness at all, but have been under repression from the beginning. Of the same nature are the emotional reactions which arise when the change in the affective values of the primitive tendencies supervenes. We must believe that the readiness so to react is an inherited function of the preconscious, and that its emergence in the child is part of the recapitulation of racial history and marks the period of man's transition from the brute to the human.

If all psychologists accepted Freud's conclusions as to the origin and nature of the unconscious there would be little room for ambiguity in the terms used to delimit the different regions of the mind. Indeed, if all those who more or less consistently use his technical methods and base their conceptions on the results of mental analysis, could have adhered to his nomenclature so far as it served their purpose, we should have been saved some of the difficulties which beset our path when we try to correlate the findings of the different schools.

The Zürich school of Analytical Psychology founded by Jung is an offshoot from the psycho-analytic school of Freud; but, as is well known, Jung has in recent years diverged in several directions from the psychoanalytic stand-point. One of the most important of these divergences concerns the nature and origin of the unconscious.

Jung defines the unconscious as "the totality of all psychic phenomena that lack the quality of consciousness." He says that instead of being called unconscious, these phenomena may equally well be called subliminal a term which, in his view, presupposes the hypothesis that each psychic content must possess a certain energic value in order that it may become conscious. Such an admission would seem to imply that, in Jung's view, every content of the unconscious is unconscious because it has not sufficient energic value or intensity to overstep the threshold. This would exclude the whole of the true unconscious of Freud, because an essential characteristic of a psychic content that is unconscious in the 'proper' Freudian sense, is that it cannot enter consciousness simply in virtue of its strength or activity. Yet Jung