The unreasonable fears and obsessions of the 'shell-shocked' soldier rest upon causes of which he is unaware, and the burnt child dreads the fire even if he were too young to remember the burning. The chicken that has once tasted a nauseous caterpillar will ever after avoid its like, but we only know that a certain emotion is called up by the sight of the caterpillar which causes the chicken to abstain; it is an unnecessary assumption that memory, as we know it, is concerned. The obsession of the soldier who felt that he must attack his companion (see Chapter VIII) arose from the unconscious, and those animal actions which we attribute to memory can similarly have their origins apart from consciousness.
McDougall's definition of instinct applies very well to obsessions, except that the latter are not innate but acquired; that one definition should apply to both groups is due to them all having their origin in the unconscious.
Man, though urged by the instincts and memories of his unconscious, yet lives in his stream of consciousness and tends to believe that there is no other mind-work involved in his thoughts and actions; but as the latest evolved function is the most variable and unstable so man's consciousness is his most uncertain function, its chief variability being in the extent to which it controls or is controlled by the unconscious.
The ideal human mind would be perfectly integrated, there would be no logic-tight compartments, all its complexes would be apparent to the consciousness, all memories available when needed, all emotions assigned to their proper cause and all instincts recognised and well-directed; and the owner of it would find life in our world intolerable.
Remote from this ideal is the mind whose unconscious has taken the place, wholly or in part, of the stream of consciousness. Perhaps the consciousness has not developed—then we find idiocy or imbecility; perhaps some distorted emotion from the unconscious has been the source of a dissociated stream of ideas which becomes predominant and brings its owner within the legal definition of a lunatic.
Between the extremes are the rest of mankind, the matter-of-fact man who reconciles himself to his world by a few serviceable logic-tight compartments, the man of temperament—artist, poet, or tramp—who counts the emotions arising from the unconscious as among the real things of life, and the other people of temperament who, finding their emotions and desires in discord with their surroundings, misdirect them and join the sufferers whom we call neurotic.
Then there are those who build up from the unconscious a fantastic world of imaginings, and, knowing nothing of the source, attribute them to outside intelligences or beings like themselves. To these belong the seers and mystics and their present-day representatives, the mediums, clairvoyants, and other believers in their own fantasies.
The counterpart of the medium is the ready believer, and each is reciprocally the victim of the other.
The medium has his dissociated stream with its hyperæsthesia and receptivity—alert to pick up the slightest hint and cast it back as a spirit revelation, and ready, moreover, to use more material trickery if needful. On the side of the believer is a logic-tight compartment containing his readiness to seize upon the feeblest evidence of the supernatural. How far he progresses into a dissociation one cannot tell, but when two Dissociates apparently bearing the stamp of honesty—one the medium and one the believer—work into each other's hands results may well be such as to defy explanation.
The study of the unconscious is legitimate, and if one chooses knowingly to tap its stores by a method of dissociation some increase of knowledge (not about the supernatural, but about the ways of the human mind) may be expected.