Every one is familiar with the phenomenon of occasional loss of memory. Men are constantly losing consciousness, from disease, violence, or violent emotion, and emerging again into active life with a gap in their memory. Nay, every night we become unconscious in sleep, and rarely, if ever, remember anything that we think of during slumber. Sometimes in rare cases there is a distinct memory of all that passes in the sleeping and the waking states, and we have read of one young man whose sleeping consciousness was so continuous that he led, to all intents and purposes, two lives. When he slept he resumed his dream existence at the point when he waked, just as we resume our consciousness at the point when we fall asleep. It was just as real to him as the life which he lived when awake. It was actual, progressive, continuous, but entirely different, holding no relation whatever to his waking life. Of his two existences he preferred that which was spent in sleep, as more vivid, more varied, and more pleasurable. This was no doubt an extreme and very unusual case. But it is not impossible to conceive the possibility of a continuous series of connected dreams, which would result in giving us a realizing sense of leading two existences. That we fail to realize this now is due to the fact that our memory is practically inert or non-existent during sleep. The part of our mind which dreams seldom registers its impressions in regions to which on waking our conscious personality has access.
The conception of a dual or even a multiple personality is worked out in a series of papers by Mr. F. W. H. Myers[1], to which I refer all those who wish to make a serious study of this novel and startling hypothesis. But I may at least attempt to explain the theory, and to give some outline of the evidence on which it is based.
[1] "Human Personality" (Longmans, Green & Co.)
If I were free to use the simplest illustration without any pretence at scientific exactitude, I should say that the new theory supposes that there are inside each of us not one personality but two, and that these two correspond to husband and wife. There is the Conscious Personality, which stands for the husband. It is vigorous, alert, active, positive, monopolising all the means of communication and production. So intense is its consciousness that it ignores the very existence of its partner, excepting as a mere appendage and convenience to itself. Then there is the Unconscious Personality, which corresponds to the wife who keeps cupboard and storehouse, and the old stocking which treasures up the accumulated wealth of impressions acquired by the Conscious Personality, but who is never able to assert any right to anything, or to the use of sense or limb except when her lord and master is asleep or entranced. When the Conscious Personality has acquired any habit or faculty so completely that it becomes instinctive, it is handed on to the Unconscious Personality to keep and use, the Conscious Ego giving it no longer any attention. Deprived, like the wife in countries where the subjection of woman is the universal law, of all right to an independent existence, or to the use of the senses or of the limbs, the Unconscious Personality has discovered ways and means of communicating other than through the recognised organs of sense.