A few months ago I was called in haste to see a patient, a large, strong man of one hundred and eighty pounds weight, who had been thrown down and trampled upon by his nineteen-year-oldson during an attack of somnambulism, and had received such serious injuries as to require immediate surgical aid. The next day this son came to consult me regarding his unfortunate habit of sleep-walking, which has often got him into trouble before, and has now resulted in serious injury to his father. He is a slight youth of one hundred and twenty pounds weight, light hair, gray eyes, and a bright, frank face, expressive of good health and good nature - "a perfect gentleman," as his father expressed it, "when himself, but ten men cannot manage him when he gets up in his sleep; he will do what he sets out to do."

Who would ever imagine that this slender, good-natured, gentlemanly lad, sooner than any other lad, would in his sleep develop somnambulism and a second personality, or that when it came that second personality should prove a stubborn Samson?

Little could Prof. Janet imagine that beneath the surface consciousness of that serene and stupid Leonie dwelt the frisky, vivacious, fun-loving Leontine, waiting only the magic key of hypnotism to unlock and bring her to the surface to reign instead of the heavy Leonie.

The people who, in various ways, develop second personalities may not differ, it seems, in any perceptible manner from other people; is it not quite possible, then, that other normal, ordinary people, possess a second personality, deep-down beneath their ordinary, everyday self, and that under conditions which favor a readjustment, this hidden subliminal self may emerge and become for a longer or a shorter time the conscious, acting one; and not only so, but may prove to be the brighter and better organized of the two?

Having now, as it were, a chart, imperfect though it be, of this outlying region, having some idea what to look for, and in what direction to look for it, it is possible that glimpses of this subliminal personality which each one unconsciously carries with him may be obtained under ordinary conditions and in everyday life, more frequently and more easily than we had imagined; for, as Ribot expresses it, the ordinary conscious personality is only a feeble portion of the whole psychical personality.

One example of this more usual form of double personality is afforded in ordinary dreaming. The dream country, like most of this outlying territory, has for the most part been studied without chart or compass. There is scarcely a point connected with the discussion of the subject upon which the most eminent authorities are not divided; it is Locke against Descartes, Hamilton against Locke, and Hobbes against the field.

If there be any one point, however, on which there is tolerable unanimity among all writers, ancient and modern, great and small, it is the absence in dreams of the normal acts and processes of volition, and, especially, of the faculty of attention. Now, this is exactly the condition which is conducive to the more or less perfect emergence and activity of the subliminal self, under whatever circumstances it occurs.

There is first, loss of consciousness from catalepsy, fright, depressing illness, hypnotism, or natural sleep, that is to say, the power of attention or volition in the primary self is abolished; then comes a readjustment of personalities, varying in completeness according to the ease with which, in different persons, this readjustment may be effected, and according to the completeness of the abolition of the power of attention and volition.

In sleep the conditions are favorable for this readjustment, and the subliminal self comes more or less perfectly to the surface; then appears that most peculiar and interesting series of pictures and visions which we call dreams; sometimes the rearranged, or rather unarranged, impressions and perceptions of the waking hours brought together, possibly just before the power of attention is entirely lost; sometimes the Puck-like work of the subliminal personality, the Leontines of the dream-country influencing the unconscious or semi-conscious primary self; sometimes the veridical or truth-telling dreams, which have been the wonder of all ages, and sometimes giving complete and active supremacy to the subliminal self as in natural somnambulism. Another portion of the field in which it might be profitable to look for evidence of the existence of a subliminal personality is in the eccentric work of genius ; and still another, in the unexpected and often heroic actions of seemingly ordinary persons under the stress and stimulus of a great emotion, as of joy, sorrow, or anger, or of intense excitement, as for instance, the soldier in battle, the fireman at the post of danger, or the philosopher or astronomer on the eve of a new discovery; in all these cases the ordinary personality with its intense self-consciousness and self-considering carefulness is submerged - it disappears - the power of voluntary attention to mental states or physical action is lost; a new and superior personality comes to the surface and takes control. The supreme moment passes, and the primary self resumes sway, scarcely conscious of what has been done or how it was accomplished; even sensation has been abolished, and it is only now that he discovers the bleeding bullet-wound, the charred member, or the broken bone.

In physical science, whenever some new fact or law or principle has been discovered, it is at once seen that many things which before were obscure, or perhaps could only be accounted for by a theory of chance, or of direct interference by an omnipotent Deity, are now illuminated by a new light, and order reigns where before only confusion and darkness were visible. Something of the same sort is beginning to be recognized in the world of mental and psychical phenomena. If the mathematical exactness which measured the force of gravity, or placed the sun in one of the foci of an ellipse instead of the centre of a circle cannot be applied here, it is only on account of the vast complexity of the problem presented, and of which we know so few of the elements.