Bearing these analogies in mind, we shall see that the development of somnambulism out of ordinary dream is no isolated oddity. It is parallel to the development of a secondary state from _idées fixes_ when these have passed a certain pitch of intensity. The sleep-waking states which develop from sleep have the characteristics which we should expect from their largely subliminal origin. They are less coherent than waking secondary personalities, but richer in supernormal faculty. It is in connection with displays of such faculty--hyperæsthesia or telæsthesia--that they have been mainly observed, and that I shall, in a future chapter, have most need to deal with them. But there is also great interest simply in observing what fraction of the sleep-waker's personality is able to hold intercourse with other minds. A trivial instance of such intercourse reduced to its lowest point has often recurred to me. When I was a boy another boy sleeping in the same room began to talk in his sleep. To some slight extent he could answer me; and the names and other words uttered--_Harry, the boat_, etc.--were appropriate to the day's incidents, and would have been enough to prove to me, had I not otherwise known, who the boy was. But his few coherent remarks represented not facts but dreaming fancies--_the boat is waiting_, and so forth. This trivial jumble, I say, has since recurred to me as precisely parallel to many communications professing to come from disembodied spirits. There are other explanations, no doubt, but one explanation of such incoherent utterances would be that the spirit was speaking under conditions resembling those in which this sleeping boy spoke. There are, of course, many stages above this. Spontaneous somnambulistic states become longer in duration, more coherent in content, and may gradually merge, as in the well-known case of Félida X. (see Appendix II. C) into a continuous or dimorphic new personality. The transition which has now to be made is a very decided one. We have been dealing with a class of secondary personalities consisting of elements _emotionally selected_ from the total or primary personality. We have seen some special group of feelings grow to morbid intensity, until at last it dominates the sufferer's mental being, either fitfully or continuously, but to such an extent that he is "a changed person," not precisely insane, but quite other than he was when in normal mental health. In such cases the new personality is of course dyed in the morbid emotion. It is a kind of dramatic impersonation, say, of jealousy, or of fear, like the case of "demoniacal possession," quoted from Dr. Janet in Appendix II. B. In other respects the severance between the new and the old self is not very profound. Dissociations of memory, for instance, are seldom beyond the reach of hypnotic suggestion. The cleavage has not gone down to the depths of the psychical being.