It seems, therefore,—and the analogy of dreams points in this direction also,—that our moral nature is as easily split up as our intellectual nature, and that we cannot be any more certain that the minor current of personality which is diverted into some new channel will retain moral than that it will retain intellectual coherence.

To return once more to the Chinese devil-possessions. Dr. Nevius asserts, though without adducing definite proof, that the possessing devils sometimes showed supernormal knowledge. This is a better argument for their separate existence than their fiendish temper is; but it is not in itself enough. The knowledge does not seem to have been specially appropriate to the supposed informing spirit. It seems as though it may have depended upon heightened memory, with possibly some slight telepathic or telæsthetic perception. Heightened memory is thoroughly characteristic of some hysterical phases; and even the possible traces of telepathy (although far the most important feature of the phenomena, if they really occurred) are, as we have seen, not unknown in trance states (like Léonie's) where there is no indication of an invading spirit.

Temporary control of the organism by a widely divergent fragment of the personality, self-suggested in some dream-like manner into hostility to the main mass of the personality, and perhaps better able than that normal personality to reach and manipulate certain stored impressions,—or even certain supernormal influences,—such will be the formula to which we shall reduce the invading Chinese devil, as described by Dr. Nevius,—and probably the great majority of supposed devil-possessions of similar type.

The great majority, no doubt, but perhaps not all. It would indeed be matter for surprise if such trance-phenomena as those of Mrs. Piper and other modern cases had appeared in the world without previous parallel. Much more probable is it that similar phenomena have occurred sporadically from the earliest times,—although men have not had enough of training to analyse them.

And, in fact, among the endless descriptions of trance-phenomena with which travellers furnish us, there are many which include points so concordant with our recent observations that we cannot but attach some weight to coincidences so wholly undesigned.[199] But although this may be admitted, I still maintain that the only invaders of the organism who have as yet made good their title have been human, and have been friendly; and with this clearance should, I think, vanish the somewhat grim associations which have gathered around the word possession.

Assuming, then, as I think we at present may assume, that we have to deal only with spirits who have been men like ourselves, and who are still animated by much the same motives as those which influence us, we may briefly consider, on similar analogical grounds, what range of spirits are likely to be able to affect us, and what difficulties they are likely to find in doing so. Of course, actual experience alone can decide this; but nevertheless our expectations may be usefully modified if we reflect beforehand how far such changes of personality as we already know can suggest to us the limits of these profounder substitutions.

What, to begin with, do we find to be the case as to addition of faculty in alternating states? How far do such changes bring with them unfamiliar powers?

Reference to the recorded cases will show us that existing faculty may be greatly quickened and exalted. There may be an increase both in actual perception and in power of remembering or reproducing what has once been perceived. There may be increased control over muscular action,—as shown, for instance, in improved billiard-playing,—in the secondary state. But there is little evidence of the acquisition—telepathy apart—of any actual mass of fresh knowledge,—such as a new language, or a stage of mathematical knowledge unreached before. We shall not therefore be justified by analogy in expecting that an external spirit controlling an organism will be able easily to modify it in such a way as to produce speech in a language previously unknown. The brain is used as something between a typewriter and a calculating machine. German words, for instance, are not mere combinations of letters, but specific formulæ; they can only seldom and with great difficulty be got out of a machine which has not been previously fashioned for their production.

Consider, again, the analogies as to memory. In the case of alternations of personality, memory fails and changes in what seems a quite capricious way. The gaps which then occur recall (as I have said) the ecmnesia or blank unrecollected spaces which follow upon accidents to the head, or upon crises of fever, when all memories that belong to a particular person or to a particular period of life are clean wiped out, other memories remaining intact. Compare, again, the memory of waking life which we retain in dream. This too is absolutely capricious;—I may forget my own name in a dream, and yet remember perfectly the kind of chairs in my dining-room. Or I may remember the chairs, but locate them in some one else's house. No one can predict the kind of confusion which may occur.

We have also the parallel of somnambulic utterance. In talking with a somnambulist, be the somnambulism natural or induced, we find it hard to get into continuous colloquy on our own subjects. To begin with, he probably will not speak continuously for long together. He drops back into a state in which he cannot express himself at all. And when he does talk, he is apt to talk only on his own subjects;—to follow out his own train of ideas,—interrupted rather than influenced by what we say to him. The difference of state between waking and sleep is in many ways hard to bridge over.