We have learned in the preceding* chapters that the phenomena of hypnosis are extremely complex, and the question now is, "Can these phenomena be explained?" We must not demand too much in this connection. To explain a hitherto unknown thing, we must trace it back to what we do know. If we adhere to that, and also bear in mind that we know nothing of the real nature of our mental processes, it is evident that any explanation of hypnosis must be a limited one. Our knowledge of mental processes is confined to certain concomitant phenomena and their symptoms, and these are often but inadequately apprehended, while the real nature of such processes is debarred us. Under these circumstances we must be satisfied by such an explanation as may be got by demonstrating that hypnosis presents phenomena parallel to those of non-hypnotic life. We must settle what are the true, and what the apparent, differences between the two states, and then we must find a causal connection between the peculiar phenomena of hypnosis and the hypnosigenic method employed. An example will make this clearer. I will suppose that we want to find an explanation of a hypnotic negative hallucination of sight. We must first of all find an analogous phenomenon in a non-hypnotic state.

If we find a case in which, without hypnosis, an object is not perceived, though the eye must have seen it, we must then ask what is the difference between this phenomenon and the same phenomenon in hypnosis. We shall then find that in hypnosis objects are not perceived only when the experimenter forbids the perception; but that to forbid the perception of an object in waking life would be to ensure its being perceived. This point of difference must be kept in view for a proper explanation. It will be explained by the existence in the one case of a peculiar state of consciousness - dream-consciousness; and we must then ask how hypnosigenesis explains the formation of this dream-consciousness. It is a conspicuous flaw in many theories of hypnotism that they attempt to explain more than can be explained in the present state of our knowledge, and more than we are justified in demanding of them. An explanation of hypnosis is not called upon to explain the real nature of the process by which an idea is aroused; that is a problem for psychology in general to solve. Similarly, we have no right to demand that an explanation of hypnosis should explain the real nature of dream-consciousness as well. Certain facts must always be taken for granted.

Only superficial considerations could lead any one seeking to explain hypnosis to expect an explanation of the facts just mentioned. In studying psychological questions I always start from certain postulates, and never have anything to do with theories based on the theory of cognition. Similarly, any one who desires to explain hypnosis must accept certain postulates which he may, with a tranquil mind, leave to be explained later on by some other branch of psychology.

I think we can now explain many of the hypnotic phenomena, if "explanation" is taken in the above sense. About fifteen years ago I attempted to explain post-hypnotic suggestion in this way. In any case, such numerous analogies to the phenomena of hypnosis have already been found that it has been rescued from the domain of mysticism and occultism once and for all. We need no longer think the methods of hypnotism incomprehensible, as was the case formerly. This has, to an extent, been brought about by more careful methods of observation, by means of which it has been demonstrated that waking life, sleep, and other states present so many phenomena analogous to those of hypnosis, that the latter can hardly be said to present a symptom exclusively its own. Much progress has also been made by following the method recommended by Obersteiner; i.e., by studying the transitional states between normal life and hypnosis. In this way we have found many more connecting links with normal life than was originally expected.

Self-observation when practised by such intelligent investigators as Wilkinson, Bleuler, Forel, Obersteiner, North, August Heidenhain, Wundt, Dollken, Marcinowski, Straaten, Frau Bosse, Vogt, and Frau Vogt, has done much to further our comprehension of hypnotic phenomena.

Fr. Fuchs, it is true, has asserted that hitherto hypnotic experiments have only proved successful when the subjects have been priggish young men or young women, and not strenuous male adults. This shows how thoroughly Fuchs is acquainted with the literature of the subject. If he includes such men as Obersteiner, Bleuler, Forel, Wundt, etc., among the prigs, then an impartial observer will not have much difficulty in deciding who is the prig when he has to choose between Mr. Fuchs of Bonn and the gentlemen I have named.

We must never forget when endeavouring to explain hypnosis, that a uniform explanation is impossible, because the term hypnosis includes states that differ very much from one another. If we consider the remarks on the classification of hypnoses made on page 59, it at once becomes evident that Max Dessoir's two groups represent two totally different states, and Hirschlaff excludes the first group altogether from the category of hypnoses. At all events, when a subject retains consciousness and self-consciousness, there is an essential difference between his being unable to perform certain movements and his believing that he has been transported to another situation differing both as to time and place from the one in which he really is. But we could easily produce other types, apart from the two states just mentioned. For this reason I think it is better to discuss the chief symptoms of hypnotical phenomena simply, than to attempt to discover a uniform explanation for them all. I shall follow this plan and devote my attention to (1) the phenomena of suggestion as regards voluntary movement; (2) positive and negative delusions of the senses; (3) rapport; (4) the phenomena of memory; (5) post-hypnotic suggestion.