In any consideration of the nature of suggestion we cannot omit reference to the extraordinary and startling phenomena which may sometimes be observed in hypnotized subjects. But it would be a mistake to look upon hypnosis as something uncanny, mysterious, and occult. Although we have even yet no thoroughly satisfactory theory of hypnosis, we understand it in general terms, and can bring it into line with other facts and phenomena of psychology known in everyday life. hypnotic subject, and the phenomena of hypnosis, can be explained firstly in terms of mental dissociation, of the tendency for certain forms of psychical activity to occur independently of the rest of the mind, independently of other considerations; and, secondly, in terms of suggestion, of increased suggestibility. And these two, the phenomenon of dissociation and the phenomenon of suggestibility, are not unrelated to one another. They are related, but not to the extent of being identical with one another. It was the Nancy School of Hypnotism, led by Bernheim, who considered that hypnosis could be explained in terms of suggestibility. Charcot had previously explained hypnosis as an artificial hysteria-as a dissociation of the highest levels of the nervous system, a dissociation of mental and physiological activity at the higher conscious level. But the theory I am trying to sketch is the theory that combines both these statements. In my own view, based on the study of many hundreds of cases, hypnosis is explained both by dissociation and by increased suggestibility. We certainly do find increase of suggestibility occurring, partly explained in terms of dissociation, but not entirely so. On the other hand, the dissociation in its more pronounced forms may show itself independently of suggestibility. Which is the cause and which the effect of these two ? Dissociation as a cause may bring with it increase of suggestibility. We can understand why that should be so. Does increased suggestibility on its side bring dissociation? It may tend to do so. A person who is in an increasingly suggestible state responds to just the one stimulus before him-it may be a stimulus from the outer world, or an idea aroused in his mind by the experimenter. He responds with his whole mind and strength to the 1 Being part of a paper on The Self: Psycho-Analysis and PsychoTherapy, read before the Church Congress, Newport, Mon., on October 8,