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. The 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.