Charcot's well-known phases lethargy, catalepsy, and somnambulism, depend on prepared hypnosis of hysterical persons. Bernheim attempted to introduce a classification in several degrees. However, there is no possibility of a precise limitation. I consider that it suffices to accept three degrees of suggestibility, which, however, can have transitions: (1) Somnolence. The lightly influenced person can resist the suggestion by the exercise of his energy, and can open his eyes. (2) Light sleep, otherwise called hypo-taxis or "charme." Here the influenced person can no longer open his eyes, and is obliged to obey a part of the suggestions or all of them, with the exception of amnesia. He does not become amnesic (3) Deep sleep or somnambulism. This is characterized by amnesia after awakening. The term "somnambulism" is, in my opinion, not a happily chosen one, since it gives rise to confusion with spontaneous somnambulism. The latter is a mild but nevertheless true pathological condition, which appears to be frequently connected with hysteria, and is not simple hypnotism. Posthypnotic phenomena may occur, not infrequently in my experience, even after light sleep. Suggestibility may, under certain circumstances, be very slight, or even almost absent, in very deep sleep (very rare cases). However, one can produce sleep with open eyes, the result of suggestion in waking condition, as well as amnesia, and, conversely, memory by means of suggestion, so that the three degrees are very ill-defined. The sleep, the amnesia, and the capability of resistance are herein only used as tests of the suggestibility. It depends chiefly on what one has suggested at first.

One can further transform somnolence into hypotaxis by means of suggestion with practice and training, and hypotaxis into somnambulism by means of suggestion of amnesia, although this does not always succeed.