We have the obverse of this post-hypnotic suggestion in the phenomenon of =double consciousness=. A subject is hypnotised and becomes somnambulistic; when he is waked, he has no memory whatsoever of the events that occurred during the hypnotic state. Later, he is hypnotised again; and now it turns out that he remembers what took place during the previous hypnosis. So he seems to have a double consciousness; the normal waking consciousness, which is sensibly continuous in his waking states, and a secondary hypnotic consciousness, which is continuous from one state of somnambulism to another. There is, again, nothing mysterious in the facts; we have their parallel in the normal shifts of personality; we have seen that a man is a different self in the office, on the golf-links, with his children in the nursery; and we have now only to add that the known laws of memory are adequate to these phenomena of double consciousness. For we do not pass in thought from one situation to another unless the situations are connected by some idea which is common to them both; the hard-worked professional man, when he is on the links, _forgets_ the office; that is the reason for his play; and he forgets the office because there is no community of ideas between his work and his recreation. In hypnosis, too, we break sharply with the waking life; if the two are to be connected, a bridge must be built _ad hoc_ by the operator; but when we relapse into hypnosis we pick up again the thread of our hypnotic memory, as naturally as the professional man picks up his work when he seats himself at his desk after a half-holiday.