Possession can be readily evoked in nearly all hypnotic subjects. Not only one but several distinct personalities can be developed by the psychologist. Janet’s experiments developed in Madame B. three separate individuals: Léonie, known in the waking state as a “possessor”; Léontine under the light stage of hypnosis, and Léonore in a deeper condition.[40] Even a popular knowledge and comprehension of this peculiar disease of the subconscious is difficult to attain without a sound elementary grasp of the principles of psychology. The bulk of books on the subject are written for the medical or scientific mind, but Coriat’s book is a sound and easily grasped introductory manual.[41] The normal form of mental trouble is an obsession, the fear or “phobia” of some perfectly normal thing, a desire to touch objects. There are dozens of variations of these obsessions which spring to mind. The state of possession can only be said to exist when the mind is under the dominance of another individuality distinct from the normal personality. It is curious to note that cases of possession by good spirits are absolutely unknown. A medium may be “controlled” by spirits said to be good, but this does not amount to a possession. In every case where normal personality has been overthrown and another or other personalities take possession we find--evil. This is to certain extent explicable if we realize that every thought or wish that occurs to us, and which we _repress_ because it is bad or evil, is not destroyed or wiped out of existence, but stays as a suppressed desire or wish buried in the recesses of subconscious mind. When normal conscious control is overthrown, these subconsciously stored desires or wishes come bubbling up--a fact that seems to explain why the language used by nicely brought up girls recovering after the administration of an anæsthetic would put a coal-heaver to flight. In the dream state, too, these repressed desires escape all mixed up from their bondage, a fact which accounts for the peculiar medley of dreams and their frequent lack of moral balance and accentuation of sexual characteristics. The character of a “possessing” demon is in most cases determined by experiences that the victim has passed through. Shock, neurasthenia, illness, disappointment; all these may bring about the splitting of the personality so that the secondary or possessing personality can overthrow consciousness and take charge. The victim is often horrified to find his or her mind continually filled with terrible desires, intolerable passions, and thoughts utterly repugnant to the sedate conscious self. Sometimes the idea of possession is stimulated by messages received through mediums or by automatic writing--this is one of the many frequent cases where undigested, uneducated Spiritualism is often abominably harmful. Anything that helps the idea of possession to grow in the afflicted mind should be avoided.