The outstanding French psychologist Pierre Janet is the author of the term "interiorization," so important for the concept of L. S. Vygotsky, and the cathartic method of treating neurosis, usually associated with the name 3. Freida, - surprisingly little known to the Russian reader. In his early work "Mental automatism," Janet analyzes in detail various cases of natural and hypnotic somnambulism, one of the first to describe the phenomena of personality multiplicity ("the simultaneous existence of several psyches"), shows the possibilities of treatment with the help of hypnosis of various functional disorders. For psychologists, sociologists, doctors.