The principal stages in the history of hypnosis are reviewed, from the forerunners of Mesmer to the founder of "animal magnetism" himself, to Braid, and the entire hypnological movement of the nineteenth century. The work of Freud and the then and later relationships between hypnosis and psychoanalysis are discussed. A personal interpretation is offered for the phenomenon of the ups and downs of the popularity of hypnosis and reasons given for why its application should never decline again. After a brief review of modern theories of hypnosis and hypnotic techniques, the importance of the subject, over and above its uses in medical treatment, is emphasized, for hypnosis can be used as an invaluable tool for investigating the extraordinary reconstructional and creative possibilities inherent in the outer reaches of the human psyche.