FRO M the beginning of his psychological investigations the boundless curiosity of Freud's genius had been excited by the apparent inexplicability of neurotic symptoms-inexplicable in terms of common sense and the conscious wish of the otherwise normal patient, and inexplicable in terms of the medical and psychiatric knowledge of that era. This curiosity had led Freud to his hypnotic experimentE with Breuer and to the traumatic theory of hysteria, followed by the exploration of repressed sexual and punishment phantasies, the understanding of conflict and repression, and the inductive creation of instinct theory to explain the dynamic effect of repressed ideas in the production of conscious symptoms.