Sigmund Freud (1856–1939) was an Austrian neurologist and the founder of psychoanalysis, a clinical method for treating psychopathology through dialogue between a patient and a psychoanalyst. He developed techniques such as the use of free association and identified the phenomenon of transference. His analysis of dreams as wish-fulfillments provided him with models for the underlying mechanisms of repression, and on this basis he elaborated his theory of the unconscious and went on to develop a model of psychic structure comprising id, ego, and superego. He also postulated the existence of libido, a sexualized energy that generates erotic attachments, and a death drive, the source of compulsive repetition, hate, aggression, and neurotic guilt.
Franz Gabriel Alexander has been described on more than one occasion as the father of psychosomatic medicine. For almost 25 years, he was director of the Chicago Institute of Psychoanalysis, where he trained many of the leading students of emotional disturbances and psychosomatic diseases.