Sigmund Freud created powerful theories in science and medicine that are still studied today. Freud was a neurologist who proposed many distinctive theories in psychiatry, all based on the method of psychoanalysis. Some of his key concepts include ego/superego/id, free association, trauma/fantasy, dream interpretation, jokes, and the unconscious. “Freud remained a determinist throughout his life, believing that all vital phenomena, including psychological phenomena such as thoughts, feelings, and fantasies, are rigidly determined by the principle of cause and effect” (Storr, 1989, p. 2). Through the discussion of these central concepts, Freud's theory of psychoanalysis becomes clear about how he interpreted human character. Freud believed that human nature was fundamentally deterministic and largely dependent on the unconscious mind. Irrational forces and unconscious motivations push the human mind towards unique conduct and performance. Freud believed that the choices we make are determined by biological and instinctive drives. The goals of the instincts are survival and aggression. In the field of psychiatry, Freud based his type of psychoanalytic therapy on the treatment of mental illnesses. The basis of Freud's work on the treatment of mental patients was a disease called hysteria. A popular case on which Freud began most of his work was the Anna O. case. She suffered from many symptoms due to repressed ideas that outwardly had no physical cause. Repression is a way of excluding unconscious unpleasant wishes, desires, or memories from the conscious mind by holding them in the unconscious mind. “According to Freud, repressed ideas often retained their power and were subsequently expressed without the patient's awareness. Via ps... half of the document... even if disproven or modified by today's psychologists, however its impact will always remain strong. His reflections on human behavior were profound and original, which makes his techniques for treating psychological illnesses innovative. His use of self-awareness for unconscious thoughts was a clever approach for its time. “The treatment principles enunciated by Freud were quite different from those followed by conventional physicians in the practice of medicine, and must have seemed revolutionary in the period before the First World War when they were formulated” (Storr, 1989, p. 95). The way modern psychotherapy and forms of psychoanalysis are conducted today is based on Freud's procedure (Storr, 1989, p. 95). Works Cited "Psychoanalysis". Compton of Britannica, v 6.0. January 27, 2009.Storr, A. (ed.). (1989). Freud. Oxford: Oxford University Press.