Psychoanalysis is a set of theories and techniques of research to discover unconscious processes and their influence on conscious thought, emotion and behavior. Based on dream interpretation, psychoanalysis is also a talk therapy method for treating mental disorders. Established in the early 1890s by Sigmund Freud, it takes into account Darwin's theory of evolution, neurology findings, ethnology reports, and, in some respects, the clinical research of his mentor Josef Breuer. Freud developed and refined the theory and practice of psychoanalysis until his death in 1939. In an encyclopedic article, he identified its four cornerstones: "the assumption that there are unconscious mental processes, the recognition of the theory of repression and resistance, the appreciation of the importance of sexuality and of the Oedipus complex."
Freud's earlier colleagues Alfred Adler and Carl Jung soon developed their own methods (individual and analytical psychology); he criticized these concepts, stating that they were not forms of psychoanalysis. After the author's death, neo-Freudian thinkers like Erich Fromm, Karen Horney and Harry Stack Sullivan created some subfields. Jacques Lacan, whose work is often referred to as Return to Freud, described his metapsychology as a technical elaboration of the three-instance model of the psyche and examined the language-like structure of the unconscious.
