Psychoanalysis comprises a set of theories and techniques to discover unconscious processes and their influence on conscious thought, emotion and behavior. Psychoanalysis is 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 clinical research, including findings 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 four foundational beliefs: "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."