– Sigmund Freud (1856-1939). Dr. Freud has been credited as being the founder of talk therapy, or psychotherapy. He developed therapeutic techniques such as the use of free association (in which patients report their thoughts without reservation and in whichever order they spontaneously occur) and discovered transference (the process in which patients displace on to their analysts feelings derived from their childhood attachments), establishing its central role in the analytic process. His analysis of his own and his patients’ dreams as wish-fulfillments provided him with models for the clinical analysis of symptom formation and the mechanisms of repression as well as for elaboration of his theory of the unconscious as an agency disruptive of conscious states of mind. Freud postulated the existence of libido, an energy with which mental process and structures are invested and which generates erotic attachments, and a death drive, the source of repetition, hate, aggression and neurotic guilt.In his later work Freud drew on psychoanalytic theory to develop a wide-ranging interpretation and critique of religion and culture.