Psychoanalysis is a science that attempts to explain normal and pathological states in the human mind, as well as a clinical practice of treatment for the latter. It began with Freud's rejection of hypnosis and shock therapy as cures for hysteria and his development with Josef Breuer of the “talking cure,” a technique of analyzing patients' free associations that was to become a central feature of the psychoanalytic session. In Freud's account, psychoanalysis did not truly come into its own until he began to analyze the network of associations that arise in dreams; this was the breakthrough of his first major work, The Interpretation of Dreams. Describing dreams as the “royal road to . . . the unconscious,” Freud insisted that their images arise from the interaction between whole systems of repressed thoughts, as a result of which no single meaning can be affixed to any image.

Although this approach may seem reminiscent of the structuralist linguistics emerging around the time Freud was writing, nothing like it had existed before in the realm of dream interpretation.