Until the beginning of the twentieth century, most people considered dreams unworthy of serious consideration. Sigmund Freud, however, had noticed that they formed an active part in the analysis of his patients, and he gradually came to believe that they represent struggles by the unconscious to resolve conflicts. In this classic of psychology, Freud explains the dual nature of dreams ― their apparent content and their true, if hidden, meaning ― as well as the concept of wish fulfillment and a universal language for interpreting dreams.

This groundbreaking work also contains Freud's introduction of the notion that sexuality plays an important role in childhood, a theory that deeply shocked his contemporaries. Psychological journals rejected the book, and scientific publications ignored it, but the author recognized it as containing his greatest insights. The Interpretation of Dreams eventually helped set the stage for psychoanalytic theory, and it remains Freud's most original work.