Sigmund Freud (1856-1939) developed the theory and practice of psychoanalysis, one of the twentieth century's most influential schools of psychology. He also made profound insights into the psychology and understanding of human beings. In this brilliant and long-awaited introduction, Jonathan Lear--one of the most respected writers on Freud--shows how Freud also made fundamental contributions to philosophy and why he ranks alongside Plato, Aristotle, Marx and Darwin as a great theorist of human nature. Freud is one of the most important introductions and contributions to understanding this great thinker to have been published for many years, and will be essential reading for anyone in the humanities, social sciences and beyond with an interest in Freud or philosophy.