This document provides an overview of psychoanalysis and its development. It discusses how psychoanalysis emerged from 18th century intellectual movements and was further influenced by 19th century thinkers. The document then focuses on Sigmund Freud and his development of psychoanalytic theory, including his concepts of the id, ego, and superego; psychosexual stages; and defense mechanisms. It also notes some common criticisms of psychoanalysis and Freud's theories.