Melanie Klein (1882–1960) pioneered psychoanalytic practice with children and made major contributions to our understanding of both psychosis and autism. Along the way, she introduced a new approach to the theory of the unconscious without abandoning the principles set forth by Freud. In her first biography of a fellow psychoanalyst, Julia Kristeva considers Klein’s life and intellectual development, weaving a narrative that illuminates her own life and work. Kristeva tells the remarkable story of Klein’s life: an unhappy wife and mother who underwent analysis and—without a medical or other advanced degree—became an analyst herself at the age of 40. In Kristeva’s account, Klein was the first person to see the mother as the source of not only creativity but also thought itself and the first to consider the place of matricide in psychic development—making her a crucial figure in the evolution of the provocative ideas about motherhood and the psyche for which Kristeva is renowned.