"Mental Illness and Psychology" (1962) is a revised and expanded version of Foucault's early essay (1954), supplemented by the main theses of his doctoral dissertation, "The History of Madness in the Classical Age," which he defended the previous year. This book allows us to trace the origin and evolution of Foucault's distinctive ideas through a consistent critical examination of concepts of madness inherent in physiology, psychoanalysis, existential psychology, and antipsychiatry. Here he attempts to refute one of the classic assertions in the history of psychology, according to which the emergence of psychiatric medicine would liberate the "mad." The philosopher, on the contrary, demonstrates that the true alienation of madness must be dated to the moment when it began to be designated and treated as an illness. The essay reflects, on the one hand, Foucault's professional experience: working as a prison psychologist and teacher of the history of psychology, and, on the other, his personal experiences of his own "marginality" and "abnormality."