The traditional dating of the origin of psychoanalysis to 1900, when Freud published The Interpretation of Dreams, ignores the massive body of work he produced well before this date. Covering fields as diverse as neurology, physiology, philosophy, and pharmacology, this wealth of unjustly neglected material was to have a profound influence upon the development of psychoanalytic theory and technique. This fascinating study of the hidden roots of psychoanalysis features contributions from an international panel of authorities on Freud’s early writings, and highlights the unparalleled originality of his pre-analytic work. Seeking to restore the openness that originally existed between psychoanalysis and the other sciences, these papers consider Freud’s outstanding scientific achievements within neurology and his achievements as a psychologist. Freud’s early fascination with cocaine and his substantial monograph on the coca plant are reconsidered in the light of research that places the episode in its historical context. The influence of philosophical writings upon Freud’s thought is demonstrated careful consideration of the origins of Freudian concepts in the works of Aristotle, Brentano and John Stuart Mill.