The article presents the results of a doctoral dissertation defended at the Universidad de Salamanca, based on Foucault's final decade of writings. If Foucault's goal in writing The History of Sexuality was to fashion a genealogy of ethics, my goal in analyzing this book, along with his other writings, is to demonstrate his last contribution to the history of medicine. He moves from a conception of power over others towards a conception of power over oneself, an exclusive terrain of ancient Greek morality. As a thinker who tries to understand today's problems by going to their roots, Foucault develops less a history than a philosophy of history. Considered an anti-humanist, he leaves us with a portrait of a wholly ethical-humanistic medicine.