Gabriel Tarde (Sarlat, 1843- Paris, 1904) studied law in Toulouse and Paris, while they assiduously read the mystics, the Stoics or authors like Maine de Biran, Hegel and Cournot. Author autodidact, during his years as a judge in Sarlat instructor will contact social situations that will cause their own theoretical investigations. From 1880, he began to publish in the Revue philosophique. In 1893, he becomes co-director of the Archives de l'anthropologie criminelle, magazine in 1907 published "Sexual morality." Since 1894 he is actively involved in discussions of sociology, and is president of the Society of Sociology of Paris. In 1900, the College de France offers the chair of Modern Philosophy (which Henri Bergson be his successor) and is appointed to the philosophy section of the Academy of Moral and Political Sciences. His great books are: Comparative crime (1886), Laws of Imitation (1890), The penal philosophy (1890), Transformations of Law (1893), The social logic (1895), Social laws (1898) transformations of power (1899) and the view and the crowd (1901).