Tarde wrote a great deal. His flexibility of spirit and style add charm to his work on technical subjects. In criminology his principal works are: "The Philosophy of Punishment", "The Professional Criminal", "Comparative Criminality" (1898);--then come the political works, such as "The Transformation of Power" (1899). His "Transformation of Law" dates from 1894. His study in social psychology entitled "Opinion and the Masses" appeared in 1901. His most celebrated work is perhaps "The Laws of Imitation" (1900) which was preceded by his "Social Logic" (1898) and his "Universal Opposition" (1897). According to Tarde the social phenomena proceed from individual inventions which in their turn are the offspring of imitation: the latter is for Tarde a capital factor in social life. Original ideas or inventions germinate ceaselessly in the social _milieu_, but only some, either by their superior adaptability or through the peculiar authority of their inventor, are accepted by the public as a whole. Sociology is thus reduced to a Psychology of the _processus_ of invention and imitations. This explains why the great effort of Tarde has been to discover the "Laws of Invention". Thereby he has given in sociology a preponderating place to the individual, and the accidental, and has thus separated himself from the most general tendencies of thought in our times which are those of Comte. The style of Tarde is abstract but supple. This fragment of future History forms a kind of exception to his general work which is very abstract. Tarde reveals himself in it one of the masters of literary French. The style is picturesque, intense, broad, even periodic, novel in respect to the thought, and entirely classical in its purity. Joseph Manchon.