Georg Simmel was a major German sociologist, philosopher, and critic.Simmel was one of the first generation of German sociologists: his neo-Kantian approach laid the foundations for sociological antipositivism, asking 'What is society?' in a direct allusion to Kant's question 'What is nature?', presenting pioneering analyses of social individuality and fragmentation. For Simmel, culture referred to "the cultivation of individuals through the agency of external forms which have been objectified in the course of history". Simmel discussed social and cultural phenomena in terms of "forms" and "contents" with a transient relationship; form becoming content, and vice versa, dependent on the context. In this sense he was a forerunner to structuralist styles of reasoning in the social sciences. With his work on the metropolis, Simmel was a precursor of urban sociology, symbolic interactionism and social network analysis. An acquaintance of Max Weber, Simmel wrote on the topic of personal character in a manner reminiscent of the sociological 'ideal type'. He broadly rejected academic standards, however, philosophically covering topics such as emotion and romantic love. Both Simmel and Weber's nonpositivist theory would inform the eclectic critical theory of the Frankfurt School.Simmel's most famous works today are The Problems of the Philosophy of History (1892), The Philosophy of Money (1907), The Metropolis and Mental Life (1903), Soziologie (1908, inc. The Stranger, The Social Boundary, The Sociology of the Senses, The Sociology of Space, and On The Spatial Projections of Social Forms), and Fundamental Questions of Sociology (1917). He also wrote extensively on the philosophy of Schopenhauer and Nietzsche, as well on art, most notably his book Rembrandt: An Essay in the Philosophy of Art (1916).