Georg Simmel is one of the more paradoxical figures in twentieth-century thought. Among the founders of sociology as a discipline, and the influential teacher of many of the most important German social theorists of the modern era, Simmel left behind him no students devoted to his project and no school of research. As Jürgen Habermas writes, in his afterword to the 1983 edition of Simmel's book Philosophische Kultur (Philosophical Culture, 1911), Simmel "changed the mode of observation, the themes and style of writing of a whole generation of intellectuals." Yet, there remains no consistent academic method that can be traced directly to his teachings. Trained as a philosopher, Simmel is best known for his contributions to the nascent discipline of sociology. He wrote on a remarkably wide range of questions, however--from religion to fashion, ethics to history, flirtation to social conflict, the psychology of urban experience to the...