The author traces 19th-century origins of sociology in post-Revolutionary Europe, and contrasts European and American approaches to sociological data. Using the concepts of mass behavior and mass society as case studies, he suggests the continuing influence of social and political philosophies in sociology to the present day. Originally published in 1961. The Princeton Legacy Library uses the latest print-on-demand technology to again make available previously out-of-print books from the distinguished backlist of Princeton University Press. These editions preserve the original texts of these important books while presenting them in durable paperback and hardcover editions. The goal of the Princeton Legacy Library is to vastly increase access to the rich scholarly heritage found in the thousands of books published by Princeton University Press since its founding in 1905.