About the book: 2008 / Preface This book represents processed and supplemented my reports, read: 1) in 1932 at the Russian Scientific Institute in Belgrade; 2) in 1934 at the Russian Faculty of History and Philology in Paris and 3) in 1935 at the International Sociological Congress in Brussels. I express my deep gratitude to the Harvard Committee for Research in the Social Sciences {1} and Professor Pitirim Aleksandrovich Sorokin for assistance provided to me in carrying out this work. Paris, 1938.