The author, S. M. Dubnow, occupies a dominating position in Russian-Jewish literature as an historian and an acute critic. His investigations into the history of the Polish-Russian Jews, especially his achievements in the history of Chassidism, have been of fundamental importance.The author attempts, for the first time, a psychologic characterization of Jewish history. He endeavors to demonstrate the inner connection between events, and develop the ideas that underlie them, or, to use his own expression, lay bare the soul of Jewish history.