From 1908 he was the lecturer on mediaeval history of the Warsaw Society for Scientific Courses (TKN). In 1919 he became a professor of the University of Warsaw and headed the Department of Polish History of the Middle Ages and of Auxiliary Sciences of History. During the 1920/1921 academic year he was also the rector of the University of Warsaw. In 1928-1930 he held a seat in Sejm on behalf of the Nonpartisan Bloc for Cooperation with the Government (BBWR). His books include the following works: Kazimierz Wielki, zarys żywota i panowania (1899-1900), Witold, Wielki Książę Litewski (1900), O heraldyce czyli o znajomości herbownictwa (1902), Postęp ludzkości jako wyraz praw psychicznych rozwoju (1917), Polska w świetle psychiki własnej i obcej (1920), and Wśród zagadnień naszej doby (1934).