Leszek Kolakowski (1927-2009) was professor of philosophy at the University of Warsaw until the Polish political crisis of March 1968 when he was formally expelled. He then moved to universities in North America and the United Kingdom. From 1981 to 1994 he was a professor in the Committee on Social Thought and the department of philosophy at the University of Chicago. He is best known for his critical analyses of Marxist thought, especially his three-volume history, Main Currents of Marxism (1976). In his later work, he increasingly focused on philosophical and religious questions. He was the author of numerous books.