Throughout history, Shari'ati reminds us in these lectures and writings, people in search of deliverance from constricting social and intellectual systems have all too often followed influential thinkers out of one form of captivity and directly into another. He warns that great case must be taken in this day of search and upheaval to examine the prevailing movements that promise solutions for humanity. Marxism, which holds special appeal for the world's oppressed peoples and those sensitive to their suffering because of its emphasis on justice, merits particularly close scrutiny. Shari'ati analyzes its roots in materialism, its relation to the Hegelian dialectic, its preoccupation with matters of production, the sources of its diametrical opposition to Islam, Marx's objection to religion, and other crucial aspects to Marxism. But his attention is not confined to Marxism alone. He discusses the established religions, bourgeois liberalism, and existentialism, beginning with their fundamental notions of man. He examines the characteristic refusal of the major freedom-seeking movements of the nineteenth and twentieth centuries to accept any spiritual dimension in man. Throughout his inquiry, Shari'ati offers comparisons with the ideology of Islam, drawing upon the principles and precepts contained in the Qur'an as well as cultural material from the history of Islamic society. Gradually and eloquently, he expounds his personal view of Islam as the philosophy of human liberation.