In recent writings on Marx one finds an increasing interest in his humanism. This phenomenon began in the third decade of our century as a reaction against the mechanistic and stereotyped image of Marx 1 characteristic of the Second International and of Stalinism. Lukacs, in History and Class Consciousness (1923), was one of the first to discover this new Marx, and he did so even before the most important 2 of the humanistic writings of the young Marx had been discovered. With the publication ofthese writings in 1932 - namely, the Economic 3 and Philosophic Manuscripts of 1844 - this new outlook was given enormous impetus. In these Manuscripts, Marx makes the human being the creator and the goal of alI reality. The objectification of the human essence through labor transforms both society and nature. Labor transforms its wor1d into a place which mirrors, unfolds, and confirms the human being. This humanism is a complex and many-faceted issue. In this book we will be concerned only with a certain part of it, i.e., the epistemology, method, and doctrine of nature which it involves. Other aspects of it - Marx' concept of alienation and his theory of labor and the state -have 4 been dealt with elsewhere.