Schmidt's close reading of Marx's own writings and his relation of them to the positions of Kant, Hegel, Engels, Lenin, the early Lukacs and Sartre, enables him to establish the significance of the mature Marx's sense of the interpenetration of nature and society. He shows how Marxism cuts right across the traditional tendency to counterpose an abstract concept of man with an abstract concept of nature. Schmidt stresses the importance in Marxism of the development of industry and science as the mediation between historical man and external nature, leading either to their reconciliation (if positive) or to their mutual annihilation (if negative). He then both explores this mediation in history and shows how an awareness of its positive and negative possibilities is reflected in such writers as Bertolt Brecht, Walter Benjamin and Ernst Bloch.