The Nihilism of Socialism springs from the Materialist Conception of History, and this is precisely the portion of the socialist doctrine that is usually ignored or half-understood by the enthusiastic young intellectuals who are in growing numbers joining the Socialist movement on both sides of the Atlantic. While the Communist Manifesto, written by Karl Marx and Friedrich Engels in 1847, is throughout founded on this conception, the first clearly formulated statement of the conception itself is to be found in the Preface to the "Contribution to the Critique of Political Economy," published by Karl Marx in 1859, the same year in which Darwin and Wallace made public their independent and almost simultaneous discoveries of the theory of Natural Selection. This first statement runs thus: "In the social production which men carry on they enter into definite relations that are indispensable and independent of their will; these relations of production correspond to a definite stage of development of their material powers of production. The sum total of these relations of production constitutes the economic structure of society--the real foundation, on which rise legal and political superstructures and to which correspond definite forms of social consciousness. The mode of production in material life determines the general character of the social, political, and spiritual processes of life. It is not the consciousness of men that determines their existence, but, on the contrary, their social existence determines their consciousness. At a certain stage of their development, the material forces of production in society come in conflict with the existing relations of production, or--what is but a legal expression for the same thing--with the property relations within which they had been at work before. From forms of development of the forces of production these relations turn into their fetters. Then comes the period of social revolution. With the change of the economic foundation the entire immense superstructure is more or less rapidly transformed."[9] This statement contains a whole Revolution in embryo. Viewed from the standpoint of the established order, it is the very Quintessence of Nihilism. In a word, it teaches the material origin of Ideas. In the last analysis, every idea can be traced back to the economic and telluric environments. In the words of Joseph Dietzgen, "philosophy revealed to them (Marx and Engels) the basic principle that, in the last resort, the world is not governed by Ideas, but, on the contrary, the Ideas by the material world." This doctrine involves a new epistemology, the distinguishing mark of which is its denial of the immaculate conception of thought. The human mind, according to Marx and Dietzgen, can only bring forth thought after it has been impregnated by the objects of sense perception.[10]