I may, then, confess in spite of my authorship, that I am not a professor of philosophy, but a mechanic by profession. If any one should feel justified in telling me: "Shoemaker, stick to your last!" I would reply to him with Karl Marx: "Your non plus ultra professional wisdom became enormously foolish from the moment when the watchmaker Watt invented the steam engine, the barber Arkwright the loom, the jeweler Fulton the steamship." Without classing myself among these great men, I can strive to emulate them. Besides, the nature of my object is especially pertinent to the class, a member of which I have the pleasure, if not the honor, of being. I treat in this work of the faculty of thought as the organ of the general. The oppressed fourth estate, the working class, is the true exponent of this organ, the ruling classes being prevented by their special class interests from recognizing the demands of general reason. Our first consideration is, of course, the relation of our object to human conditions. However, so long as conditions are not equalized for men in general, but vitiated by class interests, our view of things is influenced by these class limitations. A truly objective understanding requires a subjective theoretical freedom. Before Copernicus saw the Earth was moving and the Sun stationary, he had to place himself outside of his terrestrial standpoint. The faculty of thought, having all relations for its object, must abstract from all of them in order to grasp its own real nature. Since we can understand things only by means of thought, we must abstract from everything in order to understand thought in general. This task was too difficult, so long as man was bound to some limited class standpoint. Not until historical development has proceeded to the point of striving at dissolution of the last society based on a ruling and a serving class, can prejudices be overcome to the extent of enabling the faculty of understanding to grasp the nature of human brain activity in the abstract. It is only a historical movement aiming at the direct and general liberty of the masses, the new era of the fourth estate based on much misunderstood premises, which can dispense with the spirit cult sufficiently to be enabled to expose the real author of every spook, the "pure" mind. The man of the fourth estate represents at last the "pure" man. His interests are no longer mere class interests, but mass interests, interests of humanity. This indicates that we are now approaching the end of a development in which the interests of the mass were dependent on the interests of a ruling class and in which humanity made progress not so much in spite of as by means of continuous oppression by Jewish patriarchs, Asiatic conquerors, antique slaveholders, feudal barons, guildmasters, modern capitalists and even capitalist Caesars. The class conditions of the past were inevitable in the general development. Now