This could be accomplished in no other way than by simultaneously determining, in its capacity as a theory of understanding, the relation of the world around us to the image which our mind forms of it. In this respect Dietzgen completed the work begun by Hume and Kant. As a theory of understanding, his conceptions are not only the philosophical basis of historical materialism, but also of all other sciences as well. The thorough critique directed by Dietzgen against the works of prominent natural scientists, shows that he was well aware of the importance of his own work. But, as might be expected, the voice of a socialist artisan did not penetrate to the lecture hall of the academies. It was not until much later that similar views appeared among the natural scientists. And now at last the most prominent theorists of natural science have adopted the view that explaining signifies nothing else but simply and completely describing the processes of nature. By this theory of understanding Dietzgen has made it plainly perceptible why the dialectic method is an indispensable auxiliary in the quest for an explanation of the nature of understanding. The mind is the faculty of generalization. It forms out of concrete realities, which are a continuous and unbounded stream in perpetual motion, abstract conceptions that are essentially rigid, bounded, stable, and unchangeable. This gives rise to the contradiction that our conceptions must always adapt themselves to new realities without ever fully succeeding; the contradiction that they represent the living by what is dead, the infinite by what is finite, and that they are themselves finite though partaking of the nature of the infinite. This contradiction is understood and reconciled by the insight into the nature of the faculty of understanding, which is simultaneously a faculty of combination and of distinction, which forms a limited part of the universe and yet encompasses everything, and it is furthermore solved by the resulting penetration of the nature of the world. The world is a unity of the infinitely numerous multitude of phenomena and comprises within itself all contradictions, makes them relative and equalizes them. Within its circle there are no absolute opposites. The mind merely constructs them, because it has not only the faculty of generalization but also of distinguishing. The practical solution of all contradictions is the revolutionary practice of infinitely progressing science which moulds old conceptions into new ones, rejects some, substitutes others in their place, improves, connects and dissects, still striving for an always greater unity and an always wider differentiation.