While the Darwinian theory explains thus the general descent of the animals, their transmutation and formation out of primitive beings, it explains, at the same time, the wonderful conformity throughout nature. Formerly this wonderful conformity could only be explained through the wise superintending care of God. Now, however, this natural descent is clearly understood. For this conformity is nothing else than the adaptation to the means of life. Every animal and every plant is exactly adapted to existing circumstances, for all those whose build is less conformable are less adapted and are exterminated in the struggle for existence. The green-frog, having descended from the brown-frog, must preserve its protecting color, for all those that deviate from this color are sooner found by the enemies and destroyed or find greater difficulty in obtaining their food and must perish. It was thus that Darwin showed us, for the first time, that new species continually formed out of old ones. The theory of descent, which until then was merely a presumptive inference of many phenomena that could not be explained well in any other way, gained the certainty of an absolute inference of definite forces that could be proved. In this lies the main reason that this theory had so quickly dominated the scientific discussions and public attention. II. MARXISM. If we turn to Marxism we immediately see a great conformity with Darwinism. As with Darwin, the scientific importance of Marx’s work consists in this, that he discovered the propelling force, the cause of social development. He did not have to prove that such a development was taking place; every one knew that from the most primitive times new social forms ever supplanted older, but the causes and aims of this development were unknown. In his theory Marx started with the information at hand in his time. The great political revolution that gave Europe the aspect it had, the French Revolution, was known to everyone to have been a struggle for supremacy, waged by the bourgeois against nobility and royalty. After this struggle new class struggles originated. The struggle carried on in England by the manufacturing capitalists against the landowners dominated politics; at the same time the working class revolted against the bourgeoisie. What were all these classes? Wherein did they differ from each other? Marx proved that these class distinctions were owing to the various functions each one played in the productive process. It is in the productive process that classes have their origin, and it is this process which determines to what class one belongs. Production is nothing else than the social labor process by which men obtain their means of subsistence from nature. It is the production of the material necessities of life that forms the main structure of society and that determines the political relations and social struggles.