Having learned the difference between men and animals, let us now again consider how they are affected by the struggle for existence. That this struggle is the cause of perfection and the weeding out of the imperfect, can not be denied. In this struggle the animals become ever more perfect. Here, however, it is necessary to be more precise in expression and in observation of what perfection consists. In being so, we can no longer say that animals as a whole struggle and become perfected. Animals struggle and compete by means of their particular organs. Lions do not carry on the struggle by means of their tails; hares do not rely on their eyes; nor do the falcons succeed by means of their beaks. Lions carry on the struggle by means of their saltatory (leaping) muscles and their teeth; hares rely upon their paws and ears, and falcons succeed on account of their eyes and wings. If now we ask what is it that struggles and what competes? the answer is, the organs struggle. The muscles and teeth of the lion, the paws and ears of the hare, and the eyes and wings of the falcon carry on the struggle. It is in this struggle that the organs become perfected. The animal as a whole depends upon these organs and shares their fate. Let us now ask the same question about the human world. Men do not struggle by means of their natural organs, but by means of artificial organs, by means of tools (and in weapons we must understand tools). Here, too, the principle of perfection and the weeding out of the imperfect, through struggle, holds true. The tools struggle, and this leads to the ever greater perfection of tools. Those groups of tribes that use better tools and weapons can best secure their maintenance, and when it comes to a direct struggle with another race, the race that is better equipped with artificial tools will win. Those races whose technical aids are better developed, can drive out or subdue those whose artificial aids are not developed. The European race dominates because its external aids are better. Here we see that the principle of the struggle for existence, formulated by Darwin and emphasized by Spencer, has a different effect on men than on animals. The principle that struggle leads to the perfection of the weapons used in the strife, leads to different results between men and animals. In the animal, it leads to a continuous development of natural organs; that is the foundation of the theory of descent, the essence of Darwinism. In men, it leads to a continuous development of tools, of the means of production. This, however, is the foundation of Marxism.