Man is a part of nature and a product of nature; in many fundamental respects his ways are still nature's ways and his laws still nature's laws. But there are other and even more significant ways in which man has separated himself from nature and made himself something quite different. In order to reveal this clearly, we draw a distinction between nature and man. This is a proper thing to do, provided we bear in mind that our classification is not permanent or final. We distinguish frogs from tadpoles, in spite of the fact that at one stage the creature is half tadpole and half frog. We distinguish the animal from the vegetable kingdom, despite the fact that in their lower forms they cannot be distinguished. What, precisely, is the difference between nature and man? The difference lies in the fact that nature is apparently blind in her processes; she produces a million eggs in order to give life to one salmon, she produces countless millions of salmon to be devoured by other fish apparently no better than salmon. Poets may take up the doctrine of evolution and dress it out in theological garments, talking about the "one far off divine event towards which the whole creation moves," but for all we can see, nature, apart from man, is just as well satisfied to move in circles, and to come back exactly where she started. Nature made a whole world of complicated creatures in the steamy, luke-warm swamps of the Mesozoic era, and then, as if deciding that the pattern of a large body and a small brain was not a success, she froze them all to death with a glacial epoch, and we have nothing but the bones to tell us about them. No one understands anything about evolution until he has realized that the phrase "the survival of the fittest" does not mean the survival of the best from any human point of view. It merely means the survival of those capable of surviving in some particular environment. We consider our present civilization as "fit"; but if astronomical changes should cause another ice age, we should discover that our "fitness" depended upon our ability to live on lichens, or on something we could grow by artificial light in the bowels of the earth.