Since the individual human bodies and minds which seek after the things to which we mortals attach value--moral worth, esthetic and other pleasure, achievement and the like--do have to be replaced every few years, the germplasms from which new individuals must come have always been and always will be of fundamental importance. It is always the _product_ of the germplasm which concerns us, and we are interested in the germ-cells themselves only in relation to their capacity to produce individuals of value to society. So let us not go erring about in the philosophical ether, imagining that because the _amoeba_ may not be specialized for anything over and above nutrition and reproduction that these are necessarily the "main business" or "chief ends" of human societies. Better say that although we have become developed and specialized for a million other activities we are still bound by those fundamental necessities. As to "Nature's purposes" about which the older sex literature has had so much to say, the idea is essentially religious rather than scientific. If such "purposes" indeed exist in the universe, man evidently does not feel particularly bound by them. We do not hesitate to put a cornfield where "Nature" had a forest, or to replace a barren hillside by the sea with a city. Necessities and possibilities, not "purposes" in nature, claim our attention--reproduction being one of those embarrassing necessities, viewed through the eyes of man, the one evaluating animal in the world. Thus in reasoning from biology to social problems, it is fundamental to remember that man as an animal is tremendously differentiated in functions, and that most of the activities we look upon as distinctively human depend upon the body rather than the germ-cells. It follows that biology is the foundation rather than the house, if we may use so crude a figure. The solidity of the foundation is very important, but it does not dictate the details as to how the superstructure shall be arranged. Civilization would not be civilization if we had to spend most of our time thinking about the biological basis. If we wish to think of "Nature's" proscriptions or plans as controlling animal life, the anthropomorphism is substantially harmless. But man keeps out of the way of most of such proscriptions, has plans of his own, and has acquired considerable skill in varying his projects without running foul of such biological prohibitions.