But perhaps the most important result of this whole discussion is the lesson of social service that it teaches. We are members of a vast community whose complex total life seems far removed from anything going on in an ant-colony, and our daily tasks vary greatly in specific character and degree when compared with those of lower communal organisms. It seems scarcely credible that any principles of social relationship, however general, can hold true for us and for them. But when the rock-bottom foundations are reached, they are simple and instructive indeed. Being here, we cannot escape our personal obligations as living things or our equally clear duties as members of our community. These facts being as they are, what must we do? Self-interest is rightly to be served, otherwise we would be incapable of discharging our secondary tasks, namely, those of service to others in ways that are determined by hereditary endowment and conditional circumstances. The difficulty is to find the right compromise between the two sets of obligations; but the right balance must be found, or else the health of the community is impaired. Should any class demand more than its just dues, others must suffer through the diversion of what they require, and the well-being of the selfish class is jeopardized to some degree, so closely interwoven are the interests of all. Freedom of opportunity within the limits of ability and efficiency is the right of every one, but freedom of conduct must never result in trespass upon the equal rights of others to make the most of their abilities and opportunities. To summarize, then, social evolution is a continuous process accomplished through differentiation and division of labor among the components of biological associations. Although the total form remains the same everywhere, progress has been made in content through the further subordination of selfish to altruistic conduct; only by this means does an individual gain liberty to pursue the social task for which he is best fitted by nature. VIII EVOLUTION AND THE HIGHER HUMAN LIFE