In all departments of social evolution, progress is made by the twofold process of combination and differentiation.  We have dealt with detailed instances, and now it is profitable to treat the process in a larger way, with a view toward the possibilities of the future.  The Thirteen Colonies, somewhat similar in their earlier economic activities, united for mutual support much as wolves combine to form a pack.  Later, as circumstances directed, they differentiated into farming or manufacturing or commercial organs of the body politic, each to some degree freeing itself of the functions undertaken by others, and becoming thereby more dependent than before upon those that specialized in different ways.  As in the history of the insects in a growing wasp community and of savages evolving into barbarians, the original condition of relative independence passed into a state of interdependence and cooperation.  In like manner, if nature remains the same, as there is every reason to believe it will, nations now separate will unite to make more complex combinations that will be veritable empires of world-wide scope.  Countries on opposite sides of an ocean are now more closely connected by lines of communication and means of travel than were the Carolinas and New England a century ago.  Diplomatic activities give many signs of a growing appreciation of the value of reciprocal agreements for mutual advantage, and the Hague Conference is a concrete manifestation of a continuing process of social evolution that finds its beginnings and its interpretation far below human history in lower organic nature.

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.