The family is the most striking case of solidarity. It is first formed of two units at opposite poles in point of sex, experience, taste, need, and aims; and when they form it, they usually have as much sense of sacredness as their character is capable of feeling. When children are added, more divergences of age, capacity, and need are injected. Yet out of these contradictory elements a social fellowship is built up, which, in the immense majority of cases, defies the shocks of life and the strain of changing moods and needs, forms the chief source of contentment for the majority of men and women, and, when conspicuously successful, wins the spontaneous tribute of reverence from all right-thinking persons. In using the equipment of the home, in standing by one another in time of sickness and trouble, and in spiritual sympathy, a true family practices solidarity of interests, and furnishes the chief education in cooperation. Political unity was at first an expansion of family unity. The passionate loyalty with which a nation defends its country and its freedom, is not simply a defence of real estate and livestock, but of its national brotherhood and solidarity. The devotion with which people suffer and die for their State is all the more remarkable because all States hitherto have been largely organizations for coercion and exploitation, and only in part real fraternal communities. Patriotism hitherto has been largely a prophetic outreaching toward a great fellowship nowhere realized. The peoples walk by faith. What evidence does college life furnish us of the fact that social unity is realized with some sense of sacredness? Why do the years in college stand out in the later memories of graduates with such a glamour? Why do students devote so much unpaid service to their teams and fraternities? Is it for the selfish advantages they hope to get, or because they feel they are realizing the best of life in being part of a solidaristic group? Do the dangers of college organizations prove or disprove the principle that fellowship is felt to be something sacred? Any historical event in which men stood by their group through suffering or to death is remembered with pride. Any case of desertion or betrayal is remembered with shame. No group forgives those who sell out its solidarity for private safety or profit. Insurance and cooperation are two great demonstrations of the power of solidarity. In insurance we bear one another’s burdens, “and so fulfil the law of Christ.” The cooperative associations, which have had such enormous success in Europe, succeed only where neighborhood or common idealistic conviction has previously established a consciousness of social unity. They have to overcome the most adverse conditions in achieving success. When they do, the effect on the economic prosperity of the people and on their moral stability and progressiveness is remarkable. II