Disadvantages of climate, deficiencies in food supply, competition from other species,—all these conditions society, in its organic strength, is easily able to overcome or to adjust. But in our inter-human relations we are not so successful. The serious dangers and troubles of human life arise from difficulties of adjustment with our social environment, and not with our physical environment. These difficulties, so far, have acted as a continual check to social progress. The more absolutely a nation has triumphed over physical conditions, the more successful it has become in its conquest of physical enemies and obstacles, the more it has given rein to the action of social forces which have ultimately destroyed the nation, and left the long ascent to be begun again by others. There is the moral of all human tales: ’Tis but the same rehearsal of the past,— First Freedom, and then Glory; when that fails, Wealth, Vice, Corruption,—barbarism at last. And History, with all her volumes vast, Hath but _one_ page.[1] Footnote 1: Childe Harold’s Pilgrimage, Canto IV., CVIII. The path of history is strewn with fossils and faint relics of extinct races,—races which died of what the sociologist would call internal diseases rather than natural causes. This, too, has been clear to the observer in all ages. It has been easily seen that there was something in our own behavior which did us more harm than any external difficulty; but what we have not seen is the natural cause of our unnatural conduct, and how most easily to alter it.