Now four hundred years of unbroken triumph naturally bred in the white race an instinctive belief that its expansion would continue indefinitely, leading automatically to ever higher and more splendid destinies. Before the Russo-Japanese War of 1904 the thought that white expansion could be stayed, much less reversed, never entered the head of one white man in a thousand. Why should it, since centuries of experience had taught the exact contrary? The settlement of America, Australasia, and Siberia, where the few colored aborigines vanished like smoke before the white advance; the conquest of brown Asia and the partition of Africa, where colored millions bowed with only sporadic resistance to mere handfuls of whites; both sets of phenomena combined to persuade the white man that he was invincible, and that the colored types would everywhere give way before him and his civilization. The continued existence of dense colored populations in the tropics was ascribed to climate; and even in the tropics it was assumed that whites would universally form a governing caste, directing by virtue of higher intelligence and more resolute will, and exploiting natural resources to the incalculable profit of the whole white race. Indeed, some persons believed that the tropics would become available for white settlement as soon as science had mastered tropical diseases and had prescribed an adequate hygiene. This uncritical optimism, suggested by experience, was fortified by ill-assimilated knowledge. During the closing decades of the past century, not only were biology and economics less advanced than to-day, but they were also infinitely less widely understood, exact knowledge being confined to academic circles. The general public had only a vulgarized smattering, mostly crystallizing about catchwords into which men read their prepossessions and their prejudices. For instance: biologists had recently formulated the law of the "Survival of the Fittest." This sounded very well. Accordingly, the public, in conformity with the prevailing optimism, promptly interpreted "fittest" as synonymous with "best," in utter disregard of the grim truth that by "fittest" nature denotes only the type best adapted to existing conditions of environment, and that if the environment favors a low type, this low type (unless humanly prevented) will win, regardless of all other considerations. So again with economics. A generation ago relatively few persons realized that low-standard men would drive out high-standard men as inevitably as bad money drives out good, no matter what the results to society and the future of mankind. These are but two instances of that shallow, cock-sure nineteenth-century optimism, based upon ignorance and destined to be so swiftly and tragically disillusioned.