the extent of the uniform surface is in large degree the measure of national strength and permanence. Irregular or rugged surfaces, as compared with the uniformity of plains, are naturally less heavily cloaked with soil, and lose that soil much more readily if it is disturbed by cultivation. Furthermore, the rugged surface loses a much larger proportion of its total rainfall through run-off, and for that reason shows more quickly the undesirable effects of scanty precipitation. Hence the more uniform surface is more readily adapted to the production of the necessities of life and is at the same time capable of supplying larger quantities for each unit of area. Assuming, therefore, that the ultimate position of a nation depends mainly on its own ability to produce those things which come directly or indirectly from the soil, it may be said that the strength and permanency of a great nation lies mainly in its agricultural plains.
The ideal configuration of surface, judged with respect to the entire question of national evolution, would include enough diversity to stimulate variety in initiative, and at the same time, a sufficient extent of level area, to give permanent strength in supplying the primary wants of a large population. The United States may well be taken as the nearest approach to this ideal configuration. Estimated on this basis, the great nations of the future will be located on, and derive their strength from, the great plains areas of the world. For that reason one great nation may be expected to appear preeminent in the more favorably situated plains of each of the four major continents.
Productivity of the Soil and Climate.—The importance of the productivity of the soil and climate as one of the factors influencing national evolution has already been implied. Its further consideration, however, is necessary in order to indicate its variable application in the different stages of evolution. Meagerness of returns from a fair amount of human effort, or too great productivity with little or no regularity of effort, do not offer the fundamental conditions necessary for the development of nations, as indicated by the fact that no modern nation has risen to importance without having begun on an agricultural basis. No better evidence of that fact can be found than in the case of Britain and Germany, where to-day agriculture is decidedly secondary, but not very long ago was the main source of national strength. Yet however great importance the agricultural basis may be assumed to have as the foundation of national existence, it must be recognized in the study of individual nations, that beyond the early stages of evolution, the course of events, carrying the nation to the highest rank, may for a time reveal no significant control by the productivity of the soil in its own area.
The unrivaled British supremacy, in practically every respect, in the past century, the commercial and industrial conditions of Germany and of Japan at the present time, furnish examples of national develop-