Page:Popular Science Monthly Volume 81.djvu/557

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IFE implies surplus energy. No organism can exist for any appreciable period without experiencing the fact that its environment is more favorable or more hostile to its life-activities at one time than at another time. Strength that just suffices to resist some special stress thus yields a surplus when that stress is over. Protozoa and men alike are subject to vicissitudes. At times they barely manage to survive. Again their energy exceeds their needs.

How variations increasing surplus energy are caused no man has definitely shown, though Metchnikoff may yet succeed in proving why the surplus disappears. We merely know that surplus does exist in varying degrees and that its rise and fall depend on measurable facts. We know, too, that the greater the surplus the greater the freedom men have to pursue the higher ends of life or, if they choose, the lower.

The fact that surplus energy exists and that important consequences result therefrom has been often emphasized. Shiller presented the idea in his discussion of esthetics a century ago, and even Groos, though severely criticizing Spencer for connecting the idea of imitation with the overflow of energy, admits the presence of surplus energy to be "the conditio sine quâ non which permits the instincts to be so augmented that finally. . . they. . . permit indulgence in merely sportive acts." Patten has even proclaimed a "new basis of civilization" upon the assumption that a social surplus now exists whereby a "pain economy" has been replaced by a "pleasure economy." These writers, however, and others who have dealt with the subject appear to have been interested primarily in demonstrating that certain phenomena or consequences result from an existing surplus. To a limited extent only do they attempt to show upon what conditions the amount of surplus energy in any given case depends. The way appears open, therefore, for a discussion of the clearly marked stages in the increases of surplus energy which have taken place in the evolution of the higher from the lower forms of life and in the evolution of man himself. Such a discussion may be expected to throw light upon at least three problems of more than academic interest. These are the questions: why man in a comparatively brief period of time (as reckoned in geology) has far outstripped competitors; why sociologists should consider psychological