wood, learned to navigate its surface. Likewise, from among the land animals he chose the more likely to bear him and his burdens. The next step was the domestication of these useful aids. Here, in its organic significance, natural selection ceased to concern itself with locomotion. Man had displayed his impatience at her tedious methods and his own superiority in the hastening of affairs. Thenceforth he must depend upon himself, and faster-swimming or faster-running men ceased to be bred. The one, half-amphibian, breasting the water with muscular arms, could not hope to overtake or escape an enemy who propelled a fire-hollowed tree trunk by means of a wooden paddle; nor could the other, trusting to his own nimbleness, compete with a foe who careered wildly across the plain on the back of a half-broken stallion.
So, in that dim day, man took upon himself the task of increasing his dominion over space and time, and right nobly has he acquitted himself. Because of it he became a road builder and a bridge builder; likewise, he wove clumsy sails of rush and matting. At a very remote period he must also have recognized that force moves along the line of
