ironment tend to become worse, must live it out,
or die; the rabbit may move on in quest of a better. But, after all, the
swift-footed creatures are circumscribed in their wanderings. The first
large river almost inevitably bars their way, and certainly the first
salt sea becomes an impassable obstacle. Better locomotion may be
classed as one of the prime aims of the old natural selection; for in
that primordial day the race was to the swift as surely as the battle to
the strong. But man, already pre-eminent in the common domain because of
other faculties, was not content with the one form of locomotion afforded
by his lower limbs. He swam in the sea, and, still better, becoming
aware of the buoyant virtues of 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 least resistance,
and in virtue thereof, placed upon his craft rude keels which enabled him
to beat to windward in a seaway. As he excelled in these humble arts,
just so did he add to his power over his less progressive fellows and lay
the foundations for the first glimmering civilizations--crude they were
beyond conception, sporadic and ephemeral, but each formed a necessary
part of the groundwork upon which was to rise the mighty civilization of
our latter-day world.

Divorced from the general history of man's upward climb, it would seem
incredible that s