Evolution is a struggle for, and a conquest of, space; for evolution,
as the word implies, is a _drawing out_ of what is inherent from
latency into objective reality, or in other words into spatial--and
temporal--extension.
This struggle for space, by means of which the birth and growth of
organisms is achieved, is the very texture of life, the plot of
every drama. Cells subdivide; micro-organisms war on one another;
plants contend for soil, light, moisture; flowers cunningly suborn
the bee to bring about their nuptials; animals wage deadly warfare
in their rivalry to bring more hungry animals into a space-hungry
world. Man is not exempt from this law of the jungle. Nations
intrigue and fight for land--of which wealth is only the symbol--and
a nation's puissance is measured by its power to push forward into
the territory of its neighbor. The self-same impulse drives the
individual. One measure of the difference between men in the matter
of efficiency is the amount of space each can command: one has a
house and grounds in some locality where every square inch has an
appreciable value; another some fractional part of a lodging house
in the slums. When this bloodless, but none the less deadly, contest
for space becomes acute, as in the congested quarters of great cities,
man's ingenuity is taxed to devise effective ways of augmenting his
_space-potency_, and he expands in a vertical direction. This
third-dimensional extension, typified in the tunnel and in the
skyscraper, is but the latest phase of a conquest of space which
began with the line of the pioneer's trail through an untracked
wilderness.