that, as the geographical horizon of the known world has widened from
gray antiquity to the present, societies and states have expanded their
territorial and economic scope; that they have grown not only in the
number of their square miles and in the geographical range of their
international intercourse, but in national efficiency, power, and
permanence, and especially in that intellectual force which feeds upon
the nutritious food of wide comparisons. Every great movement which has
widened the geographical outlook of a people, such as the Crusades in
the Middle Ages, or the colonization of the Americas, has applied an
intellectual and economic stimulus. The expanding field of advancing
history has therefore been an essential concomitant and at the same time
a driving force in the progress of every people and of the world.

[Sidenote: Man's increasing dependence upon nature.]

Since progress in civilization involves an increasing exploitation of
natural advantages and the development of closer relations between a
land and its people, it is an erroneous idea that man tends to
emancipate himself more and more from the control of the natural
conditions forming at once the foundation and environment of his
activities. On the contrary, he multiplies his dependencies upon
nature;[124] but while increasing their sum total, he diminishes the
force of each. There lies the gist of the matter. As his bonds become
more numerous, they become also more elastic. Civilization has
lengthened his leash and padded his collar, so that it does not gall;
but the leash is never slipped. The Delaware Indians depended upon the
forests alone for fuel. A citizen of Pennsylvania, occupying the former
Delaware tract, has the choice of wood, hard or soft coal, coke,
petroleum, natural gas, or manufactured gas. Does this mean
emancipation? By no means. For while fuel was a necessity to the Indian