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.