Man could not stay there forever. He was bound to spread to new regions, partly because of his innate migratory tendency and partly because of Nature's stern urgency.

Thus the races, though alike in their physical response to climate, may possibly be different in their mental response because they have approached America by different paths.

From first to last the civilization of America has been bound up with its physical environment.

Although mountains may guide migrations, the plains are the regions where people dwell in greatest numbers.

Year by year we are learning that in this restless, strenuous American life of ours vacations are essential.

America forms the longest and straightest bone in the earth's skeleton.

The Negro, however, has been tested on an extensive scale.