A journey of four hundred and thirty miles can be made in any part of the United States, but in Turkey it takes as many days.

With every throb of the climatic pulse which we have felt in Central Asia,, the centre of civilisation has moved this way and that. Each throb has sent pain and decay to the lands whose day was done, life and vigour to those whose day was yet to be.

As a matter of fact, an ordinary desert supports a much greater variety of plants than does either a forest or a prairie.

Except on their southern borders the great northern forests are not good as a permanent home for man.

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.

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.

The whole history of life is a record of cycles.