Fertile soil, level plains, easy passage across the mountains, coal, iron, and other metals imbedded in the rocks, and a stimulating climate, all shower their blessings upon man.

When you are bored of the plains, the secret passages to the mountains suddenly appear out of nowhere before you!

Again and again, to be sure, on the way to America, and under many other circumstances, man has passed through the most adverse climates and has survived, but he has flourished and waxed strong only in certain zones.

Geologists are rapidly becoming convinced that the mammals spread from their central Asian point of origin largely because of great variations in climate.

History in its broadest aspect is a record of man's migrations from one environment to another.

Curiously enough man's body and his mind appear to differ in their climatic adaptations.