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few exceptions, cannot survive. Conditions of temperature, such as obtain in the temperate zones, stimulate both the bodily and the mental faculties of humanity.^[1] Therefore they have resulted in a civilization fundamentally different from that of tropical regions.

1. “Every species of plant and animal has an optimum temperature at which it thrives most vigorously, and man is no exception. The optimum may vary a little from individual to individual, but not much. It is more likely to vary from one type of activity to another. For physical health among the white race as a whole, the best temperature is an average of 64° F for day and night together. In other words, people’s health and strength are greatest when the temperature drops to about 56° to 6o° at night, and rises to somewhere between 68° and 72° during the middle of the day. For mental activity the temperature is much lower than for physical, being an average of approximately 40°. In other words, people’s minds are most alert and inventive when the temperature falls to about freezing at night and rises to 45° or 50° by day.”—Huntington and Cushing’s Human Geography.