It is in the temperate countries of northern Europe that the beneficial effects of cold are most manifest. A cold climate seems to stimulate energy by acting as an obstacle. In the face of an insuperable obstacle our energies are numbed by despair; the total absence of obstacles, on the other hand leaves no room for the exercise and training of energy; but a struggle against difficulties that we have a fair hope of over-coming, calls into active operation all our powers. In like manner, while intense cold numbs human energies, and a hot climate affords little motive for exertion, moderate cold seems to have a bracing effect on the human race. In a moderately cold climate man is engaged in an arduous, but no hopeless struggles and with the inclemency of the weather. He has to build strong houses and procure thick clothes to keep himself warm. To supply fuel for his fires, he must hew down trees and dig coal out of the earth. In the open air, unless he moves quickly, he will suffer pain from the biting wind. Finally, in order to replenish the expenditure of bodily tissue caused by his necessary exertions, he has to procure for himself plenty of nourishing food.
Quite different is the lot of man in the tropics. In the neighbourhood of the equator there is little need of clothes or fire, and it is possible with perfect comfort and no danger to health, to pass the livelong day stretched out on the bare ground beneath the shade of a tree. A very little fruit or vegetable food is required to sustain life under such circumstances, and that little can be obtained without much exertion from the bounteous earth.
We may recognize must the same difference between ourselves at different seasons of the year, as there is between human nature in the tropics and in temperate climes. In hot weather we are generally languid and inclined to take life easily; but when the cold season comes, we find that we are more inclined to vigorous exertion of our minds and bodies.
