A certain amount of cold seems to be essential to vigor of I body and mind, hut to produce this good effect it must not be excessive. The continual presence of snow and ice all through the year in the regions near the North Pole, by reducing all nature to one dead level of uniformity, stunts the mind, and, by refusing man variety of food and variety of bodily employment, stunts the body also. The long night, lasting for half the year, in which the inhabitants of the extreme north are condemned to unavoidable inaction, tends to produce the same effect. Thus it is that among the Greenlanders and Laplanders, though they live along the fringes of European civilization, no distant intellectual or moral progress marks the course of centuries. They show great skill in hunting the seal and in the few other industries that the intense cold allows them to practice: but their manners and customs are those of savages.
It is in the temperate countries of northern Europe that the beneficial effects of cold are most clearly 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 overcoming, 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. He has to build strong houses and procure thick clothes to keep him warm. To supply fuel for his fires, he must hew down tries and dig coal out of the bowels 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 neighborhood 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 livelorig day stretched out on the back ground beneath the shade of a tree. A very little fruit vegetable food is required to sustain life under such circumstances, and that little can be obtained without much execution from the bounteous earth.
We may recognize much the same difference between ourselves at different seasons of the years. As there is between human nature in the tropics and in temperate climates. In ho wealthier we are generally languid and inclined to take life easily: but when the cold season comes, we find that we are more inclining to vigorous exertion of our minds and bodies.