Chapter 1: A General Idea

If it is true that the mind's character and the heart's passions would be extremely different in differing climates, the laws ought to be relative both to the difference of these passions and to the difference of these characters.

Chapter 2: How Much Men Are Different in Differing Climates

Cold air (aa) tightens extremities of the exterior fibers of our body; that increases their energy and encourages the return of blood from the extremities to the heart. It diminishes the length (b)b of those same fibers; therefore it thereby increases their force. Hot air, on the other hand, releases the extremities of the fibers, and lengthens them. Therefore, it diminishes their strength and energy.

Therefore one has greater vigor in cold climates. The heart's activity and the reaction of the fiber's extremities perform better, the fluids are in better equilibrium, the blood is more impelled toward the heart, and reciprocally the heart has greater power. That greater strength ought to produce many effects; for example, more confidence in oneself, which is to say, more courage; more understanding of one's superiority, which is to say, less desire for vengeance; greater opinion of one's safety, which is to say, more candor, and less suspicion, policy and ruse. In sum, this ought to produce quite different characters. Place a man in a hot and closed place, and he will suffer, for the reasons I’m happening to relate, an intense heart failure. If, under that circumstance, one approaches him to propose a bold deed, I believe that one will find him very little open to it. His present weakness will cast discouragement over his soul. He will fear everything, for he will feel that he can do nothing. The peoples from hot countries are timid, as the elderly are. Those from cold countries are courageous, as youths are. If we pay attention to the last (c) wars, which are those which we have most beneath our eyes, and in which we are better able to see certain slight effects, imperceptible from afar, we will well sense that the peoples of the north, transferred into southerly countries (d), have not performed such beautiful actions there as their compatriots who, fighting in their own climate, profited from their entire courage.

The strength of northern people's fibers causes [the effect] that the heaviest nutrients are extracted from the foods.