People have observed that writers of physics, natural history, physiology, or chemistry were usually very tranquil, regular, and generally happy men; and that on the contrary, writers of politics, legislation, and even of morality were of a sad humor, melancholic, etc. Nothing is simpler: the first study nature, the second society: the first contemplate the work of a great being, the second limit their sight to the work of men. The results must be different.