Aristotle says that “certain passions, if one makes a proper use of them, act as arms”: which would be true if, like weapons of war, they could be taken up or laid aside at the pleasure of their wielder. These arms, which Aristotle assigns to virtue, fight of their own accord, do not wait to be seized by the hand, and possess a man instead of being possessed by him. We have no need of external weapons, nature has equipped us sufficiently by giving us reason. She has bestowed this weapon upon us, which is strong, imperishable, and obedient to our will, not uncertain or capable of being turned against its master. Reason suffices by itself not merely to take thought for the future, but to manage our affairs: 21