"We must not draw general conclusions from certain particular principles, though, in the main, true ones. We must not suppose that, because a man is a rational animal, he will therefore always act rationally; or, because he has such or such a predominant passion, that he will act invariably and consequentially in the pursuit of it. No. We are complicated machines: and though we have one main-spring, that gives motion to the whole, we have an infinity of little wheels, which, in their turns, retard, precipitate, and sometimes stop that motion."