How shall we proceed to define an object or a term? Aristotle answers that every good definition has two parts, stands on two solid feet: first, it assigns the object in question to a class or group whose general characteristics are also its own—so man is, first of all, an animal; and secondly, it indicates wherein the object differs from all the other members in its class—so man, in the Aristotelian system, is a rational animal, his “specific difference” is that unlike
