Chapter 6

Division is the first section of the thing. Thus, for example, the animal is divided into rational and irrational. Redivision is the second section of the same thing. For example, the animal is redivided into apod, biped and quadruped—apod, as a fish; biped as a man or a bird; quadruped, as an ox, horse, or other such. Subdivision is the section of the already divided-off branch. For example, the animal is divided into rational and irrational, and then the rational into mortal and immortal. Now, the first thing is divided into two branches: the rational and the irrational. It is the division of one of these branches, namely, the division of the rational into mortal and immortal, that is subdivision. Division and redivision are not used in all cases. However, when everything is not covered by the first division—as, for example, when the animal is divided into rational and irrational, the biped is found both among the rational and the irrational animals—then of necessity we redivide, that is to say, we make a second division of the same thing, and we say: ‘The animal is divided into apod, biped, and quadruped.

For a similar reason, there are eight modes of division. Thus, everything that is divided is divided either according to itself, namely, according to substance, or according to accident. If it is divided according to itself, then it is either as a thing or as a term. If it is divided as a thing, then it is either as genus into species, as when you divide the animal into rational and irrational, or as species into individuals, as man into Peter and Paul and all other individual men, or as a whole into parts. This last division is twofold, being either into like or unlike parts. Now, a thing is of like parts whenever its sections admit of the name and the definition of the whole and of each other. For instance, when flesh is divided into several pieces, each portion is called flesh and admits of the definition of flesh. On the contrary, the thing is of unlike parts whenever the part cut off will not admit either of the name or of the definition, whether of the whole or of the parts. Thus, should you divide Socrates into hands and feet and head, the foot cut off from Socrates would neither be called Socrates nor his head, nor would it admit of the definition either of Socrates or of his head. Or division may be as that of an equivo