CATEGORIES.

Relation is, for example, "double," "half," or "greater." Place is, for example, "in the Lyceum" or "in the marketplace." Time is, for example, "yesterday" or "last year." Position is, for example, "lying down" or "sitting." State is, for example, "wearing shoes" or "being armed." Acting is, for example, "cutting" or "burning." Being affected is, for example, "being cut" or "being burned." Each of these, taken by itself, is not said in any affirmation or negation. Affirmation or negation arises from their combination. Every affirmation and negation seems to be either true or false, but none of the things said without combination are true or false, such as "human," "white," "runs," or "wins."

5 Substance is that which is most properly, primarily, and especially so-called, which is neither predicated of a subject nor is in any subject, such as an individual human or an individual horse. Secondary substances are those in which the primary substances are included, as well as the kinds of these kinds. For example, an individual human is included in the species "human," and the genus of this species is "animal." These are therefore called secondary substances, such as "human" and "animal." It is clear from what has been said that for things predicated of a subject, it is necessary that both the name and the definition of the subject are predicated of it. For example, "human" is predicated of an individual human, and its name is predicated. You will predicate "human" of an individual human, and the definition of "human" will also be predicated of the individual human. For that individual human is both a human and an animal. Thus, both the name and the definition will be predicated of the subject. For things that are in a subject, in most cases, neither the name nor the definition is predicated of the subject. But in some cases, nothing prevents the name from being predicated of the subject, although the definition is impossible to predicate. For example, "white," being in a body as a subject, is predicated of the subject (for a body is called white), but the definition of "white" will never be predicated of a body. All other things are either predicated of primary substances as subjects or are in those subjects. This is clear from examining individual cases. For example, "animal" is predicated of "human." Therefore, it will also be predicated of an individual human. For if it is not predicated of any individual human, it is not predicated of "human" at all. Again, "color" is in a body; therefore, it is also in an individual body. For if it were not in any of the particulars, it would not be in a body at all. Thus, all other things are either predicated of primary substances as subjects or are in those subjects. Therefore, if the primary substances did not exist, it would be impossible for anything else to exist.

Of secondary substances, the species is more of a substance than the genus; for it is closer to the primary substance. If one were to define the primary substance, one would provide a more informative and appropriate definition by giving the species than by giving the genus. For example, if one defines an individual human, one would provide a more informative definition by saying "human" than by saying "animal," for the former is more specific to the individual human, while the latter is more general. Furthermore, primary substances are most properly called substances because they serve as subjects for all other things, and all other things are predicated of them or exist in them. And as primary substances relate to all other things, so the species relates to the genus; for the species serves as a subject for the genus. For the genera are predicated of the species, but the species are not predicated of the genera in return. Thus, from this, the species is more of a substance than the genus. Of the species themselves, none is more of a substance than another; for you will not provide a more appropriate definition for an individual human by saying "human" than you would for an individual horse by saying "horse." Similarly, among primary substances, none is more of a substance than another; for an individual human is no more a substance than an individual ox.

Naturally, after the primary substances, only the species and genera are called secondary substances, for they alone represent the primary substance among the predicates. For if one were to define an individual human, one would provide an appropriate and informative definition by giving the species or genus, saying "human" or "animal," rather than other things. Any other thing one might offer would be external, such as saying "white," "running," or anything similar. Thus, it is reasonable that only these are called substances. Furthermore, primary substances are called substances most properly because they serve as subjects for all other things.