Глава XVII. О сказуемом, отвечающем на вопрос: что есть предмет? и каков предмет?

A predicate that answers the question: what is an object? different from the predicate answering the question: what is the object? A predicate of the first kind occurs, for example, when, answering the question: what is an object? we say: animal. A predicate of the second kind occurs when, answering the question: what kind of animal, we say: rational, mortal. Thus, both genus and species answer the question: what is the object. And hypostasis does not express what the object is, nor what it is, but who. For, answering the question who this is, we say: Peter. Then, answering the question what kind of person is, we say: tall, for example, or small. It should be noted that about objects that differ in nature, they say: one and the other. So we say: man is one thing (αλλο), and a horse is another (αλλο): different, of course, by nature, for man is one species, and a horse another. About objects that differ only in numerical order, they say: one and the other. So we say: Peter is one (αλλος), and Paul is another (αλλος). But we cannot say that Peter is one thing (αλλο), and Paul is another (αλλο), otherwise we would be lying, for by nature they are one, but by number they do not constitute one. It should be noted that substance is said to be “one thing” (αλλο). The same must be said about significant differences. But they say about accidents: one or another quality (αλλοιον), because essential differences are considered in relation to the species or nature and form it, while accidents are considered in relation to the individual, since accidents constitute a hypostasis. Therefore, a man is one thing and a horse is another. Peter is of one quality (αλλοιος) and one (αλλος), and Paul of another quality (αλλοιος) and another (αλλος). But every difference, essential and inessential, posits a difference (ἑτεροιον ποιει) for by difference one must understand both the other in nature and the other in terms of quality (αλλοιον). Nature means what an object is, and hypostasis means who it is or what it is; every difference means what the object is. You might be interested in: