Chapter 1

Things are called homonymous when they have only a name in common, while the account of being (ousia) corresponding to the name is different — as, for instance, both a man and a painted figure are called 'animal'. For these have only a name in common, while the account of being corresponding to the name is different; for if one were to give an account of what it is for each of them to be an animal, one would give an account proper to each.

Things are called synonymous when they have both the name in common and the same account of being corresponding to the name — as, for instance, both a man and an ox are called 'animal'. For a man and an ox are addressed by the common name 'animal', and the account of being is the same as well; for if one were to give the account of each — what it is for each of them to be an animal — one would give the same account.

Things are called paronymous when they get their name from something, differing from it in inflection — as, for instance, the grammarian from grammar, and the brave man from bravery.

Chapter 2

Of things that are said, some are said in combination, others without combination. Those in combination are, for example, 'man runs', 'man wins'; those without combination are, for example, 'man', 'ox', 'runs', 'wins'.

Of the things there are, some are said of a subject but are not in any subject: for example, man is said of a subject, the individual man, but is not in any subject. Some are in a subject but are not said of any subject (by 'in a subject' I mean what belongs in something, not as a part, and cannot exist separately from what it is in): for example, the particular knowledge of grammar is in a subject, the soul, but is not said of any subject; and the particular white is in a subject, the body (for every colour is in a body), but is not said of any subject.

Some are both said of a subject and in a subject: for example, knowledge is in a subject, the soul, and is said of a subject, the knowledge of grammar. And some are neither in a subject nor said of any subject: for example, the individual man and the individual horse; for nothing of this sort is either in a subject or said of a subject.

Speaking without qualification, things that are individual and numerically one are said of no subject; but nothing prevents some of them from being in a subject, for the particular knowledge of grammar is one of the things in a subject, yet is said of no subject.

Chapter 3

Whenever one thing is predicated of another as of a subject, all that is said of the predicate will also be said of the subject. For example, man is predicated of the individual man, and animal of man; hence animal will be predicated of the individual man as well — for the individual man is both a man and an animal.

Of things that belong to different genera and are not subordinate one to the other, the differentiae too are different in species: for example, of animal and of knowledge. The differentiae of animal are footed, two-footed, winged, aquatic, but none of these is a differentia of knowledge; for one knowledge does not differ from another by being two-footed.

But in the case of genera subordinate one to another nothing prevents them from having the same differentiae; for the higher genera are predicated of the genera beneath them, so that as many differentiae as the predicate has, so many will the subject have too.

Chapter 4

Of things said without any combination, each signifies either substance, or quantity, or quality, or a relative, or where, or when, or being in a position, or having, or acting, or being acted upon.

To speak in outline: substance is, for example, man, horse; quantity, for example, two cubits long, three cubits long; quality, for example, white, grammatical; a relative, for example, double, half, larger; where, for example, in the Lyceum, in the market-place; when, for example, yesterday, last year; being in a position, for example, is lying, is sitting; having, for example, has shoes on, is armed; acting, for example, cuts, burns; being acted upon, for example, is cut, is burned.

None of the things mentioned is said, just by itself, in any affirmation or denial; it is by the combining of these with one another that an affirmation or denial comes about. For every affirmation and denial seems to be either true or false, whereas of things said without any combination none is either true or false — for example, 'man', 'white', 'runs', 'wins'.

Chapter 5

A substance — that which is so called most strictly, primarily, and most of all — is that which is neither said of a subject nor in a subject: for example, the individual man or the individual horse. Secondary substances are those in which, as species, the things primarily called substances belong — these, and also the genera of these species. For example, the individual man belongs in a species, man, and animal is the genus of that species; hence these are called secondary substances, namely man and animal.

It is clear from what has been said that, of things said of a subject, both the name and the account must be predicated of the subject. For example, man is said of a subject, the individual man, and the name is indeed predicated of it — for you will predicate 'man' of the individual man. And the account of man will also be predicated of the individual man; for the individual man is both a man and an animal. Hence both the name and the account will be predicated of the subject.

But of things that are in a subject, in most cases neither the name nor the account is predicated of the subject. In some cases, however, nothing prevents the name from sometimes being predicated of the subject, though the account cannot be. For example, white, being in a subject, the body, is predicated of the subject (for a body is called white), but the account of white will never be predicated of the body.

All the other things are either said of the primary substances as subjects or are in them as subjects. This is clear from an examination of particular cases. For example, animal is predicated of man; hence animal will be predicated of the individual man as well — for if it were predicated of none of the individual men, it would not be predicated of man at all. Again, colour is in body; hence it is in an individual body as well — for if it were not in some individual body, it would not be in body at all. So all the other things are either said of the primary substances as subjects or are in them as subjects. Hence, if the primary substances did not exist, it would be impossible for any of the other things to exist.

Among the secondary substances the species is more a substance than the genus, for it is nearer to the primary substance. For if one gives an account of what the primary substance is, one will give a more informative and more appropriate account by giving the species than by giving the genus: for example, in giving an account of the individual man one would give a more informative account by giving 'man' than by giving 'animal'; for the one is more distinctive of the individual man, the other more general. And in giving an account of the individual tree one will give a more informative account by giving 'tree' than by giving 'plant'.

Again, it is because the primary substances are subjects for everything else, and because everything else is predicated of them or is in them, that they are for this reason called substances most of all. And as the primary substances stand to everything else, so the species stands to the genus; for the species is a subject for the genus — the genera are predicated of the species, but the species are not predicated of the genera in return. So on these grounds too the species is more a substance than the genus.

But among the species themselves, those that are not genera, none is more a substance than another; for you will give no more appropriate an account of the individual man by giving 'man' than you will of the individual horse by giving 'horse'. And in the same way, among the primary substances none is more a substance than another; for the individual man is no more a substance than the individual ox.

It is reasonable that, after the primary substances, of all the rest only the species and the genera should be called secondary substances; for of the things predicated these alone make clear the primary substance. For if one gives an account of what the individual man is, one will give an appropriate account by giving the species or the genus, and will make it more informative by giving 'man' than by giving 'animal'; but whatever else one gives, one will have given something foreign — for example, giving 'white' or 'runs' or anything of that kind. So it is reasonable that of all the rest these alone are called substances.

Again, the primary substances are called substances most strictly because they are subjects for everything else. And as the primary substances stand to everything else, so the species and the genera of the primary substances stand to all the rest; for all the rest are predicated of these. For you will call the individual man grammatical; hence you will call both man and animal grammatical. And it is the same in the other cases.

It is common to every substance not to be in a subject. For the primary substance is neither in a subject nor said of a subject. And as for the secondary substances, it is evident in this way too that they are not in a subject: man is said of a subject, the individual man, but is not in a subject — for man is not in the individual man. Similarly, animal too is said of a subject, the individual man, but animal is not in the individual man.

Further, of things that are in a subject, nothing prevents the name from sometimes being predicated of the subject, but the account cannot be. In the case of the secondary substances, however, both the account and the name are predicated of the subject; for you will predicate the account of man of the individual man, and likewise the account of animal. Hence substance is not among the things that are in a subject.

This, however, is not distinctive of substance; the differentia too is among the things not in a subject. For footed and two-footed are said of a subject, man, but are not in a subject — two-footed and footed are not in man. And the account of the differentia is predicated of whatever the differentia is said of: for example, if footed is said of man, the account of footed will also be predicated of man; for man is footed.

And let us not be disturbed by the parts of substances, as being in wholes as subjects, lest we be forced to say that they are not substances; for things in a subject were not meant in this way — as things belonging in something as parts.

It belongs to substances and to differentiae that everything called after them is so called synonymously. For all the predications from them are predicated either of the individuals or of the species. From a primary substance there is no predication, since it is said of no subject; but among the secondary substances the species is predicated of the individual, and the genus both of the species and of the individual. Similarly, the differentiae too are predicated both of the species and of the individuals. And the primary substances admit the account of the species and the account of the genera, and the species admits the account of the genus; for all that is said of the predicate will also be said of the subject. Similarly, the species and the individuals admit the account of the differentiae. But synonymous things were those with both the name in common and the same account; hence everything called after substances and after differentiae is so called synonymously.

Every substance seems to signify a certain 'this' (tode ti). In the case of the primary substances it is indisputable and true that each signifies a certain 'this'; for what is revealed is individual and numerically one. But in the case of the secondary substances, although from the form of the name it appears that they too signify a certain 'this' — when one says 'man' or 'animal' — this is not in fact true; rather, each signifies a certain qualification, since the subject is not one, as the primary substance is, but man and animal are said of many. Yet it does not signify a qualification simply, as white does; for white signifies nothing but a qualification, whereas the species and the genus mark off the qualification with respect to substance — they signify a substance of a certain qualification. But the marking off is broader in the case of the genus than in that of the species; for he who says 'animal' takes in more than he who says 'man'.

It also belongs to substances that there is nothing contrary to them. For what could be contrary to a primary substance — to the individual man, say, or to the individual animal? There is nothing contrary. Nor indeed is there anything contrary to man or to animal. This, however, is not distinctive of substance, but holds of many other things as well — for example, of quantity: there is nothing contrary to two cubits long or to three cubits long, nor to ten, nor to anything of that kind, unless someone were to say that many is contrary to few or great to small. But of definite quantities none is contrary to any.

Substance seems not to admit of the more and the less. I do not mean that one substance is not more a substance than another (for it has been said that it is), but that each substance is not called more or less that very thing which it is. For example, if this substance is a man, it will not be more or less a man — neither more so than itself nor more so than another; for one man is not more a man than another, as one white thing is more and less white than another, and one beautiful thing is called more and less beautiful than another. A thing is also called more and less than itself: a body that is white is called more white now than before, and one that is hot is called more and less hot. But substance is not called more and less at all; for a man is not called more a man now than before, nor is anything else that is a substance. Hence substance does not admit of the more and the less.

It seems most distinctive of substance that what is one and the same in number is able to receive contraries. In the case of everything else — of all the things that are not substances — one could not bring forward anything of this kind, anything which, being numerically one, is able to receive contraries. For example, colour, which is numerically one and the same, will not be white and black; nor will one and the same action, numerically one, be bad and good; and it is the same with all the other things that are not substances. But a substance, being one and the same in number, is able to receive contraries: for example, the individual man, being one and the same, becomes at one time pale and at another dark, and hot and cold, and bad and good.

Nothing of this kind appears in any other case, unless someone were to object and say that statements and beliefs are able to receive contraries. For the same statement seems to be both true and false: if, for example, the statement that someone is sitting is true, then, once he has stood up, this same statement will be false. And it is the same with belief: if one believed truly that someone is sitting, then, once he has stood up, one will believe falsely if one holds the same belief about him.

But even if one were to grant this, there is still a difference in the manner. For in the case of substances it is by themselves changing that they are able to receive contraries: what has become cold from hot has changed (for it has been altered), and what has become dark from pale, and good from bad; and similarly in the other cases, each of them is able to receive contraries by itself undergoing a change. Statements and beliefs, on the other hand, remain themselves altogether and in every way unmoved; it is because the actual thing moves that the contrary comes to hold of them. For the statement that someone is sitting remains the same, but when the thing has moved it is called at one time true and at another false. And it is the same with belief. Hence at least in respect of the manner it would be distinctive of substance to be able to receive contraries through a change in itself.

And if one were to grant these too — that statements and beliefs are able to receive contraries — this is not true. For statements and beliefs are said to be able to receive contraries not because they themselves receive anything, but because an affection has come about with respect to something else. For it is because the actual thing is or is not that a statement is said to be true or false, not because it is itself able to receive contraries. For, put simply, neither a statement nor a belief is moved by anything at all; so they would not be able to receive contraries, since no affection comes about in them. But a substance is said to be able to receive contraries because it itself receives the contraries: for it receives sickness and health, and paleness and darkness, and by itself receiving each of such things it is said to be able to receive contraries.

Hence it is distinctive of substance that, being one and the same in number, it is able to receive contraries through a change in itself. Let this much, then, be said about substance.