Chapter 11

The contrary of a good is necessarily a bad. This is clear by induction from particular cases: to health, sickness; to courage, cowardice; and likewise in the other cases. But the contrary of a bad is sometimes a good and sometimes a bad. For to deficiency, which is a bad, excess is contrary, and it too is a bad; yet equally the mean is contrary to each of them, and it is a good. Such cases, however, one would find in only a few instances; in most cases the contrary of a bad is always a good.

Again, in the case of contraries it is not necessary, if one of them exists, that the other should exist too. For if all were healthy there would be health but not sickness; and likewise, if all things were white there would be whiteness but not blackness. Again, if Socrates' being healthy is contrary to Socrates' being sick, and it is not possible for both to belong at the same time to the same thing, then it would not be possible, when one of the contraries exists, for the remaining one to exist as well; for if Socrates' being healthy exists, Socrates' being sick will not.

It is clear, too, that contraries naturally come to be in connection with the same thing, whether the same in species or in genus. For sickness and health naturally come to be in the body of an animal, whiteness and blackness in body without qualification, and justice and injustice in the soul of a man.

Further, all contraries must either be in the same genus, or in contrary genera, or themselves be genera. For white and black are in the same genus (since colour is their genus), while justice and injustice are in contrary genera (since the genus of the one is virtue and of the other vice); but good and bad are not in a genus — rather they themselves happen to be genera of certain things.

Chapter 12

One thing is called prior to another in four ways. First and most strictly, in respect of time, in which sense one thing is called older or more ancient than another; for it is because the time is longer that a thing is called older and more ancient.

Secondly, what does not reciprocate as to implication of existence. For example, one is prior to two: for if there are two it follows at once that there is one, but if there is one it is not necessary that there should be two, so that from the one the implication of the other's existence does not reciprocate. And that from which the implication of existence does not reciprocate is thought to be prior.

Thirdly, a thing is called prior in respect of some order, as with the sciences and with speeches. For in the demonstrative sciences there is a prior and a posterior in order (the elements are prior in order to the geometrical proofs, and in grammar the letters are prior to the syllables), and likewise with speeches, for the introduction is prior in order to the narrative.

Further, besides the ways mentioned, what is better and more valued is thought to be prior by nature. Ordinary people are indeed accustomed to say of those they hold in higher honour and love more that these come first with them. This is pretty well the least proper of the ways.

These, then, are about all the ways in which the prior is spoken of. Yet besides those mentioned there would seem to be another way of being prior. For of things that do reciprocate as to implication of existence, that which is in any way the cause of the other's existence might reasonably be called prior by nature. And that there are cases of this sort is clear. For a man's existing reciprocates, as to implication of existence, with the true statement about him. For if there is a man, the statement by which we say that there is a man is true. And it does reciprocate: for if the statement by which we say that there is a man is true, then there is a man. But the true statement is in no way the cause of the thing's existing, whereas the thing does seem in some way to be the cause of the statement's being true; for it is because the thing is or is not that the statement is called true or false.

Hence one thing is called prior to another in five ways.

Chapter 13

Things are called simultaneous without qualification and most strictly when their coming to be is at the same time; for neither of them is prior or posterior to the other. These are called simultaneous in respect of time.

Those things are simultaneous by nature which reciprocate as to implication of existence, provided that neither is in any way the cause of the other's existence — as with the double and the half. For these do reciprocate (since if there is a double there is a half, and if there is a half there is a double), yet neither is the cause of the other's existence.

Also called simultaneous by nature are those things from the same genus which are set over against one another in a division. Things are said to be set over against one another in this way when they fall under the same division, as the winged is set against the footed and the water-dwelling; for these are set over against one another as members of a division of the same genus. For animal is divided into these — into the winged, the footed and the water-dwelling — and none of these is prior or posterior; rather things of this sort are thought to be simultaneous by nature. And each of these might in turn be divided into species: the footed, the winged and the water-dwelling. Those too, then, will be simultaneous by nature, all that belong to the same genus and fall under the same division.

But genera are always prior to their species, for they do not reciprocate as to implication of existence: if there is a water-dweller there is an animal, but if there is an animal it is not necessary that there should be a water-dweller.

We call simultaneous by nature, then, those things which reciprocate as to implication of existence, provided that neither is in any way the cause of the other's existence, and also those things from the same genus that are set over against one another in a division; and simultaneous without qualification, those whose coming to be is at the same time.

Chapter 14

There are six kinds of change: generation, destruction, increase, diminution, alteration, and change of place. That the other changes are different from one another is evident; for generation is not destruction, nor is increase diminution, nor is it change of place, and so likewise with the rest. But in the case of alteration there is some difficulty, whether it may not be necessary for what is altering to be altering in virtue of one of the remaining changes.

This, however, is not true. For it happens that we are altered in respect of practically all the affections, or of most of them, without partaking in any of the other changes; for what is changed in respect of an affection need not increase, nor need it diminish, and likewise with the rest. Hence alteration would be a change distinct from the others. For if it were the same, what is altering would have to be increasing or diminishing straight away, or one of the other changes would have to follow upon it; but this is not necessary. And in the same way what is increasing, or is changing with some other change, would have to be altering; but there are some things that increase without altering — a square, for instance, when a gnomon is placed round it, has increased, yet has become nothing different in quality; and likewise in the other such cases. So the changes would be different from one another.

Change in general has rest as its contrary, while the particular changes have particular contraries: destruction is contrary to generation, diminution to increase, and rest in place to change of place. But what seems most of all to be opposed is change towards the contrary place: upward change to downward change, and downward change to upward.

For the one remaining change of those set out it is not easy to state what its contrary is; it seems to have nothing contrary to it, unless here too one were to oppose to it rest in respect of quality, or change to the contrary quality — just as, with change of place, one opposed rest in place, or change to the contrary place. For alteration is change in respect of quality. So to change in respect of quality there will be opposed rest in respect of quality, or change to the contrary quality, as becoming white is opposed to becoming black; for a thing alters when a change to the contraries of the quality takes place.

Chapter 15

Having is spoken of in a number of ways. It may be as a state and a condition, or as some other quality; for we are said to have a certain kind of knowledge, and to have virtue.

Or as a quantity, as with the size a man happens to have; for he is said to have a size of three cubits, or of four.

Or as the things that are about the body, such as a cloak or a tunic. Or as something on a part of the body, as a ring on the hand. Or as a part, as a hand or a foot.

Or as in a container, as the grain-measure (medimnos) has the wheat, or the jar the wine; for the jar is said to have wine, and the grain-measure wheat. All these, then, are said to have in the sense of being in a container.

Or as a possession; for we are said to have a house or a field.

A man is also said to have a wife, and the wife a husband. But the way of having just mentioned seems to be the most alien of all; for by "having a wife" we signify nothing other than that he lives together with her.

Perhaps some other ways of having might yet come to light, but practically all those that are customarily spoken of have now been enumerated.