But whether any person is such by nature, and whether it is advantageous and just for any one to be a slave or no, or whether all slavery is contrary to nature, shall be considered hereafter; not that it is difficult to determine it upon general principles, or to understand it from matters of fact; for that some should govern, and others be governed, is not only necessary but useful, and from the hour of their birth some are marked out for those purposes, and others for the other, and there are many species of both sorts. And the better those are who are governed the better also is the government, as for instance of man, rather than the brute creation: for the more excellent the materials are with which the work is finished, the more excellent certainly is the work; and wherever there is a governor and a governed, there certainly is some work produced; for whatsoever is composed of many parts, which jointly become one, whether conjunct or separate, evidently show the marks of governing and governed; and this is true of every living thing in all nature; nay, even in some things which partake not of life, as in music; but this probably would be a disquisition too foreign to our present purpose. Every living thing in the first place is composed of soul and body, of these the one is by nature the governor, the other the governed; now if we would know what is natural, we ought to search for it in those subjects in which nature appears most perfect, and not in those which are corrupted; we should therefore examine into a man who is most perfectly formed both in soul and body, in whom this is evident, for in the depraved and vicious the body seems [1254b] to rule rather than the soul, on account of their being corrupt and contrary to nature. We may then, as we affirm, perceive in an animal the first principles of herile and political government; for the soul governs the body as the master governs his slave; the mind governs the appetite with a political or a kingly power, which shows that it is both natural and advantageous that the body should be governed by the soul, and the pathetic part by the mind, and that part which is possessed of reason; but to have no ruling power, or an improper one, is hurtful to all; and this holds true not only of man, but of other animals also, for tame animals are naturally better than wild ones, and it is advantageous that both should be under subjection to man; for this is productive of their common safety: so is it naturally with the male and the female; the one is superior, the other inferior; the one governs, the other is governed; and the same rule must necessarily hold good with respect to all mankind. Those men therefore who are as much inferior to others as the body is to the soul, are to be thus disposed of, as the proper use of them is their bodies, in which their excellence consists; and if what I have said be true, they are slaves by nature, and it is advantageous to them to be always under government. He then is by nature formed a slave who is qualified to become the chattel of another person, and on that account is so, and who has just reason enough to know that there is such a faculty, without being indued with the use of it; for other animals have no perception of reason, but are entirely guided by appetite, and indeed they vary very little in their use from each other; for the advantage which we receive, both from slaves and tame animals, arises from their bodily strength administering to our necessities; for it is the intention of nature to make the bodies of slaves and freemen different from each other, that the one should be robust for their necessary purposes, the others erect, useless indeed for what slaves are employed in, but fit for civil life, which is divided into the duties of war and peace; though these rules do not always take place, for slaves have sometimes the bodies of freemen, sometimes the souls; if then it is evident that if some bodies are as much more excellent than others as the statues of the gods excel the human form, every one will allow that the inferior ought to be slaves to the superior; and if this is true with respect to the body, it is still juster to determine in the same manner, when we consider the soul; though it is not so easy to perceive the beauty of [1255a] the soul as it is of the body. Since then some men are slaves by nature, and others are freemen, it is clear that where slavery is advantageous to any one, then it is just to make him a slave.
Whether anyone is a slave by nature remains to be considered. So does whether slavery is beneficial and just for anyone, or whether all slavery is contrary to nature. These questions are not difficult to settle through general principles or the facts. For some to rule and others to be ruled is not only necessary but useful. From birth, some are marked out to rule and others to be ruled. There are many kinds of rulers and subjects. The better those being ruled are, the better the government is. Governing human beings, for example, is better than governing animals. For the better the materials used in a work, the better the finished work will certainly be. And wherever someone rules and someone is ruled, some work is certainly produced. Anything made of many parts that together form a whole clearly shows a ruling element and a ruled element. This holds whether the parts are joined together or separate. It is true of every living thing in nature. Such a relationship exists even in some things without life, such as music. But exploring that subject would probably take us too far from our present purpose. Every living thing consists, first of all, of soul and body. Of these, the soul naturally rules and the body is ruled. To understand what is natural, we should examine beings in which nature appears most perfect, not those that are corrupted. We should therefore examine a man whose soul and body are most perfectly formed. In such a man, the natural relationship is clear. In depraved and vicious people, however, the body seems [1254b] to rule the soul. This is because their condition is corrupt and contrary to nature. In a living creature, then, we can observe the basic principles of rule by a master and political rule. The soul rules the body as a master rules his slave. The mind rules desire with political or royal authority. This shows that the soul's rule over the body is both natural and beneficial. The same holds for the rule of the mind, the part possessing reason, over the emotions. But having no ruling power, or the wrong one, harms all these parts. This principle applies not only to human beings but also to other animals. For tame animals are naturally better than wild ones. It benefits both kinds to be subject to human beings, because this ensures their common safety. The same natural relationship holds between male and female. The male is superior and the female inferior. The male rules and the female is ruled. The same rule must necessarily apply to all humanity. Some men, then, are as inferior to others as the body is to the soul. These men should be treated accordingly, since their proper use lies in their bodies, where their excellence lies. If what I have said is true, they are slaves by nature. It benefits them to remain under rule at all times. A natural slave, then, is someone fitted to become another person's property, and who therefore belongs to another. He has enough reason to recognize that faculty, but does not possess the ability to use it. Other animals have no awareness of reason and are guided entirely by appetite. Indeed, slaves and tame animals differ very little in their usefulness. Both benefit us by using their bodily strength to meet our needs. For nature intends the bodies of slaves and free men to differ. Slaves are meant to have strong bodies for necessary tasks. Free men are meant to stand upright. Their bodies are unsuited to slaves' work but suited to civic life, with its duties of war and peace. Yet these distinctions do not always hold. Slaves sometimes have the bodies of free men, and sometimes their souls. Suppose, then, that some bodies clearly surpassed others as much as statues of the gods surpass the human form. Everyone would agree that those with inferior bodies ought to be slaves to those with superior bodies. If this is true of the body, the same judgment is even more just when applied to the soul. Yet the beauty of [1255a] the soul is harder to recognize than the beauty of the body. Since some men are slaves by nature and others are free, the conclusion is clear. Where slavery benefits someone, it is just to make him a slave.