10 And this division of the civil law into two kinds seems not inappropriate, for it appears to have originated in the institutions of two states, namely Athens and Lacedaemon; it having been usual in the latter to commit to memory what was observed as law, while the Athenians observed only what they had made permanent in written statutes.
11 But the laws of nature, which are observed by all nations alike, are established, as it were, by divine providence, and remain ever fixed and immutable: but the municipal laws of each individual state are subject to frequent change, either by the tacit consent of the people, or by the subsequent enactment of another statute.
12 The whole of the law which we observe relates either to persons, or to things, or to actions. And first let us speak of persons: for it is useless to know the law without knowing the persons for whose sake it was established.
TITLE III. OF THE LAW OF PERSONS
In the law of persons, then, the first division is into free men and slaves.
1 Freedom, from which men are called free, is a man's natural power of doing what he pleases, so far as he is not prevented by force or law:
2 slavery is an institution of the law of nations, against nature subjecting one man to the dominion of another.
3 The name 'slave' is derived from the practice of generals to order the preservation and sale of captives, instead of killing them; hence they are also called mancipia, because they are taken from the enemy by the strong hand.
4 Slaves are either born so, their mothers being slaves themselves; or they become so, and this either by the law of nations, that is to say by capture in war, or by the civil law, as when a free man, over twenty years of age, collusively allows himself to be sold in order that he may share the purchase money.