Gaius, Institutes, Book I. All nations who are ruled by law and customs make use partly of their own law, and partly of that which is common to all men. For whatever law any people has established for itself is peculiar to that State, and is called the Civil Law, as being the particular law of that State. But whatever natural reason has established among all men is equally observed by all mankind, and is called the Law of Nations, because it is the law which all nations employ.

Gaius, Institutes, Book I. All the law which We make use of relates either to persons, things, or actions.

Gaius, Institutes, Book I. The principal division of the law of persons is as follows, namely, that all men are either free or slaves.

Gaius, Institutes, Book I. Freedmen are those who are manumitted from lawful slavery.

Gaius, Institutes, Book I. Another division of persons follows according to law, some of whom are their own masters, and some are subject to the control of others. We shall now consider those who are subject to the control of others; for if we know who these persons are, we shall at once understand who those are that are their own masters. Let us then examine those who are under the control of others. 1Thus, slaves are under the power of their masters, and this power is derived from the Law of Nations, for we may perceive that among nearly all nations masters have the power of life and death over their slaves, and whatever is acquired by a slave is acquired by his master. 2But, at present, it is not permitted to any persons living under Roman dominion to be guilty of cruelty to their slaves which is atrocious, or without a cause recognized by the law. For, according to a Constitution of the Divine Antoninus, anyone who kills his slave without a cause shall be punished as severely as one who kills the slave of another; the inordinate severity of masters is also repressed by a Constitution of the same Emperor.

Gaius, Institutes, Book I. Our children also who are born in lawful marriage are under our control; which is a law peculiar to Roman citizens.

Gaius, Institutes, Book I. Adoption, generally speaking, takes place in two ways, either by the authority of the Emperor, or by the order of a magistrate. We adopt those by the authority of the Emperor who are their own masters; and this kind of adoption is called arrogation, because he who adopts is asked, that is, interrogated, whether he is willing that the party whom he is about to adopt shall be his lawful son; and he who is adopted is asked whether he suffers this to be done, We adopt by the order of a magistrate those who are under paternal control, whether they are in the first degree of children, such as son and daughter, or in one that is more remote, as grandson and granddaughter, and great-grandson and great-granddaughter. 1There is one thing common to both kinds of adoption, namely, that those who are incapable of procreation, as for instance, eunuchs, can adopt. 2Adoption effected through the Emperor is peculiar in that if anyone who has children under his control gives himself in arrogation, he himself is not only subjected to the authority of his adoptive father, but also his children and grandchildren pass under the control of the former.

Gaius, Institutes, Book I. He who has a son and a grandson under his control is at perfect liberty to release his son from his authority, and to retain it over his grandson; or, on the other hand, to retain his son under his control and to manumit his grandson; or to make both of them their own masters. We hold that the same rule applies to a great-grandson.

Gaius, Institutes, Book I. Those are agnates who are connected by relationship to persons of the male sex, just as cognates on the father’s side; as, for instance, a brother begotten by the same father, the son of a brother, or a grandson sprung from the latter; and, in like manner, a paternal uncle, the son of the latter, or a grandson descended from him.

Gaius, Institutes, Book II. Ad Dig. 1,8,1 pr.Windscheid: Lehrbuch des Pandektenrechts, 7. Aufl. 1891, Bd. I, § 146, Note 16.The principal division of Things is under two heads: for some of them belong to Divine and some to human law. Those which come under Divine law are, for instance, sacred and religious things. Sacred things are, for example, walls and gates, which, to a certain extent, are under Divine law. For what is subject to Divine law is not the property of anyone, and that indeed which belongs to human law is, for the most part, the property of someone, nevertheless, it may belong to none, for things belonging to an estate until an heir appears, are not the property of anyone. Again, those things that are under human law are either public or private. Those which are public are held to be the property of no one, and are considered to belong to the entire community, and those which are private belong to individuals. 1Moreover, some things are corporeal, and some are incorporeal. Those are corporeal which are tangible, as for instance land, slaves, clothing, gold, silver, as well as innumerable other articles. Those are incorporeal which cannot be touched as an usufruct, and obligations, in whatever way contracted. It does not matter if corporeal things are included in an estate, for the crops taken from land are corporeal, and whatever is owing to us through the obligation of another, is for the most part corporeal, as land, slaves, money; still, the right of succession, the right of use and enjoyment, and the right based upon an obligation are all incorporeal. To the same class belong all the rights of urban and rustic estates, which are designated as servitudes.

Gaius, Institutes, Book II. If we make inquiry as to whether a will is valid, we should first ascertain whether he who made it had the right to do so, and then, if he had, we should ascertain whether it was drawn up in accordance with the rules of the Civil Law.

Gaius, Institutes, Book II. Those also are included among posthumous children who, by succeeding to the place of proper heirs, through their birth become the lawful heirs of their parents. For instance, if I have a son, and a grandson or a granddaughter born to him, all under my control, as the son takes precedence by a degree in the succession, he alone has the right of a direct heir, even though the grandson and granddaughter, who are his children, are also under my control. If, however, my son should die during my lifetime, or, for any reason whatsoever, should be released from my control, the said grandson and granddaughter will take his place in the succession, and in that way their rights as direct heirs will be acquired, as it were by birth, but my testament will not be broken in this way, just as if I should appoint or disinherit my son as my heir; nor can I legally make a will in such a way that it will become necessary for me to appoint as heir, or disinherit my grandson or my granddaughter, unless my son having died during my lifetime, and my grandson or granddaughter having taken his place in the succession, should break the will, just as is done by birth; and this the Lex Julia Velleia provided for.

The Same, Institutes, Book II. Property is acquired for us not only by ourselves, but also by those whom we have in our power; as, for instance, by slaves in whom we have the usufruct, and also by freemen and slaves belonging to others of whom we have possession in good faith. Let us consider each of these cases in detail. 1Hence, anything which our slaves obtain by delivery, or which they stipulate for, or acquire in any other way whatsoever, is acquired by us; for he who is in the power of another can have nothing of his own. Therefore, if our slave is appointed an heir, he cannot enter upon the estate unless by our order, and if we order him to do so, the estate is acquired by us, just as if we ourselves had been appointed heirs. In conformity with this principle, a legacy also is acquired by us through our slave. 2Moreover, not only is ownership acquired for us by those whom we have under our control, but possession is also; for when they obtain possession of the property of anyone, we, ourselves, are considered to possess it; hence ownership is also acquired for us by long-continued possession. 3With reference to those slaves in whom we have only the usufruct, it has been decided that when they acquire anything through the use of our property, or by their own labor, it is acquired by us. If, however, they obtain anything by any other means, it will belong to him in whom the ownership of them is vested. Therefore, if a slave of this kind is appointed an heir, or if anything is bequeathed or given to him, it will not be acquired by me but for the owner of the property. 4The same rule which has been adopted with reference to an usufructuary is also applicable to one who is possessed by us in good faith, whether he is free, or a slave belonging to another; and is available in the case of a bona fide possessor. Hence, whatever is acquired in any other way than the two above mentioned will either belong to the person himself if he is free, or to his master if he is a slave. 5Still, where a bona fide possessor obtains a slave by usucaption, for the reason that, under these circumstances, he becomes his owner, he can acquire property through him in every way. An usufructuary, however, cannot acquire a slave by usucaption; first, because he does not actually possess him, but merely has the right of using and enjoying him; second, because he knows that the slave belongs to another.

The Same, Institutes, Book II. He does not commit a theft, for a theft cannot be committed without the intention of stealing. 1Anyone can also obtain possession of the land of another without violence, where it has become vacant through the neglect of the owner, or where the latter has died without leaving an heir, or has been absent for a long time.

The Same, Institutes, Book III. Obligations are contracted by consent in the case of purchases, sales, hirings, leases, partnerships, and mandates. 1We say that obligations are contracted by consent in these ways, because formality of words or writing is not essential; but it is sufficient for those who transact the business to consent. 2Hence such obligations may be contracted between parties who are absent, as, for instance, by letter or by messenger. 3Moreover, in contracts of this description each of the parties is bound to the others for whatever should be done, consistent with justice and good faith.