Ulpianus, Book I, Institutes. Those who apply themselves to the study of law should know, in the first place, from whence the science is derived. The law obtains its name from justice; for (as Celsus elegantly says), law is the art of knowing what is good and just. 1Anyone may properly call us the priests of this art, for we cultivate justice and profess to know what is good and equitable, dividing right from wrong, and distinguishing what is lawful from what is unlawful; desiring to make men good through fear of punishment, but also by the encouragement of reward; aiming (if I am not mistaken) at a true, and not a pretended philosophy. 2Of this subject there are two divisions, public and private law. Public law is that which has reference to the administration of the Roman government; private law is that which concerns the interests of individuals; for there are some things which are useful to the public, and others which are of benefit to private persons. Public law has reference to sacred ceremonies, and to the duties of priests and magistrates. Private law is threefold in its nature, for it is derived either from natural precepts, from those of nations, or from those of the Civil Law. 3Natural law is that which nature teaches to all animals, for this law is not peculiar to the human race, but affects all creatures which deduce their origin from the sea or the land, and it is also common to birds. From it proceeds the union of male and female which we designate as marriage; hence also arises the procreation of children and the bringing up of the same; for we see that all animals, and even wild beasts, appear to be acquainted with this law. 4The Law of Nations is that used by the human race, and it is easy to understand that it differs from natural law, for the reason that the latter is common to all animals, while the former only concerns men in their relations to one another:

Ulpianus, Institutes, Book I. Manumissions also, are part of the Law of Nations, for manumission is dismissal by the hand, that is to say the bestowal of freedom; for as long as anyone is in servitude he is subject to the hand and to authority, but, once manumitted, he is liberated from that authority. This takes its origin from the Law of Nations; since, according to natural law all persons were born free, and manumission was not known, as slavery itself was unknown; but after slavery was admitted by the Law of Nations, the benefit of manumission followed, and while men were designated by one natural name there arose three different kinds under the Law of Nations, that is to say freemen, and, in distinction to them, slaves, and as a third class, freedmen, or those who had ceased to be slaves.

Ulpianus, Institutes, Book I. The Civil Law is something which is not entirely different from natural law or that of Nations, nor is it in everything subservient to it; and therefore when we add or take anything from the Common Law we constitute a separate law, that is the Civil Law. 1This our law then is established either by writing, or without it, as among the Greeks “twn nomwn oi men eggrafoi oi de agrafoi”, that is to say, some laws are in writing and others are not.

Ulpianus, Institutes, Book I. Whatever the Emperor has decreed has the force of law; since by a Royal ordinance which was passed concerning his sovereignty, the people conferred upon him all their own authority and power. 1Therefore, everything which the Emperor decrees by a letter over his signature, whether he decided after examining it or did so without judicial consideration or ordered it by means of an edict, has the force of law; and these are what we generally designate constitutions. 2Among the latter there are some which are special, and are not to be employed as precedents; for whatever the Emperor has granted to anyone as a reward of merit, or where he inflicts a penalty, or relieves a person in an unusual way, this does not extend beyond the party in question.

Ulpianus, Institutes, Book I. Certain Roman citizens are fathers of families, others are sons of families, some are mothers of families, others again are daughters of families. Those are fathers of families who are their own masters, whether they have arrived at puberty or not; in the same manner those who are under the control of others are either the mothers of families, or the sons or daughters of families. For any child who is born of me and my wife is under my control; also a child born of my son and his wife, that is to say my grandson and granddaughter, are also under my control, as well as my great-grandson and great-granddaughter, and so on with reference to other descendants.

Ulpianus, Institutes, Book I. It is held that the husband can also act when he has a right to recover anything from his wife; for instance, if he has lost money on her account either because he has expended it for her, or paid it out under her direction. But if he has not lost anything thus far, for example, where he is conditionally liable, he is not yet considered qualified to proceed.

Ulpianus, Institutes, Book I. A precarious tenure is one by which a party petitioning for it is permitted to enjoy the use of property as long as he who grants him permission suffers him to do so. 1This species of generosity is derived from the Law of Nations. 2It differs from a donation, in that he who makes a donation has no intention of receiving the property again; but he who grants anything by a precarious tenure does so with the expectation of resuming control of the property when he chooses to release it from the tenure. 3It also resembles a loan for use, for he who lends property in this manner does so in such a way as not to render the article loaned the property of the person who receives it, but he only permits him to make use of it.

Ulpianus, Institutes, Book I. Enemies are those against whom the Roman people have publicly declared war, or who themselves have declared war against the Roman people; others are called robbers, or brigands. Therefore, anyone who is captured by robbers, does not become their slave, nor has he any need of the right of postliminium. He, however, who has been taken by the enemy, for instance, by the Germans or Parthians, becomes their slave, and recovers his former condition by the right of postliminium.

Ulpianus, Institutes, Book II. Hence all law consists either in the acquisition, preservation, or diminution of right; for it has reference to the way in which anything becomes the property of a person, or how he can preserve it or his rights, or how he can alienate or lose them.

Ulpianus, Institutes, Book II. The following are the servitudes of rustic estates, namely: the right of walking, driving cattle, the right of way, and the right to conduct water. The first is the right a man has to pass or walk, but not to drive a beast of burden. The second is the right to drive a beast of burden, or a vehicle; and therefore a party who has the right to walk, has not the right to drive cattle; and he who has the latter privilege has also that of walking even without a beast of burden. The third is the right of passing, driving, or walking, for all are included in the right of way. The last is the right to conduct water over the land of another. 1Among rustic servitudes must be enumerated the right to draw water, as well as that to drive cattle to water, the right of pasturage, the rights of burning lime and of digging sand. 2It is clear that the delivery of servitudes and the toleration of the same admit of the intervention of the Prætor.

Ulpianus, Institutes, Book II. We designate buildings urban estates, and where buildings belong to a house in the country, servitudes of urban estates can also be created there. 1These servitudes are said to belong to estates because they cannot be created without them; for no one can acquire a servitude over an urban or rustic estate, unless he himself has an estate.

Ulpianus, Institutes, Book II. Moreover, where a bequest is made as follows: “I wish you to give; I require you to give; I think that you should give,” a trust is created.

Ulpianus, Institutes, Book II. Or where one is exhausted by old age: