1Ulpianus, 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:

2Pomponius, Enchiridion, For instance, reverence towards God, and the obedience we owe to parents and country:

3Florentinus, Institutes, Book I, As we resist violence and injury. For, indeed, it happens under this law what whatever anyone does for the protection of his body is considered to have been done legally; and as Nature has established a certain relationship among us, it follows that it is abominable for one man to lie in ambush for another.

4Ulpianus, 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.

5Hermogenianus, Epitomes of Law, Book I. By this Law of Nations wars were introduced; races were distinguished; kingdoms founded; rights of property ascertained; boundaries of land established; buildings constructed; commerce, purchases, sales, leases, rents, obligations created, such being excepted as were introduced by the Civil Law.

6Ulpianus, 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.

7Papinianus, Definitions, Book II. The Civil Law is that which is derived from statutory enactments, plebiscites, decrees of the Senate, edicts of the Emperors, and the authority of learned men. 1The Prætorian Law is that which the Prætors introduced for the purpose of aiding, supplementing, or amending, the Civil Law, for the public welfare; which is also designated honorary law, being so called after the “honor” of the Prætors.

8Marcianus, Institutes, Book I. For honorary law itself is the living voice of the Civil Law.

9Gaius, 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.

10Ulpianus, Rules, Book I. Justice is the constant and perpetual desire to give to every one that to which he is entitled. 1The precepts of the law are the following: to live honorably, to injure no one, to give to every one his due. 2The science of the law is the acquaintance with Divine and human affairs, the knowledge of what is just and what is unjust.

11Paulus, On Sabinus, Book XIV. The term “law” is used in several ways. First, whatever is just and good is called law, as is the case with natural law. Second, where anything is useful to all or to the majority in any state, as for instance the Civil Law. Nor is honorary law less justly so designated in Our State, and the Prætor also is said to administer the law even when he decides unjustly; for the term has reference not to what the Prætor actually does, but to that which it is suitable for him to do. Under another signification, the word indicates the place where justice is administered, the name being shifted from the act itself to the locality where it is performed, and this locality may be determined in the following manner; whenever the Prætor may designate a place for the dispensation of justice, that place is properly called the law, provided the dignity of his office and the customs of our ancestors are preserved.

12Marcianus, Institutes, Book I. Sometimes the term “law” is used to denote a connection, as for instance, “I am connected by the law of consanguinity or affinity with such-and-such a person”.