2 Having laid down these general definitions, and our object being the exposition of the law of the Roman people, we think that the most advantageous plan will be to commence with an easy and simple path, and then to proceed to details with a most careful and scrupulous exactness of interpretation. Otherwise, if we begin by burdening the student's memory, as yet weak and untrained, with a multitude and variety of matters, one of two things will happen: either we shall cause him wholly to desert the study of law, or else we shall bring him at last, after great labour, and often, too, distrustful of his own powers (the commonest cause, among the young, of ill-success), to a point which he might have reached earlier, without such labour and confident in himself, had he been led along a smoother path. 3 The precepts of the law are these: to live honestly, to injure no one, and to give every man his due. 4 The study of law consists of two branches, law public, and law private. The former relates to the welfare of the Roman State; the latter to the advantage of the individual citizen. Of private law then we may say that it is of threefold origin, being collected from the precepts of nature, from those of the law of nations, or from those of the civil law of Rome. TITLE II. OF THE LAW OF NATURE, THE LAW OF NATIONS, AND THE CIVIL LAW 1 The law of nature is that which she has taught all animals; a law not peculiar to the human race, but shared by all living creatures, whether denizens of the air, the dry land, or the sea. Hence comes the union of male and female, which we call marriage; hence the procreation and rearing of children, for this is a law by the knowledge of which we see even the lower animals are distinguished. The civil law of Rome, and the law of all nations, differ from each other thus. The laws of every people governed by statutes and customs are partly peculiar to itself, partly common to all mankind. Those rules which a state enacts for its own members are peculiar to itself, and are called civil law: those rules prescribed by natural reason for all men are observed by all peoples alike, and are called the law of nations. Thus the laws of the Roman people are partly peculiar to itself, partly common to all nations; a distinction of which we shall take notice as occasion offers.