"The precepts of the law are these: to live honestly, to injure no one, and to give every man his due. 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."
- Justinian (483-565), emperor of Rome, in his Institutes of Roman Law.