According to tradition Rome was founded in 753 B. C. In the twenty-seven centuries since then Roman law has lived two lives and makes two claims on our attention. In its first life it was the law of the city of Rome and, in its ultimate maturity, of the whole Roman Empire. But it was more than this. It was the most original product of the Roman mind. In almost all their other intellectual endeavors the Romans were the eager pupils of the Greeks, but in law they were, and knew themselves to be, the masters.
In their hands law became for the first time a thoroughly scientific subject, an elaborately articulated system of principles abstracted from the detailed rules which constitute the raw material of law. This process of abstraction is important not merely for the simplicity of formulation which it makes possible, but also because principles, unlike rules, are fertile: a lawyer can by combining two or more principles create new principles and therefore new rules. The difference between a system of principles and a system of rules may thus be likened to the difference between an alphabetic script and a system of ideographs such as the Chinese.
It was the strength of the Roman lawyers that they not only had the ability to construct and manipulate these abstractions on a scale and with a complexity previously unknown, but had also a clear sense of the needs of social and commercial life, an eye for the simplest method of achieving a desired practical result, and a readiness to reject the logic of their own constructions when it conflicted with the demands of convenience. If the law is ‘practical reason’ it is not surprising that the Romans, with their genius for the practical, should have found in it a field of intellectual activity to which they were ideally suited.
This first life of Roman law was summed up, and in the event brought to a close, by the Emperor Justinian in the sixth century A. D. It claims our attention for the intrinsic quality of its intellectual achievement. But five and a half centuries later the law books of Justinian came to be studied in northern Italy, and there began, at first in the universities and later in the courts, the astonishing second life of Roman law which gave to almost the whole of Europe a common stock of legal ideas, a common grammar of legal thought, and, to a varying but considerable extent, a common mass of legal rules.
(Jolowicz, 1972) England stood out against this Reception of Roman law and retained its own Common law largely but not entirely uninfluenced by the Roman. Hence it is that in the world today there are two great families of law of European origin—the one deriving from the Common law of England and embracing the greater part of the English-speaking world, and the other rooted, or partly rooted, in the revived Roman law and including almost all the countries of Europe and a number of others besides.
In contrast to the Common law these Romanistic systems are commonly called Civil law, the name by which until quite recently the Roman law itself was known. The Roman law thus makes this second claim on our attention, that it provides the Common lawyer with a key to the common language of almost every other system of law which traces its origin to Europe. It is not for the whole of Roman law, however, that this claim can be substantiated. The Romans themselves made a distinction between public law and private law.