s of mankind.

The Romans described their legal system as consisting of two
ingredients. "All nations," says the Institutional Treatise published
under the authority of the Emperor Justinian, "who are ruled by laws
and customs, are governed partly by their own particular laws, and
partly by those laws which are common to all mankind. The law which a
people enacts is called the Civil Law of that people, but that which
natural reason appoints for all mankind is called the Law of Nations,
because all nations use it." The part of the law "which natural reason
appoints for all mankind" was the element which the Edict of the
Praetor was supposed to have worked into Roman jurisprudence. Elsewhere
it is styled more simply Jus Naturale, or the Law of Nature; and its
ordinances are said to be dictated by Natural Equity (_naturalis
aequitas_) as well as by natural reason. I shall attempt to discover
the origin of these famous phrases, Law of Nations, Law of Nature,
Equity, and to determine how the conceptions which they indicate are
related to one another.

The most superficial student of Roman history must be struck by the
extraordinary degree in which the fortunes of the republic were
affected by the presence of foreigners, under different names, on her
soil. The causes of this immigration are discernible enough at a later
period, for we can readily understand why men of all races should
flock to the mistress of the world; but the same phenomenon of a large
population of foreigners and denizens meets us in the very earliest
records of the Roman State. No doubt, the instability of society in
ancient Italy, composed as it was in great measure of robber tribes,
gave men considerable inducement to locate themselves in the territory
of any community strong enough to protect itself and them from
external attack, even though protection should be purchased at the
cost of heavy taxation, political disfranchisement, and much social
humiliation. It is probable, however, that this explanation is
imperfect, and that it could only be completed by taking into account
those active commercial relations which, though they are little
reflected in the military traditions of the republic, Rome appears
certainly to have had with Carthage and with the interior of Italy in
pre-historic times. Whatever were the circumstances to which it was
attributable, the foreign element in the commonwealth determined the
whole course of its history, which, at all