64 Law and Morality Abroad (to ca. ad 1550)Arian variant of Christianity to the Catholic one. Th e universal reach of his
knowledge (by the somewhat modest standard of his time) was so impres-
sive that it later (much later) led to his being suggested as an appropriate
patron saint of the internet in the twenty- fi rst century.
According to Isidore, natural law and the ius gentium resembled one an-
other in both being universal but in diff erent respects. Natural law was re-
garded as being, by its very nature, inherently universal. It was applicable
everywhere by virtue of its intrinsic perfection. Broadly in line with the or-
ganic outlook of the stoics, Isidore held natural law to be universal by
necessity— that is, “by the instinct of nature” and not by “any regulation.”
Th is was broadly the opinion of Ulpian. Th e ius gentium, in contrast, was
universal in a diff erent and lesser fashion— in what might be called an em-
pirical or statistical sense. Th at is to say, it was universal by virtue of the fact
that, de facto, “nearly all nations (gentes) use it.” What this conception
clearly implied— but which Isidore did not explicitly expand upon— was that
the ius gentium was a purely human creation. As such, it should be seen as a
product of human free will.
In addition, the two bodies of law applied to diff erent subject areas.
Isidore helpfully provided some illustrations. Principles and practices aris-
ing out of natural law included the union of men and women in marriage;
children’s inheritance and education; the right of all persons to acquire any-
thing from “the sky, the earth, and the sea”; the duty of persons to return
things entrusted to them; and the right of self- defense (i.e., to use force to
repel violence). Th ings falling into the category of ius gentium included wars
(including the right to capture and enslave enemy troops), the right to oc-
cupy vacant territory, truces and peace treaties, the inviolability of foreign
envoys, and prohibitions of marriages between diff erent races. Th e simi-
larity to the position of Hermogenian in the Roman-law Digest is clearly
apparent.
It will be observed that there is a basic diff erence between these two lists
of topics. Th ings covered by natural law pertain largely to the conduct of
individual persons, such as marriage, the bringing up of families, and the
fending off of assaults. Th ings falling into the ambit of the ius gentium, in
contrast, are activities of states, including various aspects of war making
and peacemaking. Isidore therefore went a very long distance toward giving,
as the realm of the ius gentium, topics that would later be taken, as a matter