158 Reason and Its Rivals (ca. 1550– 1815)the envoy is admitted pursuant to a tacit understanding between the two
states that the immunities will be granted, and natural law requires that this
understanding be duly honored.
Th e result of Suárez’s exposition was to present a dualistic picture of in-
ternational law, reminiscent of that of Isidore but far more detailed. Interna-
tional law, in this view, consists of two conceptually distinct bodies of law.
First is natural law. Th is is not a law applicable to states alone, but to all hu-
mans, from the highest to the lowest. It is applicable to states, though, in the
sense that princes are bound by it in the course of their governmental func-
tions, just as common people are in their day- to- day lives. Th e second com-
ponent of international law is the ius gentium proper. In contrast to natural
law, this is a positive (i.e., man- made) law applicable only to states as such,
arrived at by agreement between the states.
It must be noted that here, too, some watchfulness is required concerning
terminology. In this dualistic outlook of Suárez, there is still no single expres-
sion for “international law” that covers both bodies of law. “Ius gentium” may
translate literally as “law of nations,” but it referred to only one of the two
component types of law, not to both of them in combination. Nevertheless, the
importance of Suárez’s careful exposition of his ius gentium proper, as a corpus
of law applicable solely to interstate relations, can hardly be overstated. It con-
stituted the conceptual core of international law in its modern sense, set out in
clear and explicit form for the fi rst time— and thereby qualifying Suárez as yet
another worthy contender for the elusive title of “father of international law.”Th e Contribution of Hugo Grotius
Th e fi gure who carried Suárez’s conception of the man- made ius gentium to
the wider world was Hugo Grotius. We have encountered him in the ser vice
of the Dutch East India Company, as an opponent of claims to sovereignty
over the high seas. In the ensuing years, his promising career suff ered an
abrupt reversal. He found himself on the losing side in bitter theological
debates, when supporters of more tolerant and moderate forms of Protes-
tantism lost power within the Dutch Republic to partisans of the more rig-
idly Calvinist persuasion. Grotius’s principal po liti cal patron was put to
death, and he into prison. He managed to escape from captivity by the all-
too- appropriate ruse of concealing himself in a crate of books. (A crate on