New Worlds and Th eir Challenges 133ography as well as law. His experience in international aff airs began early. In
1598, before he was twenty, he accompanied a Dutch diplomatic mission to
Paris. Later, he undertook legal work for the Dutch East India Company, in
the course of which he wrote (but did not publish) a lengthy treatise to jus-
tify the captures of Portuguese vessels in the Indian Ocean by ships of the
Dutch East India Company. He called this work De Indis (On the Indies),
although, when it was fi nally published in full in the nineteenth century, it
was given the title De jure praedae (On the Law of Prize), under which it is
now commonly known. In all events, Grotius assured the Dutch captors
that they should not hesitate to assert their rights “through an anxious and
overnice avoidance of things not essentially dishonourable.”
Grotius brought a battery of legal arguments to bear against the Portu-
guese and in favor of the East India Company. Central to his case was the
proposition that the high seas, by their nature, are not susceptible of own-
ership as private property. On this thesis, the papal grants could be sum-
marily dismissed as “a vain and empty pretext.” He also devoted consider-
able attention to refuting claims that prescription might be the basis of
Portugal’s rights. He was careful, too, to build a case for the waging of just
war by the Dutch East India Company in its own right, without regard to
whether the Dutch state was itself at war with Portugal.
In his opposition to own ership of, or sovereignty over, the high seas, Gro-
tius built on earlier work by others, specifi cally on objections that Spain had
made to Venice’s claim to own ership of the Adriatic Sea. In 1564, an attack
on these claims was made by a Spanish writer named Ferdinando Vázquez y
Menchaca. Vázquez was a native of Valladolid, the son of a member of the
royal council of Castile. He studied under Vitoria at the University of Sala-
manca and went on to become a legal adviser to King Philip II of Spain, and
also to teach at Salamanca and to write on questions of natural law. In a book
devoted largely to various issues of private law, he articulated Spain’s objec-
tions to Venice’s claim of sovereignty over the Adriatic. His argument—
adopted later by Grotius— was to the eff ect that the only possible basis of title
could be occupation— and that occupation of whole seas was impossible be-
cause it required a continuous presence and an eff ective exercise of govern-
mental power.
In the longer term, Grotius’s labors became better known than those of
Vázquez because they were published separately (and anonymously) in