In the first book the author endeavours to prove that the sea is not everywhere common, but is capable of appropriation, and has been in fact in numerous cases appropriated. The objections to that opinion are classified in three groups: first, that it is contrary to the law of nature and the law of nations to forbid free commerce and navigation; second, that the physical nature of the sea, its fluidity and fluxion, renders it incapable of occupation; third, the opinions of certain learned men. He argued that the ancient law as to the community of things had become modified in certain particulars, and that the received practice and custom of many nations, ancient and modern, showed that the sea was capable of private dominion, and that such dominion or appropriation was therefore not contrary either to the law of nature or the law of nations. In support of his argument Selden drew freely upon the vast stores of his erudition. He began, like Welwood, by quoting Scriptures to show that the divine law (_jus divinum_) allowed private dominion in the sea, and that according to the opinion of those learned in the Jewish law, a great part of the sea washing the west coast of the Holy Land had been annexed to the land of Israel by the appointment of God. Among almost all the nations of antiquity, he said, it was the custom to admit private dominion in the sea, and many of them exercised maritime sovereignty.[666] Among modern nations, sovereignty was exercised by the Venetians in the Adriatic, by the Genoese in the Ligurian Sea, by the Tuscans and Pisans in the Tyrrhenian Sea, and by the Pope over a part of the sea called _Mare Ecclesiæ_. Then the sovereignty claimed by the Spaniards and Portuguese, and the maritime dominion of the Danes and Norwegians, were notorious. Even the Poles and the Turks possessed sovereignty in the Baltic and the Black Sea respectively. How then could it be denied, with all these examples, ancient and modern, that the sea could not be appropriated? Selden indeed agreed with Grotius in repudiating the sovereignty claimed by Spain and Portugal in the great oceans,--not, however, because it was opposed to reason and nature, but because it was founded on no legitimate title, and these nations had not a sufficient naval force to assert and maintain it.[667]