Why would you withhold water from my lips?The use of water is a common right.Nor sun nor air nor water's gentle flowAre private things by natural design.The gifts I seek are public property.OvidWhen in 1603 the Dutch East India Company seized a Portuguese carack as a prize, this was not in itself a notable episode in the annals of colonial history. With the growing efforts of the Dutch to challenge the monopoly of the Portuguese in the use of the sea route to the East Indies, such incidents were beginning to become commonplace. What marked out this particular incident, however, was the fact that it prompted the publication, in 1609, of an anonymous treatise under the suggestive title of Mare Liberum.1 The author behind the work was Hugo Grotius, by that time an enthusiastic supporter of the idea of an aristocratic and imperialist Dutch republic.2In the Iberian Peninsula, which had been targeted by the corrosive arguments put forth in Mare Liberum, the Spanish Inquisition included the book in its index of forbidden works in 1612. Thirteen years later, however, a book entitled De iusto imperio Lusitanorum Asiatico was published in reply to the Incognito's attack by Serafim de Freitas, a Portuguese friar teaching at the Faculty of Law of Valladolid. This late publication in 1625 of a response to Grotius is explained by Philip III's engagement in a policy of peace and good relations with the United Provinces. Eleven more years elapsed before John Selden's long-awaited treatise in defense of exclusive fishing rights in English waters appeared.Selden's Mare Clausum (1636), for many a deeply Grotian work,3 has been, among all the replies to Grotius, the one which has exercised the greatest hold over scholars. By contrast Freitas has hardly been noticed at all in the Anglophone literature.4 But nothing seems to justify this omission. Freitas's treatise is an earlier, fuller, more systematic and perhaps historically more significant discussion of Grotius's Mare Liberum. The purpose of this article is to add this missing dimension of the debate, while pointing out that Freitas anticipated many of the terms of the discussion later picked up by Selden. It is likely that Selden never had access to Freitas's treatise. Therefore, in this article, I am not advancing any claim to a direct influence of Freitas's treatise on dominion over the high seas upon Selden's work, which, despite the argumentative similarities, concentrates on the question of fishing rights in the North Sea. As Grotius never responded to either author, the time has come to overcome this silence by bringing together Grotius's and Freitas's arguments, as well as indicating some of the more significant late Scholastic and juristic sources to which they are indebted. Though Grotius did not reply to Freitas, there is evidence that he came to know about the latter's work, for as early as April 1617, in a letter addressed to his brother, Grotius states that someone had written in Salamanca a refutation of his Mare Liberum. Despite the misleading reference to Salamanca, this reply could well be Freitas's, as, in February 1627, Grotius writes yet another letter stating that he had read Freitas's De iusto imperio.5Among these sources, two works, Francisco de Vitoria's famous lectures on the Indies (1539) and Ferdinande Vazquez y Menchaca's Controversiarum illiustrium usuque frequentium libri tres (1564) are of particular significance. Plain numbers would serve to substantiate this claim, as in Grotius's De iure praedae 68 references are made to Vitoria and 74 to Vazquez, whose names are also recurrent in Freitas's De iusto imperio. As to Selden, who opposes Vitoria in Mare Clausum, and devotes the whole of its chapter xxvi, book I, to the direct refutation of Grotius's and Vazquez's theses, he had most probably contact with Vazquez's ideas through Johannes Gryphiander's treatise De insulis tractatus (1624). Although both Grotius and Freitas draw heavily on Vitoria's discussion of the just and unjust titles by which jurisdiction (dominium iurisdictionis) or even property rights (dominium rerum) could be gained over the Americas, they disagree as to the cogency of many of Vitoria's arguments. …