Chapter 1 discusses the work of Francisco de Vitoria, one of the fathers of jus gentium, bringing out its full ambivalence: on the one hand Vitoria recognized the rights of New World peoples, including their right of ownership over the lands they inhabited, and he rejected the proposition that it would be justified to wage a “just war” on account of the diversity of customs; on the other hand he wound up ultimately justifying the Spanish conquest by papal mandate in the name of Christian religious propaganda. The complexity of his work can also be appreciated from the analysis through which he compared the Christian world with the Muslim world in the geopolitical space of the Mediterranean. Vitoria conceded the legitimacy of exterminating Muslims, regarded as perpetual hostes of the Christian faith, for the purpose of ensuring “peace” and security. The origins of the clash of civilizations can thus be traced to a much earlier time than that of the reconstruction which Samuel P. Huntington put forward in the 1990s.