 The second lecture lists seven “unjust titles” for the war against the Amerindians. Vitoria rejected the idea that either the emperor or the pope is master of the world. He denied that Emperor Charles V could take away the domains of others. He cited Juan de Torquemada’s Summa de ecclesia to prove that the pope’s supremacy was spiritual, not temporal; and he maintained that the pope could not force unbelievers to convert. According to Vitoria, discovery was not a justification for conquest; and he refuted the view that sins against nature like cannibalism and incest, which were exceptions to the natural immunity that canon law allowed to non-believers, justified conquest. There were sinners in every nation, but the pope was not entitled to wage war against Christians who were guilty of sin. Furthermore, neither the alleged voluntary choice of the Amerindians nor the idea of a gift from God could justify the conquest of their territory (Vitoria 1991b: 252–276).