A major obstacle that Las Casas faced as a polemicist was in rationalizing the Aztec practice of human sacrifice. He confronted this arduous subject through casuistry – through analogous references between Mesoamerican human sacrifice and the Biblical story of Abraham’s impending sacrifice of Isaac. This allusion was in the context of his debate with Sepulveda, who was arguing that the Amerindians were ‘slaves-by-nature’ in accordance with Book 1 of Aristotle’s Politics. Las Casas responded to Sepulveda’s argumentation by describing Aristotle as that ‘pagan philosopher burning in hell’. Quite a remark to make about someone, who was referred to as ‘The Philosopher’ during the Middle Ages, and before university theologians, neo-Thomists, and humanists. His irrepressible indignation was directed even at the king, Philip II, warning him against usurping the authority of the bishop.
But the harsh language of friar Bartolome was not gratuitous and there were kickbacks. A rival friar pointed out that Las Casas exploited three dozen Amerindian porters (tamemes) for carrying his numerous books, and his debating opponent described the apostle of the Indians as being as astute as a fox and as venomous as a scorpion. Satire stings, and indeed, it stings both ways.