 As mentioned above, in the first of his three lectures De Indis, delivered in the summer of 1539, he shows that the Amerindians were veri domini of their goods, even if they were unbelievers, sinners, and irrational (Vitoria 1991b: 239–250). He discussed the argument from Aristotle that “barbarians” were little better than animals, madmen or those lacking sense, then he turned to an argument of apologists for the Conquista, claiming that Amerindians were infidels, living in a perpetual state of mortal sin, requiring Christian intervention. He dismissed the argument from sin, on the grounds that sin did not cancel natural dominium. Brute beasts lacked such rights, but even children and the mad, although they had guardians, nevertheless had property rights. Aristotle wrote about those who needed direction from others, but this did not negate ownership. Vitoria extended rightful ownership even to Saracens. He blamed the poor education of indigenous peoples, which he compared to that of many European peasants, for their depraved condition. Slavery, he added, was a legal or civil construct. No one was a slave by nature.