The Jesuit letters, particularly those written by the priest Manuel da Nóbrega and collected in Cartas (1549-1558), offer a glimpse of how Brazilian Indians were dealt with through language, liturgy and catechism. This material allows for deep understanding of such topics, specially when compared with those tackled in Diálogo sobre a Conversão do Gentio, which draws on philosophy, theology, literature and the Bible to address major unresolved arguments in the relationship of the settlers and the Jesuits with the Brazilian Indians. Nóbrega wrote it with the purpose of giving voice to the American man, arguing that the natives were human, since they possessed a soul which endowed them with the moral and natural ability to be open to the message of the Gospel and to convert to Christianity as many other peoples before them. In the text, the debate between the two opponents, Matheus Nogueira and Gonçalo Alvares, is superbly rendered, both trying to establish whether it was possible or impossible for the natives to convert. Whereas the Cartas fails to proclaim the opinion of many as opposing, the Diálogo reveals unequivocally the melancholic and pessimistic view of settlers and Jesuits, who believed that it was impossible to convert the Brazilian Indians. However, if we read between the lines we perceive the opposite: namely, that Nóbrega did believe that the natives would eventually accept the Gospel and become Christians.