This study addresses the relation between the life and writings of Garcilaso Inca de la Vega through an archival reconstruction of his post as sacristan at the Cathedral of Córdoba and its reflection in his books. It shows that he was incorporated into the jurisdiction of Córdoba's Cathedral Chapter, but that he was not immediately granted full possession of his office. Confronted with ecclesiastical requirements for promotion to such a post, he carefully selected key autobiographical episodes to portray himself as well suited for promotion and responded to the mandatory purity-of-blood examination by displaying his genealogy and by construing a version of Inca history as a development of teachings and institutions that created a pure, immemorial Christianity, despite its recent arrival in the Andes. Garcilaso, though, hid these aspirations from the reader's view. This study brings to the forefront his covert engagement with the challenges of his ecclesiastical career.