The great majority of surviving Aztec religious prayer, including the twenty sacred hymns catalogued individually elsewhere in this atlas and material such as the Prayer to Tezcatlipoca in Time of Plague, comes from the Florentine Codex and the related Primeros Memoriales, an enormous encyclopedic project compiled by the Franciscan friar Bernardino de Sahagun working with Nahua informants and Nahua-trained scribes in the decades following the Spanish conquest, using a methodology remarkably systematic for its time, interviewing indigenous elders and cross-checking their accounts, but still fundamentally shaped by its colonial context and its author's ultimately missionary purpose of understanding Aztec religion partly in order to more effectively work against it. This means that even the most extensive and valuable surviving source for Aztec religious language passed through translation, transcription by scribes trained in a colonial mission school, and the specific interests and limitations of a single Spanish friar's project, a mediated transmission comparable in kind, though not in specific detail, to the Christian-mediated transmission of Norse pagan material discussed elsewhere in this atlas.