The Eighteen Feasts of the Mexica Year takes as its first authority the corpus of texts written by the Mexica (or Aztecs) themselves, in the script which in their language (Nahuatl) is known by the term tlacuilolli. Texts in this script are preferred to alphabetic transcriptions and other derivative sources, in the attempt to establish the paradigms of the Mexica calendar year.
These are shown coherently to govern the regulation of such social practices as tribute, agriculture and ritual performance, as well as to impinge on more philosophical concerns with the articulation of time as such, especially in the interface with imported western conventions and the Christian ecclesiastical year.