In Calculating Brilliance, I follow up on arguments that there is a relationship between the Central Mexican deity Quetzalcoatl, the Mayan K’uk’ulkan and the treatment of Venus in the Dresden Codex — but, as Forstemann and Seler deduced over a century ago, the references are implicit. In this presentation, I offer a new interpretation of the Borgia Codex pages 29 through 54 and how they speak to a complex interweaving of astronomy and politics during the Terminal Classic and Postclassic periods across Mesoamerica.