Calendar Round Almanacs in the Codex Borgia

Chapter 4 analyzes the chronology of Calendar Round dates in the Codex Borgia to show a relationship with seasonal cycles and specific astronomical events. The first section analyzes the rain almanacs on Borgia 27–28 and their relationship to Venus cycles, weather patterns, and long-term climate records known from the study of tree-ring records in Central Mexico. This chapter also explores Calendar Round dates and related directional symbolism on Codex Borgia pages 49–52, an almanac that represents year-end rituals associated with the four cardinal directions. Another almanac on these same pages focuses on deities representing the skybearers who hold up the sky and their association with four yearbearer glyphs that name the years.