The original page 13 of the Codex Borbonicus, showing the 13th trecena of the Aztec sacred calendar. This 13th trecena was under the auspices of the goddess Tlazolteotl, who is shown on the upper left wearing a flayed skin, giving birth to Cinteotl. The 13 day-signs of this trecena, starting with 1 Earthquake, 2 Flint/Knife, 3 Rain, etc., are shown on the bottom row and the right column.
The Codex Borbonicus is one of a very few Aztec codices that survived the colonial Spanish inquisition. When the Spanish conquistadors (led by Hernán Cortés) entered Aztec cities, they would often find libraries filled with thousands of native works. However, most of the works were destroyed during the conquest as a means to hasten the conversion of the Aztec to European ideals.
Amazing! I love how traditional religious art scales figures according to their imporance. It seems counterintuitive to our modern eye that focuses on perspective but there is an undeniable logic to, "most important thing should be largest".