It's a book. Paper bark or parchment. . The Aztecs didn't have full writing in the sense of a system to represent a spoken language. Aztec codices are more to

It's a book. Paper bark or parchment. . The Aztecs didn't have full writing in the sense of a system to represent a spoken language. Aztec codices are more to the calendar and graphic end of things. (But I could be wrong, since so few examples, are truly from pre-exchange times.) The primacy of stone is a misconception. The following applies not just to the Aztecs, but also Sumer and Babylon, Egypt, the Maya, etc: the primary writing material for all of these civilizations was not stone. It was perishable materials, including parchment, wood bark, wax tablets, papyrus in Egypt, or just drawing in a pile of fine sand to do some arithmetic. (Babylon and its fired clay is a bit of an exception, maybe. But they also wrote on wood, bark paper and cloth, among other things.) That means we only get monumental inscriptions. I'm more familiar with the Maya, who did have a complete writing system for spoken language, and we strongly suspect the Maya had literature in the same way the Egyptians, Chinese or Sumerians did. Poetry anthologies, mythological anthologies, religious texts, and also textbooks on medicine and astronomy, etc. Obviously, they didn't carve those on monuments, they wrote them on the closest analogue to paper they had. Unfortunately, neither Mexico's meteorological climate nor Spain's religious climate at the time was conducive to preserving such fragile books.