Unfortunately, only four Maya codices survived the Spanish invasion and these are mainly ritualistic-calendrical in content rather than historical. These documents, written in an early form of Yucatecan Maya, are in the format of a screen fold that resembles a European style book. The scholarly controversy over one of these codices, the Grolier Codex, illustrates some of the pitfalls encountered in trying to reconstruct Mayan modes of thought from the evidence available.