Most of the codex consists of almanacs: the 260-day count laid out in rows, divided and subdivided, each interval attached to a deity, an offering, an omen and a task. They cover planting and rain, beekeeping, deer hunting, weaving, disease and its cures, and the ceremonies of the year-bearers. This is the working material of a Maya priest, closer to a manual than to a narrative, and it is written in the hieroglyphic script with numbers alongside.
Set among it are the astronomical tables that made the book famous. The Venus table tracks the synodic cycle of the planet, its appearances as morning star and evening star and its two disappearances, using a canonical figure of 584 days against a true value of about 583.92, and supplies correction intervals to be applied periodically so that the table does not drift out of true across centuries of use. That correction is the impressive part: the Maya astronomers knew their round number was slightly wrong and built the compensation into the instrument. The eclipse table sets out 405 lunar months in groups of five and six, marking the stations at which a solar eclipse becomes possible. It does not predict which eclipses will be visible from Yucatan and was not designed to. Multiplication tables of the kind needed to run these cycles against each other and against the 365-day year sit alongside them.
The final page shows a flood: water pouring from the body of a sky serpent and from a celestial band above, an aged goddess emptying a jar, and a dark deity below carrying weapons. It is a scene of destruction by water, of a kind attested elsewhere in Maya and central Mexican thought, and it has since been made to carry a great deal more weight than it will bear.