As in almost all the early civilizations of which we have record, it is extremely difficult to separate primitive scientific knowledge from its ritual context, but this should not lead one to suppose that a people like the Maya or the Sumerians had not evolved a considerable body of empirically derived information about the natural world. As we shall see, arithmetic and astronomy had reached a level comparable to that achieved by the ancient Babylonians and surpassing in some respects of the Egyptians; but one should not exaggerate.

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Priests and Rites

In contrast to that of the Aztec, the Maya clergy was not celibate. Sons succeeded their fathers to the office, although some were second sons of lords. Their title, Ah Kin ('He of the Sun') suggests a close connection with the calendar and astronomy, and the list of duties outlined by Landa makes it clear that Maya learning as well as ritual was in their hands. Among them were 'computation of the years, months, and days, the festivals and ceremonies, the administration of the sacraments, the fateful days and seasons, their methods of divination and their prophecies, events and the cures for diseases, and their antiquities and how to read and write with the letters and characters . . .', but they also kept the all-important genealogies. During the prosperity of Mayapan a hereditary Chief Priest resided in that city whose main function seems to have been the overseeing of an academy for the training of candidates for the priesthood, but in no source do we find his authority or that of the priests superseding civil power.

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The Sun and the Moon

To the Maya the round of 365 days - eighteen months of twenty days plus the five extra days of the Uayeb - was as close to the solar year as they cared to get. This 'Vague Year' began among the Yucatec of Landa's time on 16 July. Yet the

earth actually takes about 365 J days to complete its journey about the sun, so that the Vague Year must have continually advanced on the solar year, gradually putting the months out of phase with the seasons. We know that none of the Maya intercalated days on leap years or the like, as we do, and it has been shown that more sophisticated corrections thought to have been made by them are a figment of the imagination. Yet their lunar inscriptions show that they must have had an unusually accurate idea of the real length of the tropical year.

Curiously, the Maya went to far greater trouble with the erratic moon (figure 43d). In the inscriptions Initial Series dates are followed by the so-called Lunar Series, which contains up to eight glyphs dealing with the cycles of that body. One of these records whether the current lunar month was of 29 or 30 days, and another tells the age of the moon on that particular Long Count date. Naturally, the Maya, like all civilized peoples were faced with the problem of coordinating their lunar calendar with the solar, but there is slight indication that they used the nineteen-year Metonic cycle (on which the 'Golden Number' in the Book of Common Prayer is based). Instead, from the mid fourth century a.d. each centre made its own correction to correlate the two. However, in A.D. 682 the priests of Copan began calculating with the formula 149 moons = 4,400 days, a system which was eventually adopted by almost all the Maya centres. In our terms, they figured a lunation to average 29.53020 days, remarkably close to the actual value 29.53059.

Of great interest to Mayanists and astronomers alike have been the eclipse tables recorded on seven pages of the Dresden Codex. These cover a cycle of 405 lunations of 11,960 days, which conveniently enough equals forty-six times 260 days; a kind of formula with which the Maya were deeply concerned, for such equations enabled them to coordinate the movements of the heavenly bodies with their most sacred ritual period. The ancients had found out, at least by the mid eighth century a.d. but possibly much earlier, that lunar and solar eclipses (figure 45c) could only occur within plus or minus eighteen days of the node (when the moon's path crosses the apparent path of the sun) ; and this is what the tables are, a statement of when such events were likely. They also seem to have been aware of the recession of the node (or at least of its effect over long periods of time), and Eric Thompson suggests that the astronomer-priests accordingly constructed the tables anew every half-century or so.