Yucatan Before and After the Conquest, by Diego de Landa, tr. William Gates, , at sacred-texts.com
The sun does not sink or go away far enough in this land of Yucatan for the nights to become longer than the days; thus in their full maximum, from San Andrés to Santa Lucia [Nov. 30 to Dec. 13] they are equal, and then they begin to lengthen. To know the hour of the night the natives governed themselves by the planet Venus, the Pleiades and the Twins. During the day they had terms for midday, and for different sections from sunrise to sunset, according to which they recognized and regulated their hours for work.
They had their perfect year like ours, of 365 days and 6 hours, which they divided into months in two ways. In the first the months were of 30 days and were called U, which signifies the moon, and they counted from the rising of the new moon until it disappeared.
In the other method the months had 20 days, and were called uinal hunekeh; of these it took eighteen to complete the year, plus five days and six hours. Out of these six hours they made a day every four years, so that they had a 366-day year every fourth time. *
For these 360 days they had 20 letters or characters by which to designate them, without assigning names to the five supplementary days, as being
sinister and unlucky. The letters are as follows, each with its name above to understand their correlation with ours.
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I have already related that the Indian method of counting was from five to five, and four fives making 20; thus then from these 20 characters they take the first of each set of five, so that each of these serves for a year as do our Dominical letters, being the initials days of the various 20-day months (or uinals). Thus:
Among the multitude of gods worshipped by these people were four whom they called by the name Bacab. These were, they say, four brothers placed by God when he created the world, at its four corners to sustain the heavens lest they fall. They also say that these Bacabs escaped when the world was destroyed by the deluge. To each of these they give other names, and they mark the four points of the world where God placed them holding up the sky, and also assigned one of the four Dominical letters to each, and to the
place he occupies; also they signalize the misfortunes or blessings which are to happen in the year belonging to each of these, and the accompanying letters.
The evil one, who has in this as in many other cases deceived them, fixed for them the services and offerings hat had to be made in order to evade these misfortunes. Thus if they failed to occur, they said it was because of the ceremonies performed; but if they did come to pass, the priests made the people believe that it was because of some error or fault in the ceremonies,
In whatever ceremony or solemnity these people celebrated for their gods, they always began by driving away the evil spirit, in order the better to perform it. This exorcism was at times by prayers and benedictions they had for this purpose, and at other times by services, offerings and sacrifices which they performed for that end. In order to celebrate the solemnity of the New Year with the greatest rejoicing and dignity, these people, with their false ideas, made use of the five supplementary days, which they regarded as 'unlucky,' and which preceded the first day of their new year, in order to put on a great fiesta for the above Bacabs and the evil one, to whom they gave four other names, as they had done to the Bacabs; these names were: Kan-uvayeyab, Chac-uvayeyab, Sac-uvayeyab, Ek-uvayeyab. * These ceremonies and fetes being over, and the evil one driven away, as we shall see, they began their new year.
59:* We now know that the Mayas knew the exact length of the true solar year as 365.2420 days, that is with a minus error of 0.0002, while our present Gregorian calendar has it as 365.2425, or a plus error of 0.0003. Also that they knew and recorded it on their monuments more than a thousand years before the Spaniards came, and while Europe still had the yet more incorrect method used in Landa's time, of an even day added each four years.
Every kind of guess has been made as to how the Aztecs and Mayas handled the leap-year correction, until very recent researches have proved beyond doubt that the Mayas, at least, solved it by first establishing a purely mathematical 'time unit' of 360 days, without fractions, and then adjusted not only the various lunar and planetary risings and periods, but also the solar year itself, with its seasons.
We also know that they knew the moon's period accurately, as 29.5209 days, but we find no evidence on the monuments or in the Maya records of any use of a 30-day month, in the ordinary sense.
59: This is incorrect; the five last days of the year bore their names regularly, as shown elsewhere by Landa himself in describing the common 52-year cycle used for mundane matters p. 60 by both Mayas and Aztecs, or 52 × 365 days, the 2nd, 3rd and 4th years of each 4-year 'lustrum' beginning with the 6th, 11th and 16th in order of the twenty. Had the last 'five days been actually nameless, every year would have begun on the same day of the twenty. This also would have thrown their Long Count, or chronological order of days, completely out of order.
Throughout the following pages we have substituted the standard type forms of the characters for the days and months or uinals, for the shapes found in the Landa manuscript, there being no question of their identity. See the present writer's Outline Dictionary of Maya Glyphs.
61:* In the above names the words chac, sac, ek, kan mean respectively red, white, black and Yellow, the four colors assigned in this order to the East, North, West and South. It is delightful to note Landa's naive persistence that they always exorcised the evil one in order to worship him. Uvayeyab simply means 'the couch of the year.'