The Sacred Round

by John P. Pratt
(updated 2 June 2009)


The 260-day Sacred Round (also called the tzolkin) is the heart of the Aztec Calendar, the Mayan calendar and nearly every native calendar of Central America. The sacred round is composed of two cycles, one of 20 named days, and one of 13 numbered days, each of which continuously repeats. It takes 260 days for the two cycles to realign on the beginning day of each cycle (260 = 20 x13), so the Sacred Round has 260 days.

I will use the term "Mayan Calendar" to refer to a composite generic version of the calendar of Central America. The same basic calendar was used with minor variations by the Mayans, Aztecs, Toltecs, Mixtecs, and hundreds of other tribes throughout North and South American for untold generations. There is, however, surprisingly little difference between most versions, considering that it has been used for about 3,000 years.

The 20-day Vientena

Day Glyphs from Aztec Calendar
The 20 day glyphs from the Aztec Calendar stone.
The fundamental cycle is the 20-day count, called the vientena. Each of the days was named and had an associated picture or glyph. The 20 day glyphs are shown in a circle in the famous Aztec Calendar Stone. This illustration is only of the central part of that calendar. The 20-day cycle begins at the top and goes around counter-clockwise.

The names were taken as the best English words to describe the name. Every tribe had a slight variation of the pictures and of what the name should be. For example, the first figure was either a crocodile, a water lily, or the sun. In every case, according to the Mayan priests, the original idea was that of the conception of new life. The crocodile and water lily, both floating in the water, fit the image of a fetus in the womb. The Olmec figure of the sun may represent the moment when the spark of life begins. I chose the word "Light" to best summarize this idea.

The days were said by the Mayans to represent the steps in a person's life (from before birth to after resurrection). Thus, after the first day (conception), the second (Wind) is when the spirit enters the baby, and the third (temple) is when the day of birth. The names and symbolism are explain in more detail on a separate page.

Note that the circular arrangement is important because there are several pairs of opposites. For example, the fifth day in the cycle is "Serpent," and directly opposite the serpent is the "Eagle." The eagle/serpent pair was so important to the Aztecs that their capital (now Mexico City) was founded where they saw the eagle with the serpent in its talons (now immortalized on the Mexican flag.)

Some days may represent the day on which a sacred ordinance is performed. For example the day Jaguar represents being "washed clean" and several tribes had baptism ceremonies. Again, note that opposites are across from each other in the circle of days: Jaguar (Baptism) is opposite Lizard, the day when evil enters a child's life. The symbolic meanings of each glyph is worth knowing, so I explain them in as much detail as I can.

The vientena is also the fundamental cycle of the Mayan Long Count, which is not discussed here. Moreover, Native American astrology, and assigning of similar traits to people is based on which day of the vientena they are born on. This is described in a book entitled The Cherokee Sacred Calendar, by Raven Hail.

The 13-day Trecena

Sacred Round or Tzolkin
The Sacred Round is like two connected gears. The date indicated is 1 Light, the first day of the Sacred Round. The next day will be 2 Wind.
The 13-day cycle, called the trecena, simply numers the days rather than using pictures. The two cycles continue separately from each other. That is, one numbers the days from 1 to 13 and then begins again with 1. It is very similar to how there are seven days in a week, and they just keep repeating. No extra days are ever inserting into the week, and none are ever inserted into either the trecena or the vientena.

The two cycles each separately move through one day at a time, so the effect is similar to two gears, one with 13 cogs and the other with 20, as shown in the illustration. The figures there are taken from the Mixtec (Codex Nuttall), which are only slightly different from the Aztec. Thus, the Sacred Round begins at the position shown on the day 1 Light. The next day is 2 Wind and then 3 Temple. That may sound confusing if were expecting 1 Light to be followed by 2 Light and then 3 Light. But we do the same thing on our modern Gregorian calendar. The day after Monday the 1st is Tuesday the 2nd. That is because the week of seven days progresses daily even as do the days of the month. The thirteenth day of the cycle is 13 Reed. The following day is 1 Jaguar, because the trecena starts over, but the vientena continues on through all 20 figures. It takes 260 days to get back to the starting position (13 x 20 = 260), so the Sacred Round contains 260 days.

One can ask whether the Sacred Round consists of 13 cycles of 20 days or 20 cycles of 13 days. Almost every author I have read gets this backwards. The Native American think of the Sacred Round as 20 trecenas. Each is named for its first day. Thus the first trecena is 1 Light. The second is 1 Jaguar. The entire Sacred Round is listed on a separate page.

The only reason modern authors usually list the Sacred Round as 13 groups of 20 is that it is much easier to make a table of 260 numbers rather than 260 words. But it is important to get it right if one actually wants to use it.