About 1111 CE, a group of clans who would become known as the Aztec or Mexica began their migration from their homeland which they described as an island in a lake named Aztlan. The seven clans were led by their priests on a long migration which would eventually lead to the establishment of the city of Tenochtitlan and an empire which would influence much of what is modern day Mexico.
For the Aztecs, the words of the gods and the procession of time could be read in the skies. They viewed time as cyclical with each unit of time repeating itself. The Aztecs maintained an accurate calendar which enabled them to keep track of the passage of days, months, and years. This knowledge was important in scheduling rituals and in understanding coming events.
For the Aztecs, every person’s destiny was closely tied to the person’s birth date. The cycles of time repeated, so understanding the birth date and the events associated with it provided insights into the individual’s future. If a child were born on a “bad” day, the naming ceremony would be delayed so that the child would have a better future.
The Aztecs had two kinds of time and two kinds of calendars. Sacred time was kept separate from secular time.
The secular calendar was known as Xihuitl (a “stem of grass”, meaning “time of the new grass”). This calendar marked off the changing seasons which are important to planting and harvest. For the people, the secular calendar was used to schedule planting, harvesting, and other routine annual events. In addition, it regulated the market days which were held at five-day intervals.
Numerically, the secular calendar was based on the number 20: cempohualli, meaning “one full count,” that is the total number of fingers and toes on a normal human being. Each month consisted of 20 days and 18 months constituted a year. This meant that the year had 360 days, just a bit shy of the actual 365 of the solar year. The extra five days—known as the nemontemi—were days of evil omen and dread significance as they had no divine patron.
Each month had special religious significance and culminated in a feast where the god of the month was celebrated. Each year began by honoring Tlaloc, the god of rain and ended with a celebration of Xiuhteuctli, the Lord of the Year.
The sacred calendar, known as tonalpohualli, was made up of 260 days: 20 day-signs joined with the numbers 1 through 13. The number 13 represents the 13 layers of the world and the sky. To understand how this works, imagine two lists: one with the names of the days (20) and one with 13 numbers. Combining these we start with 1 Alligator which is followed by 2 Wind, and so on until we reach 13 Reed. Then the numbers start over and the days continue: 1 Jaguar, 2 Eagle, until we reach 7 Flower, which is the end of the twenty days. Then we start the days over and continue with the numbers: 8 Alligator, 9 Wind, and so on. After 260 days, we have linked all of the days with all of the numbers.
Each of the day-names had its own patron god or gods which gave the day special characteristics. The day Rabbit, for example, had as its patron the goddess Mayahuel who was the deity of pulque (a fermented alcoholic drink) and intoxication.
The 260 day sacred year was divided into four 65-day groups of five 13-day weeks. Each of these 65-day groups carried a sign oriented toward one of the four cardinal directions: north, south, east, west. Each of the 13-day weeks also had its own patron god or goddess.
The Aztec sacred calendar bundled the sacred years into four groups of 13 years to form the xiuhmolpilli (“bundle of years”). The priests would mark the passage of each year with a peeled rod. When 52 of these rods had accumulated, they would bind them together and bury them in a ritual which symbolized the start of a new count. The public ceremonies held at this event were filled with apprehension: at this moment, time would expire and it would either be replaced or time would simply end. All fires in the temples, palaces, and households would be extinguished. People would break their idols and possessions and stay awake with the expectation that demons would appear to destroy the world.
On the Hill of the Star, the Fire Priests would watch to see if the Pleiades (a star cluster which is visible to the naked eye in the night sky) would cross the meridian at midnight. If they did, then the universe would continue and a fire would be started in the opened breast of a sacrificed captive. When the priests rekindled the flame symbolizing the start of a new cycle, then the people would know that the world would continue for another 52 years.