With the Nemontemi, the count of the xiwitl comes to an end. The Mexika marked the final day of Nemontemi by the observed equinox sunrise as measured by the Templo Mayor. This astronomical event signaled the “bundling” of a unit of time, and the end of the year. We celebrate this “tying off” of the year instead of the upcoming “new year” – a subtle shift in thinking that forces us to recognize that our ancestors marked the end of cycles, rather than their beginnings. Therefore, we can say “In Xiwitl Intlamiliz” or “the year has ended” instead of “Happy New Year.” Every four years, the final day of Nemontemi is “duplicated” or stretched across two days, to account for the extra day it takes the sun to return to its original starting position on the horizon on the Spring Equinox. This allows the Tonalpowalli to continue uninterrupted.
From the Florentine Codex (Book 2, Page 35):
“The five remaining days of the year they named Nemontemi, which means barren days. And they regarded them as unlucky and of evil fortune. There is conjecture that when they pierced the boys’ and girls’ ears, which was every four years, they set aside six days of Nemontemi, and it is the same as the bissextile which we observe every four years.
These five days they held as of evil fortune and unlucky. They said that those who were born in them had evil outcomes in all their affairs and were poor and wretched. They named them Nemo. If they were men, they named them Nemokich; if it was a woman, they named her Nenziwatl. They dared do nothing in these days because they were unlucky. Especially did they abstain from quarreling, because they said that those who quarreled in these days al-ways remained with that custom. They held as a bad omen stumbling in these days.”
Modern Interpretations of Nemontemi (adapted with permission from the work of micorazonmexica):
These extra five days exist between the end of one xiwitl and the beginning of another, and therefore fall outside of the 20-count ordering of time and introduce chaos and disorder to what is otherwise a perfectly ordered system. For these reasons, Nemontemi are considered the worst days of the year, on which all kinds of terrible things are likely to happen. During Nemontemi, couples should refrain from having sex for fear of getting pregnant or introducing chaos into their relationships. New projects should not be started, and new journeys should not be undertaken. It is said that if you trip and fall, you will never be able to rise and you will find that all your undertakings will fail throughout the year. Light no kopal and make no offerings, for the Teteoh will not look kindly upon you. Kwawtemok, the last emperor of the Mexika, was crowned during Nemontemi during the height of the war against the Spanish, and for this reason, lost his kingdom. On these days try to avoid mishaps, start nothing new, and anticipate with joy the beginning of a new cycle which will begin once the last day of Nemontemi has ended.
The Mexika Calendar System 