The Spirit of the dead Aztec is attacked by an Evil Spirit who scatters Clouds of Ashes
Gilbert James
The Calendar System
As has been said, the calendar system was the source of all Mexican science, and regulated the recurrence of all religious rites and festivals. In fact, the entire mechanism of Nahua life was resident in its provisions. The type of time-division and computation exemplified in the Nahua calendar was also found among the Maya peoples of Yucatan and Guatemala and the Zapotec people of the boundary between the Nahua and Maya races. By which of these races it was first employed is unknown. But the Zapotec calendar exhibits signs of both Nahua and Maya influence, and from this it has been inferred that the calendar systems of these races have been evolved from it. It might with equal probability be argued that both Nahua and Maya art were offshoots of Zapotec art, because the characteristics of both are discovered in it, whereas the circumstance merely illustrates the very natural acceptance by a border people, who settled down to civilisation at a relatively later date, of the artistic tenets of the two greater peoples who environed them. The Nahua and Maya calendars were in all likelihood evolved from the calendar system of that civilised race which undoubtedly existed on the Mexican plateau prior to the coming of the later Nahua swarms, and which in general is loosely alluded to as the “Toltec.”
The Mexican Year
The Mexican year was a cycle of 365 days, without any intercalary addition or other correction. In course of time it almost lost its seasonal significance because of the omission of the extra hours included in the solar year, and furthermore many of its festivals and occasions were altered by high-priests and rulers to suit their convenience. The Mexican nexiuhilpililztli (binding of years) contained fifty-two years, and ran in two separate cycles—one of fifty-two years of 365 days each, and another of seventy-three groups of 260 days each. The first was of course the solar year, and embraced eighteen periods of twenty days each, called “months” by the old Spanish chroniclers, with five nemontemi (unlucky days) over and above. These days were not intercalated, but were included in the year, and merely overflowed the division of the year into periods of twenty days. The cycle of seventy-three groups of 260 days, subdivided into groups of thirteen days, was called the “birth-cycle.”