The Thirteen Tones

The thirteen tones, or numbers, are the second cycle of the Maya tzolkin, running alongside the twenty day signs so that each day carries both a number from one to thirteen and a sign, and a given pairing recurs every two hundred and sixty days. Each tone carries a quality, a character or force that colours the day sign it falls with.

The 260-day count formed by the thirteen tones and twenty day signs is attested across Mesoamerica for well over two thousand years, and its origin has been variously linked to the human gestation period, the interval between zenith passages of the Sun at certain latitudes, and the cycle of Venus, though its exact basis is debated.