Note 1102 — Chapter XXIV · MAYA ARTS, CALENDAR, AND HIEROGLYPHICS.
Reading edition
The number 13 may come from the original reckoning by lunations, 26 days being about the time the moon is seen above the horizon in each revolution, 13 days of increase, and 13 of decrease. Perez, in Landa, Relacion, pp. 366-8. Or it may have been a sacred number before the invention of the calendar, being the number of gods of high rank. Brasseur de Bourbourg, Ib.