 The existence of a 9 nights cycle in Mesoamerican calendrics was first discovered in 1904 by Eduard Seler.The Aztec names of the Deities are known because their names are glossed in the Codex Telleriano-Remensis and Codex Tudela.Seler argued that the 9 lords each corresponded to one of the nine levels of the under world and ruled the corresponding hour of the night time, this argument has not generally been accepted, since the evidence suggests that the lord of a given night ruled over that entire night.