Xiuhtecuhtli is fire itself given a name and a face, one of the oldest deities attested in central Mexico and known also as Huehueteotl, the old god, worshipped at hearths from the humblest household to the temple precinct of Tenochtitlan. His name joins xihuitl, turquoise, fire and year in a single Nahuatl root, so that the stone the Mexica prized above gold, the flame kept alive in every home, and the passage of time itself are read as one idea. Sahagun's informants describe him as the deity who stands at the centre of the four world directions, the fire in the middle of the house around which the family gathers, and depictions in the codices give him a brazier headdress and the xiuhcoatl, the turquoise fire serpent, as a weapon. His cult reached its most public expression in the Toxiuhmolpilia, the Binding of the Years, held once every fifty two years when the ritual calendar and the solar year returned together to their starting point.
Duran describes priests extinguishing every fire in the valley, climbing the Hill of the Star at Iztapalapa to kindle a new flame on the breast of a war captive at the exact turn of midnight, and runners carrying that single fire back to relight every hearth before dawn, an act read as guaranteeing that the sun would rise again and time would continue. Xiuhtecuhtli's standing among nobles and the elderly followed from this: fire and long life were understood as kin, and the turquoise diadem he wears in the codices signals rulership as much as flame.
Sources Florentine Codex: General History of the Things of New SpainBernardino de Sahagun; translated by Arthur J. O. Anderson and Charles E. Dibble with Book of the Gods and Rites and The Ancient CalendarDiego Duran; translated by Fernando Horcasitas and Doris Heyden