Trecena 12 opens on 1 Cuetzpalin, the lizard, under the patronage of Itztlacoliuhqui, the curved obsidian blade, the frost lord, a hardened and punitive aspect of Tezcatlipoca associated in the sources with self-inflicted blindness, with the killing frost that ends a growing season, and with the punishment of sin. Those born in the lizard week read as hardy, the sources say, able to recover, prosper and endure, keeping their footing where others fall, while the frost patron above the sign tempers this generally favourable reading with severity, a week of endurance rewarded only through hardship rather than given freely.
Itztlacoliuhqui's myth, in the accounts that preserve it, tells of a deity blinded, by his own hand in some versions, as punishment for a transgression, a self-inflicted severity that mirrors frost's own indiscriminate damage to crops regardless of a farmer's effort, and his patronage of a trecena whose sign, the lizard, is elsewhere read for regeneration and survival, sets endurance against punishment as the week's central theme. The lizard's own capacity to regrow a lost tail, a piece of natural history Nahua thought folded directly into Cuetzpalin's symbolism, gave this trecena's hardy, recovering augury a concrete image the readers could point to when explaining the sign to a client.