Trecena 13 opens on 1 Ollin, movement, under the patronage of Tlazolteotl, the earth goddess called eater of filth, patron of the once in a lifetime confession rite, neyolmelahualiztli, the straightening of the heart, through which a penitent could clear serious transgression before a priest acting in her name. Sahagun's informants read the movement week's children toward fortune or ruin with little middle ground, an augury of extremes fitting for the sign that names Nahui Ollin, four movement, the present cosmic age the Mexica believed themselves to be living within and which their own cosmology held would eventually end in earthquake, the sign's own violent, unstable meaning built directly into the era's name.
A week of turning points, favourable to the decisive by the readers' judgment, its patronage by a goddess whose whole cult centred on clearing old transgression to make a fresh start fits the movement sign's theme of dramatic change precisely: both goddess and sign concern the passage from one state to a decisively different one, whether through confession's clearing of the past or the cosmic age's eventual violent renewal. Tlazolteotl's patronage here, as trecena patron, is a distinct role from her separate standing as the seventh of the nine Lords of the Night, the two offices assigned independently in the surviving codices.