Trecena 17 runs from 1 Atl through 13 Cipactli, crocodile, its span carrying water, dog, monkey, grass, reed, jaguar, eagle, vulture, movement, flint and rain before closing on the very sign, Cipactli, that opened the entire tonalpohualli at Trecena 1, though now carrying the number thirteen rather than one, a closing that brings the count's day sign vocabulary full circle without yet ending the twenty trecena sequence itself, which still has three weeks left to run. This return to Cipactli near the count's end, achieved through the same modular arithmetic that governs every trecena's thirteen day span, would have given a diviner working the full tonalamatl a sense of the count folding back toward its own beginning even while the specific augury attached to this closing day, thirteen rather than one, remained the water week's own rather than a repeat of Trecena 1's fortunate opening reading.
Chalchiuhtotolin's difficult patronage over this trecena continues the demanding stretch that includes Trecena 15 under Itzpapalotl a few weeks earlier, a pattern the tonalpouhque's clients would have learned to anticipate as the count moved through its final third toward the more favourable close in Trecenas 19 and 20.