Ehecatl, wind, is read by the tonalamatl as a day of breath, speech and motion, and Sahagun's fourth book records the wind days as changeable and fickle in augury, the sign's restless nature read directly into the fortune of those born beneath it, gifted talkers whose course was as hard to fix as the air itself. Ehecatl is also the name the codices give to Quetzalcoatl in his wind aspect, one of the feathered serpent's several distinct manifestations, so the day sign and a major god's alternate identity share a single word, a coincidence Nahua thought treated as meaningful rather than accidental, since wind and the god who set the sun and moon in motion after their creation at Teotihuacan were understood as expressions of the same restless, animating force.
The sign's association with speech gave it a further reading beyond mere inconstancy: a wind day's child was expected to speak persuasively, a gift as double edged in the readers' judgment as any other, since words that move easily can as readily mislead as convince. Wind's place as the second sign, following the caiman's solid earth, reads across Mesoamerican thought generally as air following ground, motion following the fixed, one of several such pairings the twenty sign sequence carries between neighbouring days.