Trecena (13-day period) Calli
The thirteen day period (trecena) that starts with day 1-Calli (House) is ruled by Itzpapalotl. The 13 days of this trecena are governed by the conflict between culture and nature: the native desire of human beings to maintain a lineage of customs and beliefs is periodically disrupted by the evolutionary leaps of nature. In this sense, nature is represented as the house into which we are born and culture as the house into which we move. These are 13 days of struggling to decide which house is really home. With every step forward, the warrior still stands at the center of the crossroads: the heart must be trained if it is to be a reliable compass. These are good days to focus on the future; bad days to focus on the past.