The first and foremost duty of Aztec Priests was to nourish Tonalli and keep the world moving, the Gods fed and the Sun lit. Priests also sought to win favor with the gods by fasts and sacrifice. One of the most important functions of the priests was to determine which days would be lucky for engaging in activities such as war and baptism. A religious calendar of 260 days provided this information. The dates of ceremonies to honor the gods were determined by a solar calendar of 365 days. Variants of both calendars were developed by earlier Mesoamerican civilizations such as the Olmec, Maya, and Zapotec. The meshing of the two calendars produced a 52-year cycle, at the end of which the Aztec would let their hearth fires go out. To begin the next cycle, they would hold the important “new fire ceremony,” in which priests lit a sacred fire in the chest cavity of a sacrificial victim, and the people rekindled their hearth fires and began feasting.