With the fourth world destroyed, the gods assembled in darkness at Teotihuacan to decide who would become the new sun. Tecuciztecatl, a proud and wealthy god, volunteered at once, while Nanahuatzin, a poor, disease marked god, was chosen as his humbler counterpart. Both prepared through penance, then approached the sacrificial fire. Tecuciztecatl, offered the honour of jumping first, hesitated four times, afraid of the flames, until Nanahuatzin leapt in without pause and was consumed.
Shamed, Tecuciztecatl finally followed. From the fire two suns rose into the sky, Nanahuatzin transformed into the sun proper, later called Tonatiuh, and Tecuciztecatl into a second, equally bright light. The gods, judging two suns too much for the world to bear, threw a rabbit into Tecuciztecatl's face, dimming him into the moon, whose markings are still read as that rabbit's form. Even then the new sun would not move across the sky until the assembled gods gave their own blood in sacrifice, an act finally accomplished with the help of the wind god Ehecatl.
From this founding sacrifice the Mexica drew a demanding theological conclusion, that the sun's motion, and therefore the survival of the world itself, depended on a continuing debt of human blood, the ideological foundation for the large scale offerings conducted at temples such as the Templo Mayor. The era carries the calendrical name Nahui Ollin, Four Movement, and Mexica tradition held that this fifth world, like the four before it, was destined to end, in earthquakes.