Quetzalcoatl and Tezcatlipoca represent the bright and dark aspects of the Creator. The earth herself is the nourisher of life; but she is also the burial ground of the dead. One purpose of this myth is to validate the Aztec custom of sacrificing live human hearts.
The gods Quetzalcoatl and Tezcatlipoca brought the earth goddess Tlalteuctli down from on high. All of the joints of her body were filled with eyes and mouths biting like wild beasts. Before they got down, there was water already below, upon which the goddess then moved back and forth. They did not know who created it.
They said to each other, "We must make the earth." So saying, they changed themselves into two great serpents, one of whom seized the goddess from the right hand down to the left foot, the other from the left hand down to the right foot. As they tightened their grip, she broke in the middle. The half with the shoulders became the earth. The remaining half they brought to the sky--which greatly displeased the other gods.
Afterward, to compensate the earth goddess for the damage those two had inflicted upon her, all the gods came down to console her, ordaining that all the produce required for human life would issue from her. From her hair they made trees, flowers and grasses; from her skin, very fine grasses and tiny flowers; from her eyes, wells and fountains, and small caves; from her mouth, rivers and large caves; from her nose, valleys and mountains; from her shoulders, mountains.
Sometimes at night this goddess wails, thirsting for human hearts. She will not be silent until she receives them. Nor will she bear fruit unless she is watered with human blood.