"What might lie behind this statement is revealed by a contemporary Mopán Maya tale in which Lord K'in (the sun) goes from his home in the east to the center of the sky and then back to the east again; it appears that he goes clear across the sky because he has placed a mirror at its center.

To interpret the movements of the sun in this manner is to model it on Venus as morning star, which both rises and sets in the east."

(The comments to Popol Vuh)