To keep the gods happy with bloodshed, so that the sun would continue coming up each morning. Aztecs were a religious group, war bound up with religion. It was supposed to be honorable to be sacrificed to the gods.
Fine Art by Rene Magritte - "Dangerous Liaisons," oil on canvas, X This is an interesting painting. I like how the artist distorted the body using a mirror- could definitely use this as a source of inspiration for the gesture/identity drawing.