What is "ixtlilton"

Ixtlilton ( ,The Little Black One) in aztec mythology is the god of medicine and healing, and therefore was often alluded to as the brother of Macuilxochitl}, the god of well-being or good luck. Ixtlilton was a gentle god, who emanated from an obsidian mask which brought darkness and peaceful sleep to children in their beds at night.