http://www.sciencemag.org/news/2018/06/feeding-gods-hundreds-skulls-reveal-massive-scale-human-sacrifice-aztec-capital

The priest quickly sliced into the captive's torso and removed his still-beating heart. That sacrifice, one among thousands performed in the sacred city of Tenochtitlan, would feed the gods and ensure the continued existence of the world.

Death, however, was just the start of the victim's role in the sacrificial ritual, key to the spiritual world of the Mexica people in the 14th to the 16th centuries.