Human sacrifice appears to have been a strong cultural theme for the ancient Aztecs. However, the records of how many exactly were sacrificed in Aztec religious rituals are unclear, with some numbers possibly being inflated to make them appear more barbaric and thus justify the Spanish invasion.
Do we have any sources that can unambiguously and concretely tell us how many people the Aztecs sacrificed? (either an annual tally of sorts, or of certain events, like the re-consecration of the Great Pyramid of Tenochtitlan)
Do we know when the Aztecs stopped sacrificing people and why? Did they only stop when they were finally conquered by the Spanish?
EDIT: not sure why my post was flaired as Shopping, if a mod sees this feel free to edit the flair to something more appropriate.
not sure why my post was flaired as Shopping
Well, Durán does say Tlacaelel declared that:
Our god will not be made to wait until new wars appear. He will find a way, a marketplace where he will go with his army to buy victims, men for him to eat. And this will be a good thing, for it will be as if he has his maize cakes hot from the griddle -- tortilla from a nearby place, hot and ready to eat whenever he wishes them. Let our people, let our army, go to this marketplace to buy with our blood, with our heads and hearts, and with our lives the precious stones, jades, and rubies, and splendid long shining feathers for our wondrous Huitzilopochtli.
For further reading you may be interested in the FAQ section on Mesoamerican Human Sacrifice and Blood Sacrifice or, since this is a topic that comes up often, my fairly recent comments on:
As for the continuance of practices, there is the very famous case of Don Carlos Ometochtzin, a noble from the ruling family of Texcoco. He was burned at the stake on the orders of Bishop Zumárraga in 1539 for heresy, though any direct connection to sacrifice was tenuous. What got Ometochtzin in trouble was combination of semi-openly advocating for an abandonment of Christianity and a return to traditional Nahua practices, spurred on by the lack of miraculous action by the former to end a drought in the region. Although what really seemed to get him in trouble was the fact that this stance gave his dynastic and political rivals an excuse to denounce him and get him removed from the line of inheritance.
Patricia Lopes Don, who has written extensively on this topic including in her monograph, Bonfires of Culture: Franciscans, Indigenous Leaders, and the Inquisition in Early Mexico, posits that the severe action Zumárraga took of condemning Don Carlos to death was actually a bit of a shock to both the Nahua nobility and the Catholic authorities. The continuation of Nahua religious practices (which, despite the popular misconception, were not just sacrifices) seems to have been a bit of an open secret. While there were friars who advocated for the harsh punishment of inquisitorial executions, both secular and ecclesiastic authorities worried that such a stance would foment massive rebellion, particularly if more of the Nahua nobility were targeted for execution and/or seizure of their estates. So instead of pyres going up across New Spain, Zumárraga received a letter of reprimand, which insisted he pursue his evangelism more "with love than with rigor."