Ha! I was finally able to connect two things with each other that I had been looking to connect for quite a while. Back in August 2016, I posted about then-new and highly significant finds that came to light during that year’s excavations at the sanctuary of Zeus at Mt. Lykaion, located in the southwestern tip of Arcadia, where Zeus was born, raised and worshipped. A human burial with an East-West orientation was found and excavated in the middle of the altar and next to a platform carved into the rock. Of course, the idea of human sacrifice in ancient Hellas (very, very ancient Hellas) rose again.

When it happened, I knew I had read about human sacrifice on that altar before, but I couldn't for the life of me remember where. Some ancient source. Somewhere. I gave up, eventually, and then I bloody found it! It was mentioned in Pausanias, Description of Greece.

“For Cecrops was the first to name Zeus the Supreme god, and refused to sacrifice anything that had life in it, but burnt instead on the altar the national cakes which the Athenians still call pelanoi. But Lycaon brought a human baby to the altar of Lycaean Zeus, and sacrificed it, pouring out its blood upon the altar, and according to the legend immediately after the sacrifice he was changed from a man to a wolf (Lycos).

[8.2.4] I for my part believe this story; it has been a legend among the Arcadians from of old, and it has the additional merit of probability. For the men of those days, because of their righteousness and piety, were guests of the gods, eating at the same board; the good were openly honored by the gods, and sinners were openly visited with their wrath. Nay, in those days men were changed to gods, who down to the present day have honors paid to them – Aristaeus, Britomartis of Crete, Heracles the son of Alcmena, Amphiaraus the son of Oicles, and besides these Polydeuces and Castor.

[8.2.5] So one might believe that Lycaon was turned into a beast, and Niobe, the daughter of Tantalus, into a stone. But at the present time, when sin has grown to such a height and has been spreading over every land and every city, no longer do men turn into gods, except in the flattering words addressed to despots, and the wrath of the gods is reserved until the sinners have departed to the next world.

[8.2.6] All through the ages, many events that have occurred in the past, and even some that occur to-day, have been generally discredited because of the lies built up on a foundation of fact. It is said, for instance, that ever since the time of Lycaon a man has changed into a wolf at the sacrifice to Lycaean Zeus, but that the change is not for life; if, when he is a wolf, he abstains from human flesh, after nine years he becomes a man again, but if he tastes human flesh he remains a beast for ever.

[8.2.7] Similarly too it is said that Niobe on Mount Sipylus sheds tears in the season of summer. I have also heard that the griffins have spots like the leopard, and that the Tritons speak with human voice, though others say that they blow through a shell that has been bored. Those who like to listen to the miraculous are themselves apt to add to the marvel, and so they ruin truth by mixing it with falsehood.”
[Pausanias, 8.2.3-7]