From the White Wolf Wiki, the most complete White Wolf reference

Sometime before the Embrace of Augustus Giovanni, the Antediluvian Cappadocius looked up from his books to hear the complaints of the humans who lived with Cappadocians in Kaymakli. There, he found that the prodigious breeding of his childer had led to a population crisis: anemic humans, disease spread by the constant presence of corpses, and a society on the brink. Realizing that something had to be done, Cappadocius returned to Erciyes and perused the book of Nod.

Then, one night, he called all Cappadocians to join him in Kaymakli, resulting in a pilgrimage of over 12,000 Cainites to a tiny Turkish underground city. For the next week, Cappadocius and his childer Japheth and Caias Koine quizzed his descendants, sending those who answered certain questions in the affirmative deeper into the city. Questions like:

• who among you cannot read or write?
• who among you has not helped build a church?
• who among you does not follow the Via Caeli?

Thousands of Vampires went into the mountain, only to have Cappadocius seal the mountain shut with a millstone and a curse: "Let no child of Caine exit, let no son of Seth enter this place". Condemning thousands of his own descendants to cannibalism, then eternal torpor.

The Feast of Folly is a defining moment in the structure of the clan; the majority of Cappadocians from then on hewed to the stereotype of placid, heaven-obsessed, thanatophiles. Those few stragglers, the Infitiores, left the clan entirely.