"All the sacred Mysteries of Asia"

Yourcenar's Hadrian refers to a number of religious cults that were in existence in the eastern part of the Roman Empire. The mysteries of the "cabiri" (or "cabeiri"), for example, on Samothrace, are believed to have a pre-Greek origin, and involved dedications to deities whose names were known only to initiates. The cult of Trophonius was centered around a cave at Labadaea in Boetia, and is mentioned by Pausanias in his Description of Greece 9, 39 - http://www.theoi.com/Pausanias9A.html). Secrecy, fear and ordeal were common elements of these cults, regarded by the Romans with a mixture of fascination and suspicion.