“The sibyl, with frenzied mouth uttering things not to be laughed at, unadorned and unperfumed, yet reaches to a thousand years with her voice....”
Heraclitus, 5th century BCE
In ancient Greece, the Sibyls channeled the prophetic wisdom of the gods. They would usually descend into a cave or someplace where fetid air was conducive to trances and hallucinations. Channeling of the sort was witnessed by Aeneas.