SIBYLLINE ORACLES. In Greek tradition (accepted by the Romans not later than the fourth century BCE and by the Jews not later than the second) a sibyl is an old woman who utters ecstatic predictions of woe. The etymology of the name is unknown. In Greece the earliest mention of the term is found in the writings of the philosopher Heraclitus about 500 BCE, though the figure of the sibyl and perhaps some kind of oracles attributed to her were probably known from the eighth century BCE on. In the following years the tradition of sibylline oracles became well established (and was caricatured by Aristophanes in late-fifth-century BCE Athens).

The sibyls were thought to wander through the world and to attain an extraordinary age—as much as a thousand years. But Delphi, Samos, Erythrae in Ionia, Marpessus in Troas, and Cumae and Tibur in Italy each had...