All ancient societies looked to prophecy and divination to ensure that their beliefs and activities were consistent with the will of the gods. Cosmic order could only be maintained by living a life in harmony with God.
Among the Romans, no prophetic oracle was more important or famous than the Sibyl, the prophetess of Cumae. The Sibyl was an office — like a high priestess — rather than a specific individual.
Throughout the ancient world at different times there were many women who were said to have been Sibyls, including a legendary Jewish Sibyl, the daughter-in-law of Noah, who is said to have lived at the time of the Tower of Babel.
For the Romans, however, the most venerated Sibyl prophesied from a sacred cave-temple at Cumae, near modern Naples in Italy.
The appearance of Sibylline oracles in Roman society dates back to the beginning of Roman history. According to legends, king Tarquinius Superbus (c. 535-496 BCE) was approached by a ragged old woman who had nine scrolls she claimed were the prophecies of the Sibyl, for which she demanded three hundred gold pieces.
Tarquinius, thinking the woman a fraud and despising this gift of the gods, refused to pay the outrageous sum. Thereupon the old woman burned three of the scrolls in the nearby fire, turned again to the king and asked three hundred gold pieces for the remaining six. Convinced that the old woman was mad, Tarquinius again refused, upon which the crone burned three more scrolls, again demanding the same three hundred gold pieces for the final three scrolls.
Realizing that the woman was the Sibyl herself, Tarquinius frantically agreed to pay the full sum. The three surviving scrolls of the Sibyl were thereafter carefully preserved in the Capitoline temple of Rome as the most sacred books of the Romans. These oracular scrolls were regularly consulted by a body of 10 special priests for prophetic guidance in major policy decisions. However, the Romans always recognized that they lacked the original complete collection of oracles and, consequently, it was always understood that their interpretations were fallible. (Lactantius, "Divine Institutes," 1.6)
This pagan Sibyl of Cumae was thought to have prophesied under the inspiration of Apollo, the god of divination, whose priestess she was.
She continued to prophesy at Cumae for many centuries, with collections of her oracles added to the original three scrolls of Tarquinius. The most famous description of the oracular method of the Sibyl comes from the Roman national epic, Virgil's "Aeneid" (6.10). After demanding the sacrifice of seven bulls and seven ewes from the hero Aeneas, the Sibyl entered into an ecstatic state.
"As she spoke neither her face nor hue went untransformed, nor did her hair stay neatly bound: her breast heaved, her wild heart grew large with passion. She seemed taller to their eyes, sounding now no longer like a mortal, since she had felt the god's power breathing near."
Thereupon, under the inspiration of Apollo, she prophesied of the future of Aeneas and Rome.
One would have expected Christians and Jews to reject and denounce this pagan prophetess. And many did so. Other early Christians, however, interpreted some of the Sibylline oracles as divinely inspired prophecies of the coming of Jesus — especially the Sibylline prophecy of a future savior of Rome found in Virgil's fourth "Eclogue."
They quoted passages from these oracles to pagans as proof that even their own sacred books prophesied of Christ. The Sibyl's prophecies thus began to be seen by many Christians as having been inspired, at least in part, by the Holy Spirit, and they were later quoted by some early Christian apologists and fathers, including St. Augustine ("City of God," 18.23). Following this ancient tradition, she most famously appears in Michelangelo's Sistine Chapel murals beside prophets of the Old Testament.
This Christian acceptance of some of the Sibyl's prophecies guaranteed their survival, although the extant books of the Sibylline oracles were heavily edited and interpolated by both Christians and Jews.
The remarkable history of the Sibyls is recounted in H. W. Parke, "Sibyls and Sibylline Prophecy" (Routledge, 1988). The surviving 14 books of Christianized Sibylline oracles have been translated in James Charlesworth, "The Old Testament Pseudepigrapha" (1983), 1:317-472.