The Sibylline Books (Latin: Libri Sibyllini) were a collection of oracular utterances, set out in Greek hexameters, that according to tradition were purchased from a sibyl by the last king of Rome, Tarquinius Superbus, and were consulted at momentous crises through the history of the Republic and the Empire. Only fragments have survived, the rest being lost or deliberately destroyed.
The Sibylline Books should not be confused with the so-called Sibylline Oracles, twelve books of prophecies thought to be of Judaeo-Christian origin.
According to the Roman tradition, the oldest collection of Sibylline books appears to have been made about the time of Solon and Cyrus at Gergis on Mount Ida in the Troad; it was attributed to the Hellespontine Sibyl and was preserved in the temple of Apollo at Gergis. From Gergis the collection passed to Erythrae, where it became famous as the oracles of the Erythraean Sibyl. It would appear to have been this very collection that found its way to Cumae (see the Cumaean Sibyl) and from Cumae to Rome.
The story of the acquisition of the Sibylline Books by Tarquinius is one of the famous legendary elements of Roman history. The Cumaean Sibyl offered to Tarquinius nine books of these prophecies; and as the king declined to purchase them, owing to the exorbitant price she demanded, she burned three and offered the remaining six to Tarquinius at the same stiff price, which he again refused, whereupon she burned three more and repeated her offer. Tarquinius then relented and purchased the last three at the full original price and had them preserved in a vault beneath the Capitoline temple of Jupiter. The story is alluded to in Varro's lost books quoted in Lactantius Institutiones Divinae (I: 6) and by Origen.