The Sibylline Oracles were a set of books of prophecy set down by the Sibyl and kept by the Sibylline Sisterhood for generations after. When the Pyroviles began to influence the Sisterhood, the Oracles were largely ignored as false prophecy due to the new vision the Pyroviles had for Earth.
The thirteenth book foretold that the appearance of the Blue Box, a temple made of wood, would be in a time of storms and fire and betrayal. They were presumably lost with the Sisterhood when Vesuvius erupted and destroyed Pompeii. (TV: The Fires of Pompeii)