These officials, at the command of the senate, consulted the Sibylline books in order to discover, not exact predictions of definite future events, but the religious observances necessary to avert extraordinary calamities (pestilence, earthquake) and to expiate prodigies in cases where the national deities were unable, or unwilling, to help. Only the interpretation of the oracle which was considered suitable to the emergency was made known to the public, not the oracle itself.
But when Greek deities were introduced into Rome on the advice of the Sibylline books (in 495 B.C., on the occasion of a severe drought), Demeter, the Greek goddess of seed and harvest, whose worship was already common in Sicily and Lower Italy, usurped the place of Ceres in Rome, or rather, to Ceres were added the religious rites which the Greeks paid to Demeter, and the mythological incidents which originated with her.
Her festival at Rome, the Floralia, instituted 2 3 8 B.C. by order of the Sibylline books and at first held irregularly, became annual after 173.
The well-known story of Tarquinius's repeated refusal and final consent to purchase the Sibylline books has its origin in the fact that the building of the temple of Jupiter Capitolinus, in which they were kept, was ascribed to him.
The story of the Sibylline books in Rome, on the other hand, shows the growth of the idea of authority.
