In ancient times a prophetess who, in a state of ecstasy and under influence of Apollo, prophesized without being consulted. Famous Sibyls are the Cumaean Sibyl and the Erythraean Sibyl, who revealed to Alexander the Great his divine descent.
The Cumaean Sibyl was the earliest of the Sibyls. She was believed to have come from the rest, and resided at Cumae. She owned, according to tradition, nine books of prophecies. When the Roman king Targuin (Tarquinius Priscus) wanted to buy those books he thought the price she asked far too high. The Sibyl threw three books into the fire and doubled the price; this she did again with the next three books, and the king was forced the buy the remaining three books for a price four times as high as the original nine.
The Cumaean Sibyl resided in a still existing dromos at Cumae near Naples, Italy.