Interesting in relation to “lost books” as a trope.

Source (re: the Books – the Oracles are something different):

An old woman, possibly a Cumaean Sibyl, offered to Tarquinius nine books of these prophecies at an exorbitant price; when the king declined to purchase them, she burned three and offered the remaining six to Tarquinius at the same price, which he again refused. Thereupon, she burned three more and repeated her offer, maintaining the same price. Tarquinius then consulted the Augurs whose importance in Roman history is averred by Livy. The Augurs deplored the loss of the six books and urged purchase of the remaining three. Tarquinius then purchased the last three at the full original price, and had them preserved in a sacred vault beneath the Capitoline temple of Jupiter.

And:

The Roman Senate kept tight control over the Sibylline Books,[2] and entrusted them to the care of two patricians. In 367 BC, the number of custodians was increased to ten, five patricians and five plebeians, who were called the decemviri sacris faciundis. Subsequently, probably in the time of Sulla, their number was increased to fifteen, the quindecimviri sacris faciundis. They were usually ex-consuls or ex-praetors. They held office for life, and were exempt from all other public duties. They had the responsibility of keeping the books in safety and secrecy. The 15 individuals were custodians of the Sibylline Books that were kept on the Palatine. These officials, at the command of the Senate, consulted the Sibylline Books in order to discover not exact predictions of definite future events in the form of prophecy, but the religious observances necessary to avert extraordinary calamities and to expiate ominous prodigies (comets and earthquakes, showers of stones, plague, and the like).

One more:

The books were kept in the Temple of Jupiter on the Capitol, and, when the temple burned in 83 BC, they were lost. The Roman Senate sent envoys in 76 BC to replace them with a collection of similar oracular sayings, in particular collected from Ilium, Erythrae, Samos, Sicily, and Africa.[4]

As distinguished from the Oracles:

The Oracles are nevertheless thought by modern scholars to be anonymous compilations that assumed their final form in the fifth century, after the Sibylline Books perished. They are a miscellaneous collection of Jewish and Christian portents of future disasters…

Further to the oracles, sometimes called the Pseudo-Sibylline Oracles (which is a helpful name to indicate the distinction between the two sets):

They are not to be confused with the original Sibylline Books of the ancient Etruscans and Romans which were burned by order of the Roman general Flavius Stilicho in the 4th century AD. Instead, the text is an “odd pastiche” of Hellenistic and Roman mythology interspersed with Jewish, Gnostic and early Christian legend.[1]

Still confusing:

Some have suggested that the surviving texts may include some fragments or remnants of the Sibylline Books with a legendary provenance from the Cumaean Sibyl, which had been kept in temples in Rome. The original oracular books, kept in Rome, were accidentally destroyed in a fire in 83 BC, which resulted in an attempt in 76 BC to recollect them when the Roman senate sent envoys throughout the world to discover copies. This official copy existed until at least AD 405, but little is known of their contents.

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