My money is on Sybil of Cumae, in the 6th century BC. Not a co-incidence that Pythagoras and many other enlightened ones came along at this time. It comes in periodic waves from the center of the Milky Way....
Despite the Bible saying that fortune tellers are forbidden, Michelangelo was allowed to paint this very well known fortune-teller in the Sistine Chapel. This means that in Medieval times they must have known who wrote this Gnostic book.
From http://www.philipcoppens.com/cumae.html
"The story of the Sibyl of Cumae was well-known. Dante wrote about it and Michelangelo painted her on the ceiling of the Sistine Chapel. Virgil said that Cumae had been the site where Daedalus had come to when fleeing from the kingdom of Minos. “He dared to trust his life to the sky, floating off on swiftly driving wings towards the cold stars of the north, the Greater and Lesser Bears, by a route no man had ever gone before, until at last he was hovering lightly in the air above the citadel of Chalcidian Cumae. Here he first returned to earth, dedicating to Phoebus Apollo the wings that had oared him through the sky, and founding a huge temple. On its doors were depicted the death of Androgeos, son of Minos, and then the Athenians, the descendants of Cecrops, ordered to pay a cruel penalty and yield up each year the living bodies of seven of their sons.”
In ancient times, Virgil was not the only one to write about the Sibyl and the site; this is what Strabo had to say about it: “Near Kume [Cumae] is Cape Misenom, and between them is Lake Akherousia, a kind of shoal-water estuary of the sea … also Gulf Aornos [Avernus] … The pole prior to my time were wont to make Aornos the setting of the fabulous story of the Homeric Nykeia [Odysseus' journey to the Underworld]; and, what is more, writers tell us that there actually was an Oracle of the Dead [of the gods Hades and Persephone] here and that Odysseus visited it "
http://www.artgallerypaintings.net/2009/10/michelangelo-cuman-sibyl.html
"Another legend of the Cumæan sibyl has to do with the Roman emperor Tarquin. The sibyl came to him one day with nine books of oracles, which she wished him to buy. The price was exorbitant, and the emperor refused her demand. She then went away, burned three of the books, and, returning with the remaining six, made the same demand. Again her offer was refused, and again she burned three books and returned, still requiring the original price for the three that were left. Tarquin now consulted the soothsayers, and, acting upon their advice, bought the books, which were found to contain directions concerning the religion and policy of Rome.
For many years they were held sacred, and were carefully preserved in the temple of Jupiter in the Capitol, under the care of official guardians. At length the temple was destroyed by fire, and the original sibylline books perished. In the following centuries they were replaced by scattered papers, collected from time to time in various parts of the empire, purporting to be the writings of the sibyl. These sibylline leaves, as they were called, contained passages supposed to be prophetic of the coming of Christ, and this is why the Cumæan sibyl is placed by Michelangelo among the prophets."
And from this blog... http://wheresjesus.multiply.com/journal/item/1869
And this is how it found its way into the NT as related by Tony Bushby in "The Crucifixion of Truth" pages 40 to 47 - with the odd irrelevant gaps.
The Origin of the Book of Revelation
"....Herophile was one of several women who prophesied under the supposed inspiration of some deity, and delivered her prophecies in a frenzied state. She was considered the greatest seer of Pagan antiquity and her 'heather oracles' (Note - Catholic Encycolpaedia) played a most significant part in early Christian times. "With the discovery of the 'Vatican Scrolls' it is possible to prove the Sibyl's influence reached deeply into the New Testament for one of those scrolls was written by her and later became the Book of Revelation."
Then follows the story of the purchase by the Senate in 510BCE.
Bushby continued... "....her volumes were kept in a specially carved marble chest personally commissioned by Tarquin himself and lined with the 'purple of kings'. (Note - Pliny). Priests were appointed to interpret the writings and scribes were assigned to reproduce exact copies
The original collection was jealously guarded in the Temple of Jupiter Capitolinus and frequently consulted by priests for guidance before prayers were addressed to the God of Fire and the Goddess of Agriculture. In times of peril and disaster, the original copies were entrusted to curators who were assisted by two Greek interpreters to read the oracles aloud to the Senate.
Roman historian Tacitus (c.56-126) recorded that statues of the Sibyl were idolised and 'invocations' were made and lustral water was brought to wash her cella' and statue in the Capitol. Sometimes the statues were ceremoniously taken to the sea and washed there. (Note: Annals of Tacitus).
In such awe was Herophile held by the early presbyters that St.Justin Martyr recorded that he made the long overland trip to Cumae to see for himself where she once lived and related how he apprehensively entered the Cave from which her oracles were given.
St.Justin referred without reserve to her writings and asserted that those who denied her offended God. Clement of Alexandria (160 - 215) also quoted freely from the Sibyl's books and even represented St.Paul as appealing to her writings. (Note - Stromata VI).
Clement cited the Sibyl as the 'greatest of all prophetesses' and called her 'the prophetess of the Hebrews'. More remarkably, he quoted the 'Torah and the Sibylline Books in the same sentence. (Note Exhortations IV).
Irenaeus said she was the 'one who announces the counsels or plans of the gods of Egypt', and clearly believed her oracles were divinely inspired. He stated: 'With lips inspired, she utters words that were mirthless, without ornament, and without perfume, but through the power of god her voice reaches down a thousand years.' (Note - Iranaeus of Lyons).
The Sibyl's writings also had considerable influence on presbyter Lactantius (d.328) and St.Augustine, the Bishop of Hippo, quoted at length from her oracles in 'De Civitae Dei'. (Note - (Xviii 23).
A second century opponent to the presbyterian movement, Celsus (c.180) was moved to ridicule the early sermonizer's frequent use of her psychic predictions in writings that later became Christian Gospels. So common was their belief in the Sibylline predictions that Celsus called presbyters the 'Sibyllistai', believers in sibyls, or sibyl-mongers. The Sibyl's works were regarded as 'the mouthpiece of God' because they were believed to contain all directions needed to worship any of the Egyptian Gods. Later Roman kings and emperors saw Apollo Palatinus as the equal of Osiris and overlaid his name as the source of the Sibyl's enlightened words. Her predictive writings were recognized at Rome as one of the most efficacious instruments in Roman religion and were observed and accepted by all Romans. It was believed the Sibylline Books were 'possessed with the spirit of divination' and they subsequently became the 'Bible of the Romans.' (Note Dictionary of Greek and Roman Antiquities).
The originals perished in the fire that destroyed the Temple of Capitolinus in 83 BC and were immediately replaced by copies from other temples, unlike the occasion when original copies of the Old Testament were burnt and replaced by Ezra rewriting from memory. (Note - 2 Edras 14:21).
There is much more to come. But will take a break here. Stay tuned as we see just why and how the Sibyl's books became Revelation.