“This book is magnetic. It has a power, it draws you in across the room.”

Jewish history expert Sharon Liberman Mintz was speaking about arguably the single most important piece of Judaica to come up for sale this century.

Unseen in public for more than 40 years and previously hidden for centuries, the 792-page Codex Sassoon — the oldest nearly complete version of the Hebrew Bible — will go on sale at Sotheby’s in New York on May 16. It is expected to fetch between $30 million and $50 million.

Mintz, the senior Judaica consultant for Sotheby’s New York since 1995, was in London for the beginning of the 1,000-year-old Codex’s “world tour” — which sees it going on display in Dallas, Los Angeles and Tel Aviv before the auction.

For a rapt crowd in the auction house’s London galleries, it was a once-in-a-lifetime opportunity to see the Codex up close, and listen to Mintz explain the history of this extraordinary object.

Written in the Middle East in the ninth century, the Codex disappeared for hundreds of years before resurfacing in 1929. It is astonishingly similar in format to what we use today.

Codex Sassoon The Earliest Most Complete Hebrew Bible Circa 900 09 - Courtesy of Sotheby-s

The Codex Sassoon (Image courtesy of Sotheby's)

For example, “The Song of the Sea”, which appears in Exodus, is traditionally printed in “brickwork form”, with its lines running back and forth across the column. That same layout is there in the Codex Sassoon.

What is really striking about seeing the Hebrew in the Codex is how clear and sharp it is, written in vegetable inks, and easily legible to the modern reader, unlike the Dead Sea Scrolls.

Between the fragments found in the Dead Sea Scrolls and the writing of the Codex Sassoon, there was the 700-year “the silent period” in which there was no standard written form of the Hebrew Bible.

“This Codex standardises and stabilises everything, and totally revolutionised the ability to study and read and understand the Bible,” said Mintz.

The Codex, she said, “was written either in the land of Israel or in Syria. There were communities of scribe-scholars in Tiberias and Jerusalem, and they were studying the Bible carefully and writing the notes [which appear] at the top and the bottom of the pages”. Carbon dating shows that it was written over one to two years, by one single scribe.

A second scholar added supplementary notes, sometimes over-writing the notation of the original scribe. And over the centuries there are tiny repairs to some of the pages, minute stitches in the parchment, lovingly sewn.

In or around the 13th century, the Codex reached an unnamed synagogue in a north-eastern Syrian city called Makisin — “which nobody has ever heard of”.

Makisin changed its name to Markada, but researchers have not found clear evidence of a Jewish community in the area, and certainly not one wealthy enough to hold title to such a valuable book.

Makisin was destroyed, perhaps by the Mongols in the 13th century or by Tamerlane’s troops in 1400. And the Codex, according to a notation in the final pages, was entrusted into the care of a community member, Salama bin Abi al-Fakhr, who was charged with its safekeeping until the rebuilding of the Makisin synagogue.

Codex Sassoon The Earliest Most Complete Hebrew Bible Circa 900 04 - Courtesy of Sotheby-s

(Image courtesy of Sotheby's)

This never happened and then, said Mintz, “the trail goes cold for 500 years”. And suddenly — in 1929 — the Codex resurfaced, offered for sale in Frankfurt, Germany, to a leading scholar called Aron Freimann, chief librarian of the Judaica division of the city’s state library.

Freimann’s papers did not survive the war. He left Frankfurt for America in 1938, but it is not known who offered the Codex to him. Freimann perhaps decided he could not afford it and wrote, instead, to his good friend, David Solomon Sassoon, who had become a renowned collector of Jewish manuscripts and incunabula.

Sassoon bought the Codex for £350. He had it rebound and numbered the pages, affixing inside a bookplate asserting his ownership — and thus giving it the name by which it is known today.

Sassoon died in Islington in 1942, and though much of his collection went to his heirs, eventually they began to sell items in order to meet UK tax obligations. In 1978, the British Rail Pension Fund purchased it for $320,000 — and sold it for $3.19 million in 1989.

The film producer Jacqui Safra thought his uncle would bid for the Codex Sassoon and so pulled out of the British Rail sale. Instead it was bought by a private investor.

But so keen was Safra to acquire the Codex that he offered the investor, identified by the Washington Post as Yecheskel Toporowitch, a further $1 million on top of what he had already paid. Toporowitch agreed.

Safra has owned the Codex Sassoon since 1989. Mintz said: “He enjoyed it, he studied it, he has allowed scholars to study it — this touches him deeply and he’s looking forward to sharing it and finding a new caretaker.”