The entrance to the archives themselves was off a courtyard called the Cortile del Belvedere, within the Vatican complex.

Claudio, it turned out, regularly researched here, and he briskly showed me the areas to which visiting scholars were allowed access: a ground-floor room called the sala di studio, and the Index Room, which actually contained a thousand indices, many themselves very old.

Claudio walked me across to a rattling elevator, which took us down to what he called the bunker. This was the Manuscript Depository, built in the seventies to cope with the great inward flood of material that the Archives had had to cope with in the postwar period. It was an underground library, a basic, unadorned, ugly place, with shelving spread over two stories, and mesh flooring and steel stairs connecting everything. Some of the shelves were locked, holding sensitive material, and others were empty, waiting for more material yet to come.

We went through into the Parchment Room, where some of the more famous documents were stored for display. They were held in chests of drawers, each waist-high, with ten glass-topped drawers in each. These pieces could be stunning—often in Latin, some illuminated, others covered by wax seals.

Claudio kept up an engaging and practiced patter. From its very earliest days, even in the days of persecution, the church in Rome had adopted the imperial habit of record keeping. The first archives had been called the scrinium sanctum, a bit of language that startled me with recognition. But the archives were far from complete. The first collections had been burned around A.D. 300 by the Emperor Diocletian. When Christianity had become the religion of the Empire, the accretion of records had begun again. Little had survived, however, from the bloody turbulence of the first millennium.

In the fourteenth century the popes had, for a time, been exiled to France, and in the fifteenth a period of infighting had peaked with three rival popes rampaging around Europe—“A bibliographer’s nightmare,” said Claudio laconically. The later popes had started trying to unify the archives in the sixteenth century. But when Napoléon had taken Italy, he hauled the whole lot away to France for a few years, doing still more damage in the process . . .

“But all we have is here,” Claudio said. “There are letters from popes as far back as Leo the First, from the fifth century, who faced down Attila the Hun. We have diplomas from Byzantine emperors. The correspondence of Joan of Arc. Reports of papal enclaves, accusations of witchcraft and other skulduggery in high places, sexual secrets of kings, queens, bishops, and a few popes. The records of the Spanish Inquisition, details of the trial of Galileo . . . Even the letter from England asking for the dissolution of the first marriage of Henry the Eighth.”

“And somewhere in all this,” I said, “is the true story of the Order. Or at least as the Vatican saw it.”