tistic
period rather than getting lost in the minutia of dates and specific works. The Vatican Archives, it
seemed, were cataloged on a similar philosophy. Broad strokes . . .
"Everything in this vault," Langdon said, feeling more confident now, "centuries of material, has to do
with the Crusades. That's this vault's theme." It was all here, he realized. Historical accounts, letters,
artwork, socio-political data, modern analyses. All in one place . . . encouraging a deeper understanding
of a topic. Brilliant.
Vittoria frowned. "But data can relate to multiple themes simultaneously."
"Which is why they cross-reference with proxy markers." Langdon pointed through the glass to the
colorful plastic tabs inserted among the documents. "Those indicate secondary documents located
elsewhere with their primary themes."
"Sure," she said, apparently letting it go. She put her hands on her hips and surveyed the enormous space.
Then she looked at Langdon. "So, Professor, what's the name of this Galileo thing we're looking for?"
Langdon couldn't help but smile. He still couldn't fathom that he was standing in this room. It's in here,
he thought. Somewhere in the dark, it's waiting.
"Follow me," Langdon said. He started briskly down the first aisle, examining the indicator tabs of each
vault. "Remember how I told you about the Path of Illumination? How the Illuminati recruited new
members using an elaborate test?"
"The treasure hunt," Vittoria said, following closely.
"The challenge the Illuminati had was that after they placed the markers, they needed some way to tell the
scientific community the path existed."
"Logical," Vittoria said. "Otherwise nobody would know to look for it."
"Yes, and even if they knew the path existed, scientists would have no way of knowing where the path
began. Rome is huge."
"Okay."
Langdon proceeded down the next aisle, scanning the tabs as he talked. "About fifteen years ago, some
historians at the Sorbonne and I uncovered a series of Illuminati letters filled with references to the
segno."
"The sign. The announcement about the path and where it began."
"Yes. And since then, plenty of Illuminati academics, myself included, have uncovered other references
to the segno. It is accepted theory now that the clue exists and that Galileo mass distributed it to the
scientific community without the Vatican ever knowing."
"How?"
"We're not sure, but most likely printed publications. He published many books and newsletters over the
years."
"That the Vatican no doubt saw. Sounds dangerous."
"True. Nonetheless the segno was distributed."
"But nobody has ever actually found it?"
"No. Oddly though, wherever allusions to the segno appear-Masonic diaries, ancient scientific journals,
Illuminati letters-it is often referred to by a number."
"666?"
Langdon smiled. "Actually it's 503."
"Meaning?"
"None of us could ever figure it out. I became fascinated with 503, trying everything to find meaning in
the number-numerology, map references, latitudes." Langdon reached the end of the aisle, turned the
corner, and hurried to scan the next row of tabs as he spoke. "For many years the only clue seemed to be
that 503 began with the number five . . . one of the sacred Illuminati digits." He paused.
"Something tells me you recently figured it out, and that's why we're here."
"Correct," Langdon said, allowing himself a rare moment of pride in his work. "Are you familiar with a
book by Galileo called Diàlogo?"
"Of course. Famous among scientists as the ultimate scientific sellout."
Sellout wasn't quite the word Langdon would have used, but he knew what Vittoria meant. In the early
1630s, Galileo had wanted to publish a book endorsing the Copernican heliocentric model of the solar
system, but the Vatican would not permit the book's release unless Galileo included equally persuasive
evidence for the church's geocentric model-a model Galileo knew to be dead wrong. Galileo had no
choice but to acquiesce to the church's demands and publish a book giving equal time to both the accurate
and inaccurate models.
"As you probably know," Langdon said, "despite Galileo's compromise, Diàlogo was still seen as
heretical, and the Vatican placed him under house arrest."
"No good deed goes unpunished."
Langdon smiled. "So true. And yet Galileo was persistent. While under house arrest, he secretly wrote a
lesser-known manuscript that scholars often confuse with Diàlogo. That book is called Discorsi."
Vittoria nodded. "I've heard of it. Discourses on the Tides."
Langdon stopped short, amazed she had heard of the obscure publication about planetary motion and its
effect on the tides.
"Hey," she said, "you're talking to an Italian marine physicist whose father worshiped Galileo."
Langdon laughed. Discorsi however was not what they were looking for. Langdon explained that Discorsi
had not been Galileo's only work while under house arrest. Historians believed he had also written an
obscure booklet called Diagramma.
"Diagramma della Verità," Langdon said. "Diagram of Truth."
"Never heard of it."
"I'm not surprised. Diagramma was Galileo's most secretive work-supposedly some sort of treatise on
scientific facts he held to be true but was not allowed to share. Like some of Galileo's previous
manuscripts, Diagramma was smuggled out of Rome by a friend and quietly published in Holland. The
booklet became wildly popular in the European scientific underground. Then the Vatican caught wind of
it and went on a book-burning campaign."
Vittoria now looked intrigued. "And you think Diagramma contained the clue? The segno. The
information about the Path of Illumination."
"Diagramma is how Galileo got the word out. That I'm sure of." Langdon entered the third row of vaults
and continued surveying the indicator tabs. "Archivists have been looking for a copy of Diagramma for
years. But between the Vatican burnings and the booklet's low permanence rating, the booklet has
disappeared off the face of the earth."
"Permanence rating?"
"Durability. Archivists rate documents one through ten for their structural integrity. Diagramma was
printed on sedge papyrus. It's like tissue paper. Life span of no more than a century."
"Why not something stronger?"
"Galileo's behest. To protect his followers. This way any scientists caught with a copy could simply drop
it in water and the booklet would dissolve. It was great for destruction of evidence, but terrible for
archivists. It is believed that only one copy of Diagramma survived beyond the eighteenth century."
"One?" Vittoria looked momentarily starstruck as she glanced around the room. "And it's here?"
"Confiscated from the Netherlands by the Vatican shortly after Galileo's death. I've been petitioning to
see it for years now. Ever since I realized what was in it."
As if reading Langdon's mind, Vittoria moved across the aisle and began scanning the adjacent bay of
vaults, doubling their pace.
"Thanks," he said. "Look for reference tabs that have anything to do with Galileo, science, scientists.
You'll know it when you see it."
"Okay, but you still haven't told me how you figured out Diagramma contained the clue. It had
something to do with the number you kept seeing in Illuminati letters? 503?"
Langdon smiled. "Yes. It took some time, but I finally figured out that 503 is a simple code. It clearly
points to Diagramma."
For an instant Langdon relived his moment of unexpected revelation: August 16. Two years ago. He was
standing lakeside at the wedding of the son of a colleague. Bagpipes droned on the water as the wedding
party made their unique entrance . . . across the lake on a barge. The craft was festooned with flowers and
wreaths. It carried a Roman numeral painted proudly on the hull-DCII.
Puzzled by the marking Langdon asked the father of the bride, "What's with 602?"
"602?"
Langdon pointed to the barge. "DCII is the Roman numeral for 602."
The man laughed. "That's not a Roman numeral. That's the name of the barge."
"The DCII?"
The man nodded. "The Dick and Connie II."
Langdon felt sheepish. Dick and Connie were the wedding couple. The barge obviously had been named
in their honor. "What happened to the DCI?"
The man groaned. "It sank yesterday during the rehearsal luncheon."
Langdon laughed. "Sorry to hear that." He looked back out at the barge. The DCII, he thought. Like a
miniature QEII. A second later, it had hit him.
Now Langdon turned to Vittoria. "503," he said, "as I mentioned, is a code. It's an Illuminati trick for
concealing what was actually intended as a Roman numeral. The number 503 in Roman numerals is-"
"DIII."
Langdon glanced up. "That was fast. Please don't tell me you're an Illuminata."
She laughed. "I use Roman numerals to codify pelagic strata."
Of course, Langdon thought. Don't we all.
Vittoria looked over. "So what is the meaning of DIII?"
"DI and DII and DIII are very old abbreviations. They were used by ancient scientists to distinguish
between the three Galilean documents most commonly confused.
Vittoria drew a quick breath. "Diàlogo . . . Discorsi . . . Diagramma."
"D-one. D-two. D-three. All scientific. All controversial. 503 is DIII. Diagramma. The third of his
books."
Vittoria looked troubled. "But one thing still doesn't make sense. If this segno, this clue, this
advertisement about the Path of Illumination was really in Galileo's Diagramma, why didn't the Vatican
see it when they repossessed all the copies?"
"They may have seen it and not noticed. Remember the Illuminati markers? Hiding things in plain view?
Dissimulation? The segno apparently was hidden the same way-in plain view. Invisible to those who
were not looking for it. And also invisible to those who didn't understand it."
"Meaning?"
"Meaning Galileo hid it well. According to historic record, the segno was revealed in a mode the
Illuminati called lingua pura."
"The pure language?"
"Yes."
"Math