Vittoria shook her head. "Nothing that looks purely mathematical. I'm skimming… but none of this reads like a clue."

Langdon continued translating his folios with increasing difficulty. His Italian skills were rocky at best, and the tiny penmanship and archaic language was making it slow going. Vittoria reached the end of her stack before Langdon and looked disheartened as she flipped the pages back over. She hunkered down for another more intense inspection.

When he reached the end of his current folio, he lifted the spatula to flip the page. As he aligned the blade with the next page, he fumbled, having difficulty holding the tool steady. Minutes later, he looked down and realized he had abandoned his spatula and was turning pages by hand. Oops, he thought, feeling vaguely criminal. The lack of oxygen was affecting his inhibitions. Looks like I'll burn in archivist's hell.

"About damn time," Vittoria choked when she saw Langdon turning pages by hand. She dropped her spatula and followed suit.

Inside Archive Vault 10 Robert Langdon recited Italian numbers as he scanned the calligraphy before him. Mille…centi…uno, duo, tre…cincuanta. I need a numerical reference! Anything, damnit!

"Any luck?"

When Langdon finished his final page, he cursed under his breath and looked over at Vittoria. She was scowling, squinting at something on one of her folios. "What is it?" he asked.

"This page has a footnote. It's obscured in a crease."

Vittoria did not look up. "Did you have any footnotes on your pages?"

"Not that I noticed. Why?"

His hopes faded. "It's supposed to be math. Lingua pura."

Vittoria shook her head. "Text. One line. Very small printing. Almost illegible."

Langdon tried to see what she was looking at, but all he could make out was the page number in the upper right-hand corner of the sheet. Folio 5. It took a moment for the coincidence to register, and even when it did the connection seemed vague. Folio Five. Five, Pythagoras, pentagrams, Illuminati. Langdon wondered if the Illuminati would have chosen page five on which to hide their clue. Through the reddish fog surrounding them, Langdon sensed a tiny ray of hope. "Is the footnote mathematical?"

"Yeah, I know." She hesitated. "I think you'll want to hear this, though." Langdon sensed excitement in her voice.

"Go ahead."

As the words sank in, Langdon felt his delirium pierced by an instant of clarity. The path of light is laid, the sacred test. He had no idea how it helped them, but the line was as direct a reference to the Path of Illumination as he could imagine. Path of light. Sacred test. His head felt like an engine revving on bad fuel. "Are you sure of the translation?"

Squinting at the folio, Vittoria read the line. "The path of light is laid, the sacred test."

The words were nothing like what Langdon had imagined. "I'm sorry?"

"Path of light?" Langdon felt his posture straightening.

"That's what it says. Path of light."

Vittoria pushed the document over to him, and Langdon read the minuscule printing at the bottom of the page."The path of light is laid, the sacred test. English? What isEnglish doing in an Italian book?"

For an instant, Langdon thought the acoustics in the chamber had affected his hearing."English?"

Vittoria hesitated. "Actually…" She glanced over at him with a strange look. "It's not technically a translation. The line is written inEnglish."

Vittoria repeated the line. "The path of light is laid, the sacred test."

"So you're saying maybe Galileo considered Englishla lingua pura because it was the one language the Vatican did not control?"

Vittoria shrugged. She too was looking tipsy. "Maybe English is what they meant by thelingua pura? It's considered the international language of science. It's all we speak at CERN."

"Yes. Or maybe by putting the clue in English, Galileo was subtly restricting the readership away from the Vatican."

"But this was in the 1600s," Langdon argued. "Nobody spoke English in Italy, not even --" He stopped short, realizing what he was about to say. "Not even… theclergy." Langdon's academic mind hummed in high gear. "In the 1600s," he said, talking faster now,"English was one language the Vatican had not yet embraced. They dealt in Italian, Latin, German, even Spanish and French, but English was totally foreign inside the Vatican. They considered English a polluted, free-thinkers language for profane men like Chaucer and Shakespeare." Langdon flashed suddenly on the Illuminati brands of Earth, Air, Fire, Water. The legend that the brands were inEnglish now made a bizarre kind of sense.

She's right, Langdon thought. The line didn't help in any way. But as he spoke the phrase again in his mind, a strange fact hit him. Now that's odd, he thought. What are the chances of that?

"We need to get out of here," Vittoria said, sounding hoarse.

Vittoria looked lost. "Iambic who?"

For an instant Langdon was back at Phillips Exeter Academy sitting in a Saturday morning English class. Hell on earth. The school baseball star, Peter Greer, was having trouble remembering the number of couplets necessary for a line of Shakespearean iambic pentameter. Their professor, an animated schoolmaster named Bissell, leapt onto the table and bellowed, "Penta-meter, Greer! Think of home plate! A penta-gon! Five sides! Penta! Penta! Penta! Jeeeesh!"

"But it's not even a clue," Vittoria argued."The path of light is laid, the sacred test? What the hell does that mean?"

Langdon wasn't listening. The path of light is laid, the sacred test. "It's a damn line of iambic pentameter," he said suddenly, counting the syllables again. "Five couplets of alternating stressed and unstressed syllables."

Langdon wheeled to see her rotating the folio upside down. He felt a knot in his gut. Not again. "There's no way that line is an ambigram!"

A moment later, another realization sent a numbing sensation down his legs. Iambic pentameter, on account of its simplicity, was often called "pure verse" or "pure meter."La lingua pura? Could this have been the pure language the Illuminati had been referring to? The path of light is laid, the sacred test…

You're reaching! Langdon told himself, trying to push it from his mind. A meaningless coincidence! But the thought stuck. Five…for Pythagoras and the pentagram. Two…for the duality of all things.

"Uh oh," Vittoria said.

"It's what?"

Five couplets, Langdon thought. Each couplet, by definition, havingtwo syllables. He could not believe in his entire career he had never made the connection. Iambic pentameter was a symmetrical meter based on the sacred Illuminati numbers of 5 and 2!

"No, it's not an ambigram… but it's…" She kept turning the document, 90 degrees at every turn.

Vittoria did not relinquish the page. She kept turning the page in quarter turns. "I didn't see the lines before because they're on the edges." She cocked her head over the last line. "Huh. You know what? Galileo didn't even write this."

Vittoria looked up. "It's not theonly line."

"There's a different line on every margin. Top, bottom, left, and right. I think it's a poem."

"Four lines?" Langdon bristled with excitement. Galileo was a poet? "Let me see!"

"There's another?"

"What!"

"JohnMilton?" The influential English poet who wroteParadise Lost was a contemporary of Galileo's and a savant who conspiracy buffs put at the top of their list of Illuminati suspects. Milton's alleged affiliation with Galileo's Illuminati was one legend Langdon suspected was true. Not only had Milton made a well-documented 1638 pilgrimage to Rome to "commune with enlightened men," but he had held meetings with Galileo during the scientist's house arrest, meetings portrayed in many Renaissance paintings, including Annibale Gatti's famousGalileo and Milton, which hung even now in the IMSS Museum in Florence.

"The poem is signed John Milton."

She smiled tightly. "Good, now can we get the hell out of here?"

"Milton knew Galileo, didn't he?" Vittoria said, finally pushing the folio over to Langdon. "Maybe he wrote the poem as a favor?"

Langdon clenched his teeth as he took the sheathed document. Leaving it flat on the table, he read the line at the top. Then he rotated the page 90 degrees, reading the line in the right margin. Another twist, and he read the bottom. Another twist, the left. A final twist completed the circle. There were four lines in all. The first line Vittoria had found was actually the third line of the poem. Utterly agape, he read the four lines again, clockwise in sequence: top, right, bottom, left. When he was done, he exhaled. There was no doubt in his mind. "You found it, Ms. Vetra."

"I have to copy these lines down. I need to find a pencil and paper."

But Vittoria was already gone.

Vittoria shook her head. "Forget it, professor. No time to play scribe. Mickey's ticking." She took the page from him and headed for the door.

Langdon stood up. "You can't take that outside! It's a --"