〃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 monly confused。
Vittoria drew a quick breath。 〃Diаlogo 。 。 。 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。〃
〃Mathematics？〃
〃That's my guess。 Seems pretty obvious。 Galileo was a scientist after all； and he was writing for scientists。 Math would be a logical language in which to lay out the clue。 The booklet is called Diagramma； so mathematical diagrams may also be part of the code。〃
Vittoria sounded only slightly more hopeful。 〃I suppose Galileo could have created some sort of mathematical code that went unnoticed by the clergy。〃
〃You don't sound sold；〃 Langdon said； moving down the row。
〃I'm not。 Mainly because you aren't。 If you were so sure about DIII； why didn't you publish？ Then someone who did have access to the Vatican Archives could have e in here and checked out Diagramma a long time ago。〃
〃I didn't want to publish；〃 Langdon said。 〃I had worked hard to find the information and…〃 He stopped himself； embarrassed。
〃You wanted the glory。〃
Langdon felt himself flush。 〃In a manner of speaking。 It's just that…〃
〃Don't look so embarrassed。 You're talking to a scientist。 Publish or perish。 At CERN we call it 'Substantiate or suffocate。' 〃
〃It wasn't only wanting to be the first。 I was also concerned that if the wrong people found out about the information in Diagramma； it might disappear。〃
〃The wrong people being the Vatican？〃
〃Not that they are wrong； per se； but the church has always downplayed the Illuminati threat。 In the early 1900s the Vatican went so far as to say the Illuminati were a figment of overactive imaginations。 The clergy felt； and perhaps rightly so； that the last thing Christians needed to know was that there was a very powerful anti…Christian movement infiltrating their banks； politics； and universities。〃 Present tense； Robert； he reminded himself。 There IS a powerful anti…Christian force infiltrating their banks； politics； and universities。
〃So you think the Vatican would have buried any evidence corroborating the Illuminati threat？〃
〃Quite possibly。 Any threat； real or imagined； weakens faith in the church's power。〃
〃One more question。〃 Vittoria stopped short and looked at him like he was an alien。 〃Are you serious？〃
Langdon stopped。 〃What do you mean？〃
〃I mean is this really your plan to save the day？〃
Langdon wasn't sure whether he saw amused pity or sheer terror in her eyes。 〃You mean finding Diagramma？〃
〃No； I mean finding Diagramma； locating a four…hundred…year…old segno； deciphering some mathematical code； and following an ancient trail of art that only the most brilliant scientists in history have ever been able to follow 。 。 。 all in the next four hours。〃
Langdon shrugged。 〃I'm open to other suggestions。〃
50
Robert Langdon stood outside Archive Vault 9 and read the labels on the stacks。
BRAHE 。 。 。 CLAVIUS 。 。 。 COPERNICUS 。 。 。 KEPLER 。 。 。 NEWTON 。 。 。
As he read the names again； he felt a sudden uneasiness。 Here are the scientists 。 。 。 but where is Galileo？
He turned to Vittoria； who was checking the contents of a nearby vault。 〃I found the right theme； but Galileo's missing。〃
〃No he isn't；〃 she said； frowning as she motioned to the next vault。 〃He's over here。 But I hope you brought your reading glasses； because this entire vault is his。〃
Langdon ran over。 Vittoria was right。 Every indictor tab in Vault 10 carried the same keyword。
IL PROCESO GALILEANO
Langdon let out a low whistle； now realizing why Galileo had his own vault。 〃The Galileo Affair；〃 he marveled； peering through the glass at the dark outlines of the stacks。 〃The longest and most expensive legal proceeding in Vatican history。 Fourteen years and six hundred million lire。 It's all here。〃
〃Have a few legal documents。〃
〃I guess lawyers haven't evolved much over the centuries。〃
〃Neither have sharks。〃
Langdon strode to a large yellow button on the side of the vault。 He pressed it； and a bank of overhead lights hummed on inside。 The lights were deep red； turning the cube into a glowing crimson cell 。 。 。 a maze of towering shelves。
〃My God；〃 Vittoria said； looking spooked。 〃Are we tanning or working？〃
〃Parchment and vellum fades； so vault lighting is always done with dark lights。〃
〃You could go mad in here。〃
Or worse； Langdon thought； moving toward the vault's sole entrance。 〃A quick word of warning。 Oxygen is an oxidant； so hermetic vaults contain very little of it。 It's a partial vacuum inside。 Your breathing will feel strained。〃
〃Hey； if old cardinals can survive it。〃
True； Langdon thought。 May we be as lucky。
The vault entrance was a single electronic revolving door。 Langdon noted the mon arrangement of four access buttons on the door's inner shaft； one accessible from each partment。 When a button was pressed； the motorized door would kick into gear and make the conventional half rotation before grinding to a halt…a standard procedure to preserve the integrity of the inner atmosphere。
〃After I'm in；〃 Langdon said； 〃just press the button and follow me through。 There's only eight percent humidity inside； so be prepared to feel some dry mouth。〃
Langdon stepped into the rotating partment and pressed the button。 The door buzzed loudly and began to rotate。 As he followed its motion； Langdon prepared his body for the physical shock that always acpanied the first few seconds in a hermetic vault。 Entering a sealed archive was like going from sea level to 20；000 f