The Rose Line； Silas thought。 The brotherhood hid the keystone at the Rose Line。
Earlier tonight； when Silas told the Teacher that the Priory keystone was hidden inside Saint…Sulpice； the Teacher had sounded doubtful。 But when Silas added that the brothers had all given him a precise location； with relation to a brass line running through Saint…Sulpice； the Teacher had gasped with revelation。 〃You speak of the Rose Line！〃
The Teacher quickly told Silas of Saint…Sulpice's famed architectural oddity—a strip of brass that segmented the sanctuary on a perfect north…south axis。 It was an ancient sundial of sorts； a vestige of the pagan temple that had once stood on this very spot。 The sun's rays； shining through the oculus on the south wall； moved farther down the line every day； indicating the passage of time； from solstice to solstice。
The north…south stripe had been known as the Rose Line。 For centuries； the symbol of the Rose had been associated with maps and guiding souls in the proper direction。 The pass Rose—drawn on almost every map—indicated North； East； South； and West。 Originally known as the Wind Rose； it denoted the directions of the thirty…two winds； blowing from the directions of eight major winds； eight half…winds； and sixteen quarter…winds。 When diagrammed inside a circle； these thirty…two points of the pass perfectly resembled a traditional thirty…two petal rose bloom。 To this day； the fundamental navigational tool was still known as a pass Rose； its northernmost direction still marked by an arrowhead。。。 or； more monly； the symbol of the fleur…de…lis。
On a globe； a Rose Line—also called a meridian or longitude—was any imaginary line drawn from the North Pole to the South Pole。 There were； of course； an infinite number of Rose Lines because every point on the globe could have a longitude drawn through it connecting north and south poles。 The question for early navigators was which of these lines would be called the Rose Line—the zero longitude—the line from which all other longitudes on earth would be measured。
Today that line was in Greenwich； England。
But it had not always been。
Long before the establishment of Greenwich as the prime meridian； the zero longitude of the entire world had passed directly through Paris； and through the Church of Saint…Sulpice。 The brass marker in Saint…Sulpice was a memorial to the world's first prime meridian； and although Greenwich had stripped Paris of the honor in 1888； the original Rose Line was still visible today。
〃And so the legend is true；〃 the Teacher had told Silas。 〃The Priory keystone has been said to lie 'beneath the Sign of the Rose。' 〃
Now； still on his knees in a pew； Silas glanced around the church and listened to make sure no one was there。 For a moment； he thought he heard a rustling in the choir balcony。 He turned and gazed up for several seconds。 Nothing。
I am alone。
Standing now； he faced the altar and genuflected three times。 Then he turned left and followed the brass line due north toward the obelisk。
At that moment； at Leonardo da Vinci International Airport in Rome； the jolt of tires hitting the runway startled Bishop Aringarosa from his slumber。
I drifted off； he thought； impressed he was relaxed enough to sleep。
〃Benvenuto a Roma；〃 the inter announced。
Sitting up； Aringarosa straightened his black cassock and allowed himself a rare smile。 This was one trip he had been happy to make。 I have been on the defensive for too long。 Tonight； however； the rules had changed。 Only five months ago； Aringarosa had feared for the future of the Faith。 Now； as if by the will of God； the solution had presented itself。
Divine intervention。
If all went as planned tonight in Paris； Aringarosa would soon be in possession of something that would make him the most powerful man in Christendom。
CHAPTER 23
Sophie arrived breathless outside the large wooden doors of the Salle des Etats—the room that housed the Mona Lisa。 Before entering； she gazed reluctantly farther down the hall； twenty yards or so； to the spot where her grandfather's body still lay under the spotlight。
The remorse that gripped her was powerful and sudden； a deep sadness laced with guilt。 The man had reached out to her so many times over the past ten years； and yet Sophie had remained immovable—leaving his letters and packages unopened in a bottom drawer and denying his efforts to see her。 He lied to me！ Kept appalling secrets！ What was I supposed to do？ And so she had blocked him out。 pletely。
Now her grandfather was dead； and he was talking to her from the grave。
The Mona Lisa。
She reached for the huge wooden doors； and pushed。 The entryway yawned open。 Sophie stood on the threshold a moment； scanning the large rectangular chamber beyond。 It too was bathed in a soft red light。 The Salle des Etats was one of this museum's rare culs…de…sac—a dead end and the only room off the middle of the Grand Gallery。 This door； the chamber's sole point of entry； faced a dominating fifteen…foot Botticelli on the far wall。 Beneath it； centered on the parquet floor； an immense octagonal viewing divan served as a wele respite for thousands of visitors to rest their legs while they admired the Louvre's most valuable asset。
Even before Sophie entered； though； she knew she was missing something。 A black light。 She gazed down the hall at her grandfather under the lights in the distance； surrounded by electronic gear。 If he had written anything in here； he almost certainly would have written it with the watermark stylus。
Taking a deep breath； Sophie hurried down to the well…lit crime scene。 Unable to look at her grandfather； she focused solely on the PTS tools。 Finding a small ultraviolet penlight； she slipped it in the pocket of her sweater and hurried back up the hallway toward the open doors of the Salle des Etats。
Sophie turned the corner and stepped over the threshold。 Her entrance； however； was met by an unexpected sound of muffled footsteps racing toward her from inside the chamber。 There's someone in here！ A ghostly figure emerged suddenly from out of the reddish haze。 Sophie jumped back。
〃There you are！〃 Langdon's hoarse whisper cut the air as his silhouette slid to a stop in front of her。
Her relief was only momentary。 〃Robert； I told you to get out of here！ If Fache—〃
〃Where were you？〃
〃I had to get the black light；〃 she whispered； holding it up。 〃If my grandfather left me a message—〃
〃Sophie； listen。〃 Langdon caught his breath as his blue eyes held her firmly。 〃The letters P。S。。。。 do they mean anything else to you？ Anything at all？〃
Afraid their voices might echo down the hall； Sophie pulled him into the Salle des Etats and closed the enormous twin doors silently； sealing them inside。 〃I told you； the initials mean Princess Sophie。〃
〃I know； but did you ever see them anywhere else？ Did your grandfather ever use P。S。 in any other way？ As a monogram； or maybe on stationery or a personal item？〃
The question startled her。 How would Robert know that？ Sophie had indeed seen the initials P。S。 once before； in a kind of monogram。 It was the day before her ninth birthday。 She was secretly bing the house； searching for hidden birthday presents。 Even then； she could not bear secrets kept from her。 What did Grand…père get for me this year？ She dug through cupboards and drawers。 Did he get me the doll I wanted？ Where would he hide it？
Finding nothing in the entire house； Sophie mustered the courage to sneak into her grandfather's bedroom。 The room was off…limits to her； but her grandfather was downstairs asleep on the couch。
I'll just take a fast peek！
Tiptoeing across the creaky wood floor to his closet； Sophie peered on the shelves behind his clothing。 Nothing。 Next she looked under the bed。 Still nothing。 Moving to his bureau； she opened the drawers and one by one began pawing carefully through them。 There must be something for me here！ As she reached the bottom drawer； she still had not found any hint of a doll。 Dejected； she opened the final drawer and pulled aside some black clothes she had never seen him wear。 She was about to close the drawer when her eyes caught a glint of gold in the back of the drawer。 It looked like a pocket watch chain； but she knew he didn't wear one。 Her heart raced as she realized what it must be。
A necklace！
Sophie carefully pulled the chain from the drawer。 To her surprise； on the end was a brilliant gold key。 Heavy and shimmering。 Spellbound； she held it up。 It looked like no key she had ever seen。 Most keys were flat with jagged teeth； but this one had a triangular column with little pockmarks all over it。 Its large golden head was in the shape of a cross； but not a normal cross。 This was an even…armed one； like a plus sign。 Embossed in the middle of the cross was a strange symbol—two letters intertwined with some kind of flowery design。
〃P。S。；〃 she whispered； scowling as she read the letters。 Whatever could this be？
〃Sophie？〃 her grandfather spoke from the doorway。
Startled； she spun； dropping the key on the floor with a loud clang。 She stared down at the key； afraid to look up at her grandfather's face。 〃I。。。 was looking for my birthday present；〃 she said； hanging her head； knowing she had betrayed his trust。
For what seemed like an eternity； her