CHAPTER 20

Langdon and Sophie move stealthily through the deserted Grand Gallery toward an emergency stairwell after faking Langdon's escape. Langdon worries that Captain Fache may be framing him and wonders whether Fache could have written the message on the floor, but Sophie rejects the idea because the Fibonacci numbers, P.S., Da Vinci references, goddess symbolism, and pentacle are too personal and coherent to be anyone but Saunière.

Sophie explains that Saunière had called her earlier to say he needed to tell her something, so she believes his Louvre message was a final attempt to reach her through Langdon. She also reveals that the pentacle was a childhood joke between them because they played Tarot and Saunière always made her indicator card come from the suit of pentacles. Langdon connects this to sacred feminine symbolism and asks whether Saunière taught her about goddess worship, but Sophie says her grandfather focused more on mathematics, especially PHI and the Divine Proportion.

As they descend the stairs, Langdon's thoughts shift into a memory of teaching at Harvard. He recalls explaining that PHI, approximately 1.618, arises from the Fibonacci sequence and appears throughout nature, human anatomy, art, music, and architecture. In the lecture, Langdon links PHI to Da Vinci, The Vitruvian Man, the pentacle, and the sacred feminine, emphasizing that a pentacle's internal line segments express the Divine Proportion.

Returning from the memory, Langdon stops on the stairs with a sudden realization. The scrambled Fibonacci sequence is not merely a signature or lure; because Fibonacci numbers only make sense in correct order, the disorder itself is a clue. Langdon concludes that the two strange lines of Saunière's message are also out of order.

Sophie initially doubts that Saunière would use something as simple as an anagram, but Langdon explains that anagrams have a long symbolic and mystical tradition. He rearranges the letters of O, Draconian devil and Oh, lame saint, revealing that they form Leonardo da Vinci and The Mona Lisa. Saunière's final message now points them directly toward Da Vinci's famous painting.