Message at the Mona Lisa

Sophie and Langdon go to the Salle des Etats to examine the Mona Lisa. Using a black light, Sophie finds a message scrawled on the protective glass: 'So dark the con of man.' Langdon explains this is a proclamation of the Priory of Sion's philosophy about the Church's suppression of the sacred feminine. While there, Sophie also discovers a gold key hidden behind the nearby painting, Madonna of the Rocks. The key bears the Priory's seal: a fleur-de-lis and the initials P.S.