SHE PRESENTS an unresolved riddle after almost 500 years. Her identity remains uncertain; her smile is still an enigma. She is regarded by some as a femme fatale, and thought by others chaste. Even her beauty is debatable.
The Mona Lisa may be the world's most famous painting, the most analysed, romanticised, satirised and appropriated, but she is also unknowable. She returns our gaze, her secrets intact. "We feel perturbed in her presence," wrote the novelist and critic, Theophile Gautier, "by her aura of superiority."
Nowadays it is not easy to gain first-hand acquaintance. She hangs in the Louvre in a large gallery of Venetian paintings. Donald Sassoon points out that the unprepared visitor, seeing the crowd and cameras, might assume that their object is not a painting but a living celebrity. Like them, the Mona Lisa needs protection. Since 1974 she has been housed in a special container, set in concrete, behind two sheets of bullet-proof triple-laminated glass. In two years' time, when we reach the presumed 500th anniversary of her birth, she will be given a room of her own.
The first to mention her was Vasari. In his monumental account of Italian painters, sculptors and architects, he reported her physiognomy in minute detail. The errors are puzzling until you learn that he never saw the picture.
Much else in Vasari's account has been unpicked, including the identity of the sitter. He tells us that she was Lisa Gherardini, the wife of Francesco del Giocondo - Monna Lisa. ("Monna" is a contraction of Madonna - my lady - and "Mona" the erroneous spelling used in English.) But the notion that she was just a Florentine housewife does not content everyone. Various arguments have been put forward to give her a more aristocratic or idealised identity.
The problem of identification is compounded by Leonardo's decision to keep the portrait. When he left Italy in 1516 to become court decorator for …