Mona Lisa has been securely identified by Vasari as Lisa Gherardini, wife of the Florentine silk merchant Francesco del Giocondo, and the portrait as the one in the possession of François I now in the Louvre. It was assumed that the picture was painted in Florence after Leonardo returned from his travels with Cesare Borgia in 1503 and before he went back to Milan in 1506. The assumption was verified in 2005 when a librarian at the University of Heidelberg, preparing a copy of the 1477 edition of Cicero's Epistoles ad Familiares for an exhibition, came upon a marginal note by Agostino Vespucci comparing Leonardo with Apelles, in which he notes that Leonardo was then working on a portrait of Lisa del Giocondo. The note is dated 1503.

There is therefore no call for further speculation about who the original of the Mona Lisa might be, and yet it goes on...