Completed toward the end of the life of Leonardo, who lived from 1452 to 1519, the Mona Lisa has raised innumerable speculations.
Some, including Vinceti, claimed that the woman with the enigmatic smile was a self-portrait, Leonardo Da Vinci in drag.
Others suggested that the sitter was either Caterina Sforza, the illegitimate daughter of Galeazzo Maria Sforza, Duke of Milan; Isabella of Aragon, the Duchess of Milan; or Costanza d'Avalos, Duchess of Francavilla, a mistress of Giuliano de Medici.
In 2005, Veit Probst, director of the Heidelberg University Library, found evidence in notes written in October 1503 in the margin of a book that Leonardo's model was Lisa Gherardini, a member of a minor noble family of rural origins who married the merchant Francesco del Giocondo.
Attempts to solve the enigma around her smile, described by the 16th century artist and writer Giorgio Vasari as "more divine than human," have included theories that the noblewoman was happily pregnant, suffering from asthma, had facial paralysis or that the smile was the result of a compulsive gnashing of teeth.