Agostino Vespucci

[5] The identity of the young woman in Leonardo's Mona Lisa had been difficult to ascertain due to a lack of decisive contemporary sources of information about the painting.

This changed upon the discovery of a comment written by Vespucci in the margin of a 1477 edition of Cicero's Epistulae ad Familiares, now held by the Heidelberg University Library.

Ita Leonardus Vincius facit in omnibus suis picturis, ut enim caput Lise del Giocondo et Anne matris virginis.

")[7] In the comment, Vespucci notes a similarity of style between Leonardo and the renowned ancient Greek painter Apelles, in that both artists would first render the head and shoulders of subjects in extraordinary detail before continuing with the rest of the painting.

The inclusion of the name and date allowed validation with a later known (but often unreliable) source published in 1550 and written by art historian Giorgio Vasari, who states that during this period Leonardo had taken a commission from Francesco del Giocondo to paint his wife, "Mona Lisa.