It is generally agreed that the "Isleworth Mona Lisa" was painted in the early sixteenth century. Those who believe that Leonardo painted it contend that disparate dates proposed for the initiation of the "Mona Lisa" indicate that two different paintings were worked on at different times, with the "Isleworth Mona Lisa" being begun in 1503 and left unfinished, and the Louvre "Mona Lisa" being begun after 1513. Specifically, it is believed by some that Leonardo da Vinci had begun working on a portrait of Lisa del Giocondo, the model of the "Mona Lisa", in Florence by October 1503.