Few people are as famous as Leonardo da Vinci. His paintings have become icons of civilization, his notebooks the quintessential expression of the creative and scientific mind. He is who we mean when we say ‘Renaissance Man.’ But he had a fatal flaw. For all his artistic and inventive genius, he rarely finished anything. Even his most famous work, the Mona Lisa, was never  ‘completed.’  Vasari, a contemporary of Leonardo’s, wrote in his biography of Leonardo (in Lives of the Most Eminent Italian Architects, Painters, and Sculptors, 1550), that “Leonardo undertook to execute, for Francesco del Giocondo, the portrait of Mona Lisa, his wife; and after toiling over it for four years, he left it unfinished.”[1]