Everyone thinks of Leonardo da Vinci as the paragon of Renaissance virtue. He could paint, design, and use intuition as an aid to creativity, when he felt like doing so. But a closer look at the record paints a picture of a chronic procrastinator, a man of dubious reliability, and an idler who was more preoccupied with his daydreams than with perfecting his craft. He had genius, of course. But that is never enough. Harness, discipline, and application are far more important.