Leonardo da Vinci was a Renaissance genius. Not only did he paint masterpieces of art, but he was an obsessive scientist and inventor, dreaming up complex machines centuries ahead of his time, including parachutes, armored tanks, hang gliders and robots. On the 500th anniversary of Leonardo’s death, with the help of biographer Walter Isaacson, NOVA investigates the secrets of Leonardo’s success. How did his scientific curiosity, from dissections of cadavers to studies of optics, shape his genius and help him create perhaps the most famous painting of all time, the "Mona Lisa"?