He painted two of the most famous pictures on earth and treated them as side projects. His real work was 7,000 pages of machines that wouldn't fly for four centuries.
Leonardo da Vinci finished fewer than twenty paintings and more than seven thousand pages of notes — on flight, water, war, anatomy, and machines that existed nowhere but on paper. The paintings made him immortal; the notebooks made him a prophet. He drew the helicopter four hundred years before it flew, the parachute three centuries before it opened, the tank before gunpowder had finished its first century of war.
