This is one of the most famous images in the world, and almost no one knows that the man who made it was over seventy, and believed he was only just getting started... It's The Great Wave off Kanagawa, by Katsushika Hokusai, made in the early 1830s. A wall of water rises over three narrow boats, its crest breaking into claws of white foam, while the men inside bow their heads and hold on. And far in the distance, so small you might miss it, sits Mount Fuji, the most sacred mountain in Japan, framed by the curve of the wave as if it were just another pebble in the sea. By then Hokusai had already been drawing for more than sixty years. He had made thousands of prints and illustrated hundreds of books, more than enough for most people to call it a life's work, but he saw all of it as little more than a warm-up… At seventy-five, he wrote that "until the age of 70, nothing I drew was worthy of notice," and that if he lived to a hundred and ten, "every dot and every stroke will be as though alive." He signed it "Old Man Mad about Painting." He didn't make it to a hundred and ten. He died at nearly ninety, still working, still sure his best was ahead of him. And his last words, recorded by his daughter, were not about what he'd done, but about what he still wanted to do. He asked for five more years of life, "then I'll manage to become a true artist." Most of us spend our lives believing our best years are behind us. The man who made the most famous wave in history spent his believing they hadn't arrived yet…