At the court of the Shogun Iyenari, it was a tense moment. Hokusai, already well established as a prodigiously gifted artist, was competing with a conventional brush-stroke painter in a face-off judged by the shogun personally. Hokusai painted a blue curve on a big piece of paper, chased a chicken across it whose feet had been dipped in red paint, and explained the result to the shogun: it was a landscape showing the Tatsuta River with floating red maple leaves. Hokusai won the competition. The story is well known but the reaction of the conventional brush-stroke artist was not recorded. It's quite likely that he thought Hokusai had done not much more than register an idea, or, as we would say today, a concept. A loser's view, perhaps; though not without substance. If Hokusai had spent his career dipping chickens in red paint, he would have been Yoko Ono.
But Hokusai did a lot more, and the same applies to ever artist we respect, in any field: sometimes they delight us with absurdly simple things, but we expect them to back it up with plenty of evidence that they can do complicated things as well. And anyway, on close examination the absurdly simple thing might turn out to be achieved not entirely without technique. Late in his career Picasso would take ten seconds to turn a bicycle saddle and a pair of handlebars into a bull's head and expect to charge you a fortune for it, but when he was sixteen he could paint a cardinal's full-length portrait that looked better than anything ever signed by Velazquez. You can't tell, just from looking at the bull's head, that it was assembled by a hand commanding infinities of know-how, but you would have been able to tell, from looking at Hokusai's prize-winning picture, that a lot of assurance lay behind the sweep of blue paint, and that he had professionally observed floating red maple leaves long enough to know that the prints of a chicken's red-painted feet would resemble them, as long as the chicken could be induced to move briskly and not just hang about making puddles.