Rippled Surface, by M.C. Escher (1950), and a koan
"Chiyono studied Zen for many years under Bukkõ of Engaku. Still, she could not attain the fruits of meditation. At last one moonlit night she was carrying water in an old wooden pail girdered with bamboo. The bamboo broke, and the bottom fell out of the pail. At that moment, she was set free. Chiyono said, ‘No more water in the pail, no more moon in the water.’"