From 《
楚辞·
渔父》: the exiled
屈原 will not bend to a muddy world, and the fisherman rows off singing
沧浪之水清兮,
可以濯吾缨;
沧浪之水浊兮,
可以濯吾足: clear water is for washing the hat strings, muddy water for washing the feet, so go along with the times. The
孟子 has the same song from a child, with
我 for
吾, and Confucius draws another lesson from it: the water itself decides what it is used for.