From 《
楚辞·
渔父》(Chuci, 'The Fisherman,' attributed traditionally to
屈原 Qu Yuan or his circle, 3rd c. BCE). After Qu Yuan laments his exile, the fisherman sings and rows off:
沧浪之水清兮,
可以濯吾缨;
沧浪之水浊兮,
可以濯吾足 (When the waters of Canglang are clear, I may wash my hat-strings; when muddy, I may wash my feet). Also quoted by Confucius in 《
孟子·
离娄上》, treating it as the principle that the world decides whether honor is possible.
缨 = the chinstrap tassel of an official's hat, symbol of office.