« On Presidential Ambitions »

According to tradition, the emperor, having heard that Hsiu-yu was a great sage, decided to turn over to him the rule of the state. Hsiu-yu, however, emphatically refused and, believing himself defiled by the very suggestion, went to the river to wash out his ears. When his scrupulous friend Ch'ao-fu saw that the river had been polluted by the emperor's suggestion, he considered it to have become so foul that he would no longer water his bull there or even cross it. (Momoyama).