Mencius compared humaneness to archery: “The archer corrects himself and then shoots. If he misses, he does not resent the one who beat him. He simply seeks the cause in himself.” In another chapter he says: “Whenever an action does not succeed, seek the cause in oneself.”
The phrase 反求诸己 lives on as an idiom. The Handian dictionary defines it as “to turn back and make demands of oneself, to look for the cause in oneself.”