有则改之，无则加勉. If there is a fault, correct it. If there is none, take it as a spur. The phrase comes from Zhu Xi’s commentary on the Analects, on the passage where Zengzi examines himself on three points each day. Today dictionaries describe it as the attitude to take toward criticism from others: correct the fault if there is one, and use the criticism for self-reflection if there is none.