信陵君救趙
信陵君殺晉鄙，
救邯鄲，破秦人，
存趙國，趙王至郊迎。
唐睢謂信陵君曰：
「臣聞之曰，事有不可知者，
有不可不知者；
有不可忘者，有不可不忘者。」
信陵君曰：「何謂也？」
對曰：
「人之憎我也，不可不知也；
吾憎人也，不可得而知也。
人之有德於我也，不可忘也；
吾有德於人也，不可不忘也。
今君殺晉鄙，
救邯鄲，攻秦人，
存趙國，此大德也。
今趙王至郊迎，卒然見趙王，
臣願君之忘之也。」
信陵君曰：
「無忌謹受教。」

──《戰國策‧魏策四》

Tang Ju Persuades Lord Xinling
Lord Xinling killed General Jin Bi, saved the city of Handan,
defeated the army of Qin, and saved the state of Zhao.

Before the King of Zhao arrived in the countryside to welcome
him in person, Tang Ju said to Lord Xinling, “I, your subject, have heard the following saying:

There are things that cannot be known, and those that must be known.

There are things that cannot be forgotten, and those that must be forgotten.”

Lord Xinling asked, “How so?”

He replied, “If others detest me, it must be known. If I detest others, it cannot be known.
If others do me a favor, it cannot be forgotten. If I do others a favor, it must be forgotten.”

Today, my Lord has slain Jin Bi, saved Handan, defeated the army of Qin, and saved the state of Zhao, a great favor indeed.
Now, the King of Zhao has come to the countryside to welcome you in person.
As soon as you meet the King of Zhao, I your subject, sincerely hope my Lord will forget it.”

To which Lord Xiling said, “Inevitably, I respectfully receive your teachings.”

── from Zhan Guo Ce (Strategies of the Warring States)