Jin official Ji Tan came from a noble family that had managed historical records for generations. His surname "Ji" originated from this hereditary duty. But by his time, he no longer oversaw these archives and knew little of Jin's history.
In the autumn of 527 BCE, the wife of King Jing of the Eastern Zhou dynasty, Queen Mu, passed away. According to Zhou ritual, each vassal state was required to send a special envoy to offer condolences and present precious gifts.
When envoys Xun Li and Ji Tan of the Jin state arrived at the Zhou capital bearing no valuable gifts, King Jing of Zhou grew displeased and decided to pressure them. He hosted a banquet and deliberately ordered attendants to pour wine for the two Jin envoys using a bronze pot newly presented by the Duke of Lu.
After three rounds of wine, King Jing of Zhou, emboldened by drink, boasted to the Jin envoy Xun Li about the bronze vessel from Lu, saying, "Don't you think this bronze piece from Lu is precious?" "Truly precious," Xun Li replied vaguely. The king's face darkened as he pressed, "Every other state has sent tribute to the royal court—why is Jin the only one holding back?"
Xun Li was momentarily at a loss for words and signaled to Ji Tan to respond. Caught off guard, Ji Tan replied, "Your Majesty, when the feudal lords were first enfeoffed, they all received gifts from the royal house, so offering tribute is only natural. However, our humble state is nestled deep in the mountains, bordering barbarian tribes, and has never received such imperial favors. We barely have enough resources to defend against these tribes—how could we possibly have treasures to present to Your Majesty?"
Upon hearing this, King Jing of Zhou grew even more displeased and scolded, "You are too forgetful
Then, King Jing of Zhou cited many irrefutable facts, leaving Ji Tan speechless. The king further mocked, "Wasn't your ancestor in charge of Jin's cultural relics and records? As a descendant of the archivist, how could you be so ignorant of Jin's history?"
Ji Tan and Xun Li, utterly humiliated, could no longer bear to stay and quickly took their leave.
King Jing of Zhou watched the two men walk away and laughed smugly, "Tan's descendants will likely never enjoy official rank again! He has actually forgotten his ancestors!" Later, people used the idiom "forgetting one's ancestors" to describe forgetting one's roots or being ignorant of one's own history.
Source: *Zuo Zhuan*, "Duke Zhao's Fifteenth Year"
Meaning of the Idiom: Later, the Chinese idiom "数典忘祖" came to describe forgetting one's roots or being ignorant of one's own history.