Very Intelligent in Youth

Kung Rung was a famous minister of the Eastern Han dynasty. He was a 20th generation descendant of Confucius, and from his youth was very intelligent.

When Kung Rung was ten years old, he went to Loyang with his father. He heard that the only guests allowed to visit the home of Loyang's prefect, Li Yuan-li, were either relatives or talented and famous people. Kung Rung wanted to find out what kind of person Li Yuan-li was, so he went to the prefect's home and told the gatekeepers that he was a relative. When Li Yuan-li saw that a child had come to see him, he asked, "How are you related to me?" Kung Rung very politely answered, "Although you and I are not related, my ancestor Confucius used to ask your ancestor Lau-tz questions regarding etiquette. Does that not make us old friends?" When Li Yuan-li's guests heard such a small child answer so well, they all praised Kung Rung's intelligence. Only the senior official Chen Wei said, "Intelligence in youth does not necessarily mean success as an adult." On hearing this, Kung Rung said, "I'll bet Official Chen was very intelligent as a youth, right?

To say that a person is "very intelligent in youth" is to imply that though is smart as a child, he will not have a very bright future.

小時了了

東漢時的名臣孔融，小時就很聰明，曾因讓梨給哥哥而名聞一時。十歲那年
跟著父親到京城，聽說當時的河南太守李元禮除了親戚和名人之外，不肯便接見賓客。

愈是如此，孔融愈想看看他到底是怎樣的一個人，於是便獨自來到這位太守的府門前，對守門的人說：「我是李太守的親戚，請你進去通報一聲。」李太守見是一個小孩，懷疑的問：「你和我有什麼親戚關係？」
孔融從容的回答道：「我的老祖先孔夫子，和你的老祖先老子有師友的交情，我和你也是世交呀！」
李太守和座上的賓客，都十分驚訝孔融的聰明和勇敢。偏有一個叫陳韙的中大夫不以為然的說：「小時了了，大未必佳(小的時候雖然聰明，長大卻未必是這樣)。」
孔融立即反駁說：「我想陳大夫小的時候，一定很聰明囉！」座上的賓客哄堂大笑，更加佩服孔融的機智。

「小時了了」本來是形容人小時就很聰明，卻因這段故事，而變成諷刺別人的話。