三國時期（220－280AD），吳國有一個叫呂蒙的將軍。呂蒙出生在窮苦人家，小時候沒有機會上學。長大後他參了軍，看書的時間更少了。一次，吳國的皇帝召見呂蒙，對他說：”現在你是大將軍了，應該多看看書 開闊眼界。”呂蒙回答道："軍中的事務這麼忙，我恐怕沒有時間讀書。" 吳國的皇帝說："你難道比我還忙嗎？我常常抽空閱讀兵書，從中得到了不少好處。多看看前人的經驗之談，你會有更大的進步。"呂蒙接受了皇帝的建議，從此開始專心閱讀，看了很多歷史和軍事書籍。
Look at someone with new eyes/knock the socks off someone
Lu Meng was a general of Wu during the Three Kingdoms Period (220-280AD). He was born in such a poor family that he did not get any chance to go to school when he was a child. However, there was still less time for reading when he served in the army after he grew up. Once the king of Wu summoned Lu Meng and said to him, "Since you are now a general in power, you had better read some books to widen your horizon." Lu Meng answered, "I am so busy with military affairs that I am afraid I have little time to read.” The King said, "Are you busier than I am? Even I often find time to read books on the art of war and gain many benefits from them. To read more about the experience left by our ancestors will make you progress.” Lu Meng then did according to what the king said. He concentrated on reading history and military writings.
One day, Military Governor Lu Su visited Lu Meng and was surprised to find that Lu Meng had become very knowledgeable. Lu Su, who held Lu Meng in contempt earlier, said, "I did not expect that you would know so much besides fighting! You are not the one you used to be!” Lu Meng replied, "You should look at a person with new eyes even only after three days' separation."
Today, when a person does something that causes others to see him differently, we can say that people "look at him with new eyes."