English Original
Lü Meng was a general of the state of Wu during the Three Kingdoms period. Born into poverty, he received no formal education in his youth and had little time for reading even after joining the military.
Once, the King of Wu summoned Lü Meng and advised him, "Now that you are a general in command, you should read more to broaden your horizons."
Lü Meng replied, "I am too occupied with military affairs to find time for reading."
The King said, "Are you busier than I am? I still make time to study military texts and benefit greatly from them. Learning from the wisdom of our ancestors will help you improve."
Taking the King's advice to heart, Lü Meng devoted himself to studying history and military strategy. One day, Military Governor Lu Su visited Lü Meng and was astonished to find him remarkably knowledgeable. Lu Su, who had previously held Lü Meng in contempt, exclaimed, "I never expected you to be so learned beyond military matters! You are not the man you used to be!"
Lü Meng responded, "One should look at a person with a new eye even after a separation of just three days."
This conversation gave rise to the idiom Guā mù xiāng kàn (or Guā mù xiāng dài). It is used to express astonishment at someone's fabulous progress or transformation, implying that one should renew their respect for that person.
中文翻译
吕蒙是三国时期吴国的一位将军。他出身贫寒，年少时没有机会接受教育，从军后也几乎没有时间读书。
一次，吴王召见吕蒙，对他说：“你如今身居要职，应当多读些书来开阔眼界。”
吕蒙回答：“我军务繁忙，恐怕没有时间读书。”
吴王说：“你比我还忙吗？我尚且经常抽空研读兵书，获益匪浅。多学习前人留下的经验，会让你进步。”
吕蒙听从了吴王的建议，潜心研读史书和兵书。一日，都督鲁肃拜访吕蒙，惊讶地发现他变得非常博学。此前轻视吕蒙的鲁肃说道：“没想到你如今在军事之外如此有学识！你已经不是过去的吴下阿蒙了！”
吕蒙答道：“士别三日，即更刮目相待。”
这个典故衍生出了成语“刮目相看”（亦作“刮目相待”）。它用于表达对他人难以置信的进步或改变的惊叹，意味着应当以新的眼光和更多的尊重来看待此人。