Lü Meng was a general of the state of Wu during the Three Kingdoms Period (220-180). Born in a poor family, he did not have the chance to go to school when he was a child. When he was grown, he joined the army, and there was even less time for reading.
Once, the king of Wu summoned Lü and said to him, "You're a big general now. You'd better read some books to widen your horizons."
"I am so busy with military work," Lü replied. "I'm afraid I have little time to read."
"Are you busier than I am?" the king said. "Even I find time to read books on the art of war, and they've benefited me greatly. Read more about the experience of our predecessors. You'll make greater progress."
Accepting the king's advice, Lü set about reading history and military writings. One day, chief commander Lu Su visited Lü Meng. Lu Su had looked down on Lü Meng in the past. He was surprised to find Lü had become so knowledgeable.
"I thought you only knew how to fight!" Lu Su said. "You are not the Lü Meng you used to be."
"You should always look at a person with fresh eyes – even if you've only been apart three days," Lü Meng replied.
Lü Meng's remarks inspired the idiom "guā mù xiāng kàn", or "guā mù xiāng dài". It's used to express astonishment by others' fabulous progress or improvement and increased respect for him or her.
guā mù xiāng kàn
dà zhì ruò yú
a man of great wisdom often appears slow-witted