Lü Meng, styled Ziming, was a famed general of the Wu Kingdom during the Three Kingdoms period. Born into poverty, he had little schooling as a child, and even after joining the army and leading troops, he rarely picked up a book. His lack of education often drew scorn from high-ranking officials.
Sun Quan, the King of Wu, once advised Lü Meng to study diligently. But Lü Meng replied, "There are too many matters in the army; I'm busy every day and have no time for reading."
"Am I asking you to master the classics and become an erudite? But you must have general knowledge! You say you're busy—how does that compare to me? Why can't you just find time to study on your own?" Sun Quan said.
Sun Quan then shared the benefits of his own reading, citing Emperor Guangwu of Han, who never stopped learning even amid military chaos and was always seen with a book in hand, and Cao Cao, who famously declared himself an eager learner even in old age, to inspire Lü Meng.
Moved by Sun Quan's words, Lü Meng devoted himself to reading with tireless diligence, soon surpassing even learned scholars in knowledge. Later, when Lu Su passed by Lü Meng's camp on his way to guard Lukou—having previously dismissed Lü Meng as uneducated—he visited out of courtesy. Lü Meng warmly received him and asked, "You'll be stationed near the Shu general Guan Yu. How do you plan to both cooperate with him and stay vigilant?" Lu Su shrugged casually, "I haven't thought about it; I'll decide when the time comes." Lü Meng sternly rebuked him, "You must not underestimate the enemy!" He then presented five strategies for Lu Su's review. Stunned, Lu Su patted Lü Meng's back and said warmly, "I always thought you were all brawn and no brains. Now I see your vast learning—you are no longer the uneducated brute you once were!"
Lü Meng laughed, "After three days apart, one should look at each other with new eyes!"
From that day on, Lu Su and Lü Meng became close friends, and when Lu Su was on his deathbed, he even recommended Lü Meng to succeed him as Grand Commander!
Later, the idiom "Gua Mu Xiang Dai" came to mean seeing someone in a new light, or treating them with special regard.
Source: *Records of the Three Kingdoms*, "Biography of Lü Meng"
Meaning of the Idiom: Later, the Chinese idiom "刮目相待" came to describe how seeing someone in a new light, or treating them with special regard.