Wang Xianzhi, the seventh son of the renowned Eastern Jin calligrapher Wang Xizhi, was also a celebrated calligrapher, and the two were known as the "Two Wangs."
Wang Xianzhi was clever as a child. One day at age seven or eight, he watched his father's students playing Chu (an ancient gambling game) at home. Suddenly pointing to one side, he shouted, "Your side is going to lose!"
The students, seeing how young he was yet able to predict the outcome, teased him, "This child is like looking at a leopard through a bamboo tube—he can only see one spot on its hide!"
Actually, the term "looking through a tube" had already appeared before this. Zhuangzi of the Warring States period once said that looking at the sky through a bamboo tube, or pointing at the ground with an iron awl, would make heaven and earth seem small. Cao Cao, the famous statesman and military strategist of the Three Kingdoms period, also used the term "looking through a tube."
Cao Cao placed great importance on talent. In his hiring standards, he opposed the traditional notion of prioritizing family status and instead championed "appointing only the worthy." At the time, the aristocratic leader Kong Rong opposed and attacked Cao Cao for this. In response, Cao Cao issued a special decree, "On the Conduct and Ability of Officials," denouncing Kong Rong and his ilk for speaking very one-sidedly, like looking at a tiger through a bamboo tube—seeing only a tiny part, never the whole.
Later, people used the idiom "Looking at a Leopard Through a Tube" to describe seeing only a part rather than the whole. It is often used together with "Catching a Glimpse of a Spot," meaning one can infer the whole from what is observed.
Source: *A New Account of the Tales of the World*, Chapter "Upright and Correct"
Meaning of the Idiom: Later, the Chinese idiom "管中窥豹" came to describe how seeing only a part rather than the whole.