During the Northern Song Dynasty, Wu Shi, the magistrate of Zheng County in Huazhou (modern Huaxian, Shaanxi), was known for his vast knowledge and flexible governance, always keeping the people's welfare in mind.
Once, an official decree arrived from the imperial court, ordering Huazhou to transport 50,000 hu of rice to Chang'an, with Zheng County responsible for 30,000 hu.
Wu Shi believed that with the manpower situation in Zheng County, it was impossible to accomplish, so he proposed to his superiors the suggestion of "moving troops to where food is available"—that is, relocating troops to Huazhou for local supply, which saved a great deal of manpower and resources, reduced the burden on the people, and did a good deed for them.
During the reign of Emperor Huizong of the Song Dynasty, the emperor called for policy suggestions from across the empire. When officials from remote regions submitted memorials that did not follow the proper writing format, some bureaucrats wanted to reject them outright. However, the imperial advisor Wu Shi stepped forward and argued, "The true value of a memorial lies in the substance of its advice, not in the strict adherence to form. We should judge by content, not by format." The court accepted his counsel, ensuring that many valuable proposals were heard and considered.
On another occasion, a scholar in Huazhou offended a local official with his writing, and the schoolmaster threatened to report him, putting the student at risk of legal trouble.
When Wu Shi learned of this, he took that essay and threw it into the furnace to burn, saying to the academic official, "Since a subject cannot bear to hear such words, how could he bear to let the sovereign hear them?"
The student was finally saved, and the school official felt the problem had been resolved.
During the Three Kingdoms period, Wu's approach to problems was so flexible and decisive that it was closely tied to his quick wit. His speed in writing was even more astonishing—he never needed a draft, completing his work in one swift stroke.
Therefore, when Wu Shi later served as an official in the capital, people at the Imperial Academy and National University called him a "Walking Bookcase," praising his vast and encyclopedic knowledge. Later, people used the idiom "Walking Bookcase" to describe someone who reads widely and is highly learned.
Source: *History of Song*, "Biography of Wu Shi"
Meaning of the Idiom: Later, the Chinese idiom "立地书橱" came to describe how someone who reads widely and is highly learned.