It is said that Lu Ban was the wisest and most skillful craftsman in ancient China. His original name was Gongshu Ban, but because he was from the State of Lu during the late Spring and Autumn period, "Lu Ban" became the name by which later generations came to know him.
Once, he arrived in the city of Gusu in the State of Wu. This "paradise on earth" truly lived up to its reputation. Ancient city towers stood in orderly succession, and teahouses and taverns bustled with activity. Lu Ban's interest in sightseeing grew, and he became absorbed in studying the characteristics of Suzhou's architecture, delighting in the surroundings.
Suddenly, a loud, noisy commotion reached his ears. Following the sound, Lu Ban saw ahead on a lush green open field a newly built pagoda towering high. A crowd surrounded the pagoda, shouting and arguing, but it was unclear what they were doing.
He slowly walked over and pushed through the onlookers. He saw an elderly man dressed in silk, wearing a tall hat and a fragrant pouch at his waist, visibly furious—his veins bulging, eyes wide and glaring, radiating anger like a bull charging at the stars. Facing him, a middle-aged man crouched on the ground, head in hands, looking utterly dejected.
Lu Ban was deeply puzzled. Upon inquiring, he learned the full story.
The elderly man was a well-known local tycoon who, in an effort to accumulate virtue and do good deeds, had commissioned the construction of this pagoda to leave a legacy for generations to come.
The project had been contracted to this very craftsman. After nearly three years of hard labor—transporting timber, erecting the structure, and meticulous planning—the pagoda was finally completed. Yet, for some unknown reason, no matter whether viewed horizontally or vertically, the pagoda was clearly leaning.
Measurements confirmed the pagoda was indeed tilted by nearly ten degrees. People shook their heads and pointed, gossiping among themselves. The tycoon was furious, believing that building the pagoda had instead brought criticism, damaging his efforts to achieve spiritual merit. He confronted the craftsman directly: either demolish and rebuild it, or straighten the pagoda; otherwise, he would hand him over to the authorities for severe punishment.
This put the craftsman in a terrible predicament. If he had to demolish and rebuild, even selling his children and family possessions wouldn't cover the financial burden. And straightening the pagoda was impossible too—though wooden, the pagoda still weighed nearly a million catties (approx. 500,000 kg). He could only sigh helplessly, staring at the pagoda.
Lu Ban carefully inspected the pagoda, walking around it, then looked at the helpless craftsman. He walked over and comforted him: "Don't worry. Just bring me some timber, and I alone can straighten it in less than a month!"
The craftsman, half-believing and half-doubting, had no other options. So he carried in the timber and waited with a glimmer of hope. Lu Ban, however, refused any help. He chopped the timber into many small, wedge-shaped pieces with sloped surfaces, then began hammering them one by one into the side of the pagoda where it was leaning, gradually lifting the slanted side. With the sound of constant hammering, working from dawn to dusk for a month, the pagoda indeed stood upright once more.
Overwhelmed with gratitude, the craftsman asked Lu Ban: "Master, why does this method of correction make the pagoda stand straight?"
Lu Ban replied: "Because the leaning pagoda is made of wood and uses a 'chuan-dou' structural system, where the components are tightly interlocked, forming a cohesive whole. Thus, we can straighten it by driving in wooden wedges. These wedges have a sloped surface, making them easy to drive in, and they possess the effect of 'using four ounces to move a thousand catties.' Once driven in, they lift the height of the pagoda's tilted side, so the pagoda no longer leans."