During the Song Dynasty, a man named Zhang Guaiya served as the county magistrate of Chongyang County. At that time, the area was plagued by rampant theft, with even the government treasury frequently losing money and goods. Determined to curb this corruption, Zhang Guaiya seized an opportunity when a minor clerk was caught sneaking out with just one coin hidden in his hat. The magistrate ordered the clerk flogged, but the clerk protested, "I only stole a single coin—why punish me so harshly?" Zhang Guaiya replied, "If you steal a coin today, tomorrow you'll steal a thousand. A small drip can soak through a whole garment." He then beheaded the clerk to make an example, and from then on, theft in the county ceased entirely. This story gave rise to the idiom "a single coin, a thousand li," illustrating how minor offenses, left unchecked, can lead to major crimes.
One day, he finally found an opportunity. That day, while patrolling around the government office, he suddenly saw a minor official in charge of the county treasury rushing out of the vault in a panic. Zhang Guaiya quickly called out to stop him, asking, "Hey! Why are you in such a hurry?"
“Nothing.” The treasury clerk replied.
Zhang Guaiya, suspecting the treasury keeper of theft after noticing frequent losses, ordered a search and found a single copper coin hidden in the keeper's headscarf.
Zhang Guaiya escorted the treasury clerk back to the main hall for interrogation, asking how much money he had stolen from the vault. The clerk refused to admit to any additional theft, so Zhang ordered him beaten. The clerk protested angrily, shouting, "What's so serious about stealing a single copper coin? You beat me for this? You can only hit me—can you actually kill me?"
Zhang Guaiya, seeing the treasury clerk dare to defy him so openly, was greatly enraged. Without hesitation, he took up his vermilion brush and pronounced: "One coin a day, a thousand coins in a thousand days. A rope can saw through wood, and water can wear through stone."
The saying means that stealing one coin a day adds up to a thousand coins over a thousand days; just as a rope constantly sawing through wood will eventually cut it, and dripping water can wear through stone.
After the verdict was delivered, Zhang Guaiya ordered the guards to escort the treasury clerk to the execution grounds for beheading as a public warning.
From then on, the theft problem in Chongyang County was curbed, and the overall social atmosphere improved significantly.
Later, the idiom "dripping water wears through stone" came to symbolize persistent effort, where even small forces can achieve great feats.
Source: Luo Dajing (Song Dynasty), *Crane Grove Jade Dew*
Meaning of the Idiom: Later, the Chinese idiom "滴水穿石" came to describe persistent effort, where even small forces can achieve great feats.