Han Xin, a great general who helped Emperor Gaozu establish the Han dynasty, was in dire straits before he achieved fame. At that time, he often fished by the city moat, hoping to catch something to alleviate his hunger. However, this was not a reliable method, and he often went hungry.

Fortunately, in the area where he often fished, there were many washerwomen (women who washed silk floss or old clothes) working by the river. One of them, feeling great sympathy for Han Xin's plight, continuously offered him food. Han Xin was deeply grateful for the kindness shown by this hardworking washerwoman, who herself barely made ends meet with her own hands. He told her that he would surely repay her generously in the future. The washerwoman was displeased by his words, indicating that she did not expect any repayment from Han Xin.

Later, Han Xin rendered many meritorious services to the King of Han and was enfeoffed as the King of Qi. Remembering the kindness he had received from the washerwoman in the past, he ordered his attendants to send her food and wine, and also sent her a thousand taels of gold as a token of his gratitude.

This idiom originates from this story. It means that one should never forget kindness received, no matter how small the favor may seem. During times of difficulty, even a little help is precious. When one becomes capable, it is only right to generously repay the benefactor.

When using this idiom, it is crucial to understand its full meaning: firstly, genuinely kind people who love to help others never expect repayment; secondly, a wealthy person's charity to the poor is a donation and cannot be called 'a meal worth a thousand pieces of gold' even if the recipient later becomes successful and repays them; thirdly, the most valuable form of help is extended out of friendship and sympathy when one is also in difficult circumstances. Such help, in the eyes of the recipient, truly makes 'one meal' worth 'a thousand pieces of gold'.