During the Tang Dynasty, a local official, wishing to express his deep respect for the emperor, dispatched a man named Mian Bogao to present a swan as tribute.

Mian Bogao journeyed through mountains and rivers. As he was bathing the swan by Mianyang Lake, the swan unexpectedly escaped, leaving him with only a single feather.

With nothing else to present, Mian Bogao felt he had no choice but to write a poem explaining the situation: 'To His Majesty, the Emperor of Tang, I humbly request your leniency for Mian Bogao. Though the gift is light, the sentiment is profound, a thousand li journey to deliver but a goose feather.'

Upon receiving the message, the emperor was not angered. Instead, he understood Mian Bogao's sincerity and rewarded him, appreciating the profound sentiment behind the humble offering.