Yan Ying, a famously upright minister of the Qi State during the Spring and Autumn period, led by example in all matters and lived so frugally that he earned great respect among the people, serving as prime minister under three successive rulers: Duke Ling, Duke Zhuang, and Duke Jing.
One day, as Yan Ying was eating, an envoy arrived from Duke Jing of Qi. Yan Ying divided his own meal into two portions and invited the envoy to join him. As one might expect, neither of them ate their fill.
After the envoy returned, he told Duke Jing of Qi about not being full. Duke Jing was astonished and said,
"I had no idea the Chancellor's household was in such dire straits. How could I have remained unaware all this time? This is my failing."
Duke Jing then sent an envoy to Yan Ying with a thousand taels of gold for entertaining guests. Yan Ying repeatedly declined, and when the envoy arrived a third time, Yan Ying said, "Please tell His Majesty that my household is not poor. My official salary is enough for daily expenses and even to aid the needy. The emperor's treatment is already generous—I cannot accept further gifts."
The messenger, truly at a loss, had to say to Yan Ying, "Prime Minister, I came on the king's orders. If you refuse, I won't be able to report back!" "Then I'll go with you to thank the king in person," Yan Ying replied.
Yan Ying, upon seeing Duke Jing of Qi, spoke first, saying, "Your Majesty's great favor fills me with boundless gratitude. However, a loyal minister should not use the ruler's rewards to give alms to others. I am content to have enough to eat and wear. Please, Your Majesty, do not put me in a difficult position any longer!"
Duke Jing was deeply moved by Yan Ying's humility and integrity, yet he was reluctant to withdraw his decree. "My lord," the Duke said, "consider how Guan Zhong once assisted Duke Huan of Qi in governing the state with such skill that Qi became the first hegemon of the Spring and Autumn period. To honor him, Duke Huan granted Guan Zhong 12,500 households and lands—and Guan Zhong accepted without hesitation. If even Guan Zhong did not refuse a well-earned reward, why must you, Prime Minister, insist on declining?"
Yan Ying still refused to accept, saying sincerely to Duke Jing of Qi, "A sage, after a thousand considerations, is bound to make one mistake; a fool, after a thousand considerations, is bound to have one insight. In this matter of receiving rewards, perhaps Guan Zhong's thinking was not thorough enough, while my view is correct."
Duke Jing of Qi, seeing Yan Ying speak in this manner, had no choice but to drop the matter.
Later, people used the idiom "a thousand plans, one slip" to refer to a self-deprecating remark when stating an opinion.
Source: *Yanzi's Spring and Autumn Annals*, "Miscellaneous Chapters, Part Two"
Meaning of the Idiom: Later, the Chinese idiom "千虑一得" came to describe a self-deprecating remark when stating an opinion.