During the Spring and Autumn period, the states of Zheng and Qi were on excellent terms. Duke Xi of Qi had a young daughter named Wen Jiang, who had reached marriageable age. The duke decided to betroth her to Crown Prince Ji Hu of Zheng.
Duke Xi of Qi sent an envoy to the State of Zheng to propose a marriage. Duke Zhuang of Zheng, delighted by the envoy's purpose, hosted a banquet for the Qi envoy while summoning Crown Prince Ji Hu and informing him of the matter. Ji Hu thought for a moment and said, "Father, I cannot agree to this marriage."
A courtier quietly advised him, "Qi is a great state. If you marry the daughter of the Qi ruler, you will have a powerful ally in the future. It would be best for the crown prince to agree."
The envoy from Qi was displeased and asked Ji Hu why he had rejected the marriage. Ji Hu replied, "Everyone should have a suitable spouse. Qi is a great state, while our Zheng is a small one. This is like one being rich and the other poor. A poor man's son cannot aspire to marry a rich man's daughter."
The Qi envoy, finding Ji Hu's reasoning sound, had nothing more to say and returned to report to Duke Xi of Qi, putting the marriage arrangement on hold.
Soon after, the State of Qi was invaded by the northern Shanrong tribe. Duke Xi of Qi requested reinforcements from Duke Zhuang of Zheng, who dispatched Ji Hu to lead the rescue. Ji Hu fought with exceptional bravery, and his troops were highly skilled in battle, swiftly repelling the Shanrong invasion.
After the battle, Duke Xi of Qi, impressed by Ji Hu's valor, grew even fonder of him and sent matchmakers to Zheng again. But Ji Hu refused once more, saying, "I rejected this marriage before to avoid relying on a powerful state. I believe one must win their own happiness. Now that I've helped Qi defeat the Shanrong, if I accept this match, the people of Zheng will say I used war to secure a wife. I cannot agree."
Seeing Duke Zhuang of Zheng's firm refusal, the duke sent a messenger to Duke Xi of Qi to politely decline the marriage alliance.
Duke Xi of Qi, at his wit's end, soon married Wen Jiang off to Duke Huan of Lu.
Later, the idiom "Qi Is Too Great to Match" was used by those declining marriage proposals to express that their own status or position was too low to presume a match.
Source: *Zuo Zhuan*, Chapter "Duke Huan's Sixth Year"
Meaning of the Idiom: Later, the Chinese idiom "齐大非偶" came to describe how their own status or position was too low to presume a match.