Yan Ying, also known as Yanzi, was a quick-witted and highly talented diplomat and statesman from the State of Qi during the Spring and Autumn Period.
Once, the King of Chu heard that Yanzi was about to visit Chu and said to his attendants, "Yan Ying is a skilled speaker from Qi. I want to take this chance to humiliate him. Any ideas?"
The attendants replied, "When he arrives, please allow us to bind a man and lead him past you. You ask, 'What is this man doing?' We answer, 'He is a man of Qi.' You then ask, 'What crime has he committed?' We say, 'He committed theft.'" The King of Chu nodded in approval.
Yanzi arrived in the state of Chu, and the King of Chu hosted a banquet in his honor. In the midst of the revelry, two officials dragged a bound prisoner past the king. The king feigned surprise, stood up, and asked, "What is this bound man guilty of?" The officials reported, "He is a man of Qi, guilty of theft."
"Oh, a man from Qi." The King of Chu slowly turned around and said sarcastically to Yanzi, "Are all you people from Qi accustomed to stealing?"
Yanzi abruptly stood up and replied solemnly, "I have heard of this: an orange tree grown south of the Yangtze River yields sweet oranges, but transplanted north of the Huai River, it becomes bitter trifoliate fruit. Though their leaves resemble each other, the taste is entirely different. Why? Because the soil and water are different. Now, this man was no thief in Qi, yet in Chu he steals—could it be that Chu's soil and water have transformed him into this?"
King of Chu remained silent, then smiled bitterly and said, "A sage cannot be joked with; I have only brought embarrassment upon myself." From this story, people derived the idiom "An orange becomes a trifoliate orange," which illustrates that objective environment and conditions have an undeniable influence on people and things.
Source: *Yanzi's Spring and Autumn Annals*, "Miscellaneous Chapters, Part Two"
Meaning of the Idiom: Later, the Chinese idiom "桔化为枳" came to describe how objective environment and conditions have an undeniable influence on people and things.