It is said that during the period, Liao sent envoys to the Central Plains. Su Dongpo, a bachelor of Hanlin, was ordered to entertain. The envoy of Liao sent a couplet: "Three Lights, the Sun, the Moon and the Stars", and asked Su Dongpo to be the envoy of Liao, thinking that this was absolute. Because the quantifiers in couplets must be corrected by using words. The word "three" is used in the first part, so the second part will not be repeated. There are only three words under "Three Lights", so no matter which number you use, the following words are either more than three or less than three. Who knows, Su Dongpo just thought about it and made a couplet: "Four elegant sentences." Beauty lies in the fact that there are only three names in these four poems: wind, elegance and ode. The original elegance in The Book of Songs can be divided into elegance and elegance. Liao said: "I thought it was absolute. I don't want you to get it easily. " Su Dongpo said: "What is absolute? I can triple it. First: a thunderstorm; Second, the two dynasties were brotherly countries, and third, the four virtues were Henry. " The Liao envoy asked, "The four virtues in the divination of" Gan "in Zhouyi should be Yuan, Heng, Li and Zhen. How did you miss a word? " Su Dongpo replied: "The last word is the imperial edict of the first emperor, and you can't read it casually." It turns out that the first emperor Song Renzong's name is Zhen and Zhen are homophones, which are taboo, so deleting a virtue is also a wonderful work. The above is for reference.