Read the pinyin of "four" four times, and "four" means a synonym for "sacrifice". In ancient times, sacrifices and battles were wars, and Guan Chan was an important event for ancient kings. In ancient times, etiquette was more important than anything else. Respect for young people and old people is very important, so there is an ancient etiquette here. That is, the ritual of sacrifice. If you meet a word you don't understand, look it up in the dictionary. Of course I can see that you are a studious person. I hope you can keep such a positive attitude.