What is the origin of Xi?

When Wang Anshi, a politician, writer and thinker in the Northern Song Dynasty, went to Beijing to take the exam at the age of 23, he passed Majia Town and saw a sign on the lantern of Mr. Ma's house: "Run the lantern, run the lantern, stop the lantern." After reading it, I can't help clapping my hands and praising: "What a pair of couplets."

The next day, Wang Anshi was full of literary thoughts in the examination room. Examiner Ouyang Xiu saw that he was clever, so he pointed to the flying tiger flag in front of the court to test him: "Flying tiger flag, flying tiger flag, flag rolling and hiding." Hearing this, Wang Anshi casually said, "If you run the light, the light will run away and the light will stop." Ouyang Xiu praised again and again after listening to it.

Wang Anshi returned to Majia Town after the exam, thinking of the help of lanterns, strolled to Mr. Ma's house. Mr. Ma asked him to put the lantern on, and Wang Anshi replied without thinking: "Flying Tiger Flag, Flying Tiger Flag, Flag Rolling and Hiding." Seeing his outstanding talent, Mr. Ma betrothed his daughter to him and married him in Mafu on an auspicious day. Just as the couple were worshipping heaven and earth, there was news that Wang Anshi was appointed as the fourth Jinshi. The Majia compound was suddenly filled with jubilation, firecrackers were everywhere, and gongs and drums were loud.

Du Fu's poem "Four Happiness Poems" says: After a long drought, you will meet the rain, and you will meet an old friend in another country; Wedding night, for the first time. One day, both the horse and the king were very happy. At this time, Wang Anshi couldn't help but grab a pen and write a big book on red paper to celebrate his family. The maids took it and posted it everywhere. This is the origin of posting big red double happiness words everywhere when holding a happy event.