The allusion comes from: Introduction to Dou E's Unjust Life: Scholar Dou was unable to repay Cai Po's usury and gave his seven-year-old daughter as a child bride to pay off her debts. When Dou E grew up, she married Cai Po's son. After two years of marriage, Cai Po died of illness. Later, Cai Po asked Dr. Sailu for debts. Dr. Sailu tricked her into killing people in the suburbs and was caught by the rogue Zhang Lver and his son. After Dr. Sailu left in shock, Zhang Lver and his son forced Cai Po and Dou E to adopt their father and son, which was resolutely resisted by Dou E. In order to get married, Zhang Lver tried to poison Cai Po. Cai Po is ill and wants to eat mutton soup. Zhang poured the poisonous donkey into the mutton soup. Cai Po vomited and poisoned Zhang Donkey's old man. Zhang Lver sued the government in the name of "poisoning his father-in-law", and Geng Tao, a corrupt official, persecuted and beheaded Dou E. Later, Dou was admitted to Jinshi, and went to visit the government and visited the officials. Dou E's ghost complained to her father, and Dou found out the truth and took revenge. There are often discounts for "cutting moths" on the stage.