A Madman's Diary was a famous novel by Lu Xun. "Diary of a Madman" tells us that feudal autocracy is essentially to oppress and exploit people in terms of economy, to shackle and suppress people in terms of spirit, and to fundamentally destroy people's hope of survival. A Madman's Diary was "intended to expose the evils of the family system and ethics." Through the image of a persecutor, with the protagonist's crazy thinking, confused language, and confused eyes, he revealed and pointed out the essence of the old etiquette. "I opened the history book and checked it. There was no age in this history book. On every page, the words 'benevolence, righteousness, morality' were written. I couldn't sleep, so I read it carefully for half a night. Only then did I see the words in the gaps. The whole book was written with the word 'cannibalism!' "This passage is obviously not the ravings of a mentally ill person, but a profound revelation of the essence of feudal ethics.