The main idea of ??each paragraph in "Lu Xun's calligraphy tells you what makes a cow"

The first paragraph: deep memory, the second paragraph: talking about "Water Margin", the third paragraph: joking about "hitting the wall", the fourth paragraph: rescuing the coachman, and the fifth paragraph: caring about the maid. Mr. Lu Xun's famous line in "Self-mockery", "A cold brow is pointed at a thousand people, but a bowed head is willing to be a Ru Ziniu" sublimates the meaning of "Ru Ziniu" and is very different from the meaning in the allusion.