When talking about how to take reading notes, he summed up the following three words according to his decades of academic experience:
One is "small". That is, write it down in a small book. Xia Lao's reading notes are small notebooks, one for each event, which is convenient for sorting. He named his notes "Lu Lu badminton Lu" ("Holding them in both hands; Lu: Blister). Because Zhang Xuecheng, a scholar in Qing Dynasty, once talked about the importance of taking notes when reading, saying that reading without taking notes is like rain falling into the sea without a trace. The word "Lu Lu badminton" has its own meaning.
The second is "less". "Less" means to remember carefully and write down every item with the least number of words. But remember to be diligent and write more articles. You can write many articles on each question. An isolated piece of knowledge is invisible, and many pieces together will deepen the understanding of a certain knowledge. In this way, every time you read something, you will gain something and gradually enrich your knowledge.
The third is "le". "Le" means to have a thorough understanding of what is said. Write down one. Think carefully and chew carefully before writing. The combination of pen and brain makes what you have learned become "fermented" knowledge in your own mind.