She mixed rouge and water to make a small red note with poems engraved on it and gave it to the person she thought fit. At that time, people were proud to get her notes. Later generations simply named it "Xue". This is also the origin of the common "red note" in later poems. Hill once said, "In the depths of this situation, the red notes are colorless." I can't express my deep feelings and touched many people in later generations. Later, the "red note" became an image, especially a letter to a lover. This is what Rong Ruo meant when he said, "Turn on the light to make the book as red as possible".