Supplementary information: Ancient songs, myths and legends are recorded in ancient books. It is said that it is a "wax word" that appeared in the Shennong era: "Earth, against its home! Water belongs to its valley! Insect, don't do it Herbs, return to it! " This is a song about farming sacrifice. As for Song of Breaking the Earth, Song of Resistance to Deflection, Song of Qingyun, Song of Yaojie, Song of Liao and Song of Nanfeng, etc. It is said that it was in the Yao and Shun period, and its ideological content and words were obviously false promises of later generations. But there are some simple rhymes, which may be the legacy of the original song. For example, "Wu Yue Chun Qiu" Volume 9 "Playing Songs" said: "Break bamboo, continue bamboo, fly soil, kill one by one. The word "ancient meat" reflects the process of primitive people making slingshots and hunting. The language is simple but rhythmic. Obviously, this is a very old ballad. The song "Waiting for People" sung by Tu Shanshi's daughter in Lu's Spring and Autumn Annals, although only one sentence, is a more credible summer poem we see today.