Folk songs were very popular during the Spring and Autumn Period and the Warring States Period. "Zuo Zhuan", "Guoyu" and Zhuzishu often quoted folk songs. Due to the popularity and development of ballads, poetry in the Warring States Period had new achievements in content and form. At this time, the development of poetry was just like the development of prose, first reflected in the change of style. In the Book of Songs, a collection of poems before the Spring and Autumn Period, "Ya" and "Song" are aristocratic literature, while "Guofeng" is folk literature. The presence or absence of the word "xi" was one of the criteria for distinguishing aristocratic literature from folk literature at that time. It is common to use "xi" as a particle in "Guofeng", but rarely in "Daya", "Xiaoya", "Song of Zhou", "Song of Lu" and "Song of Shang". It turns out that the ancient pronunciation of the word "xi" is "ah", which is a commonly used particle in ancient folk songs. By the Spring and Autumn Period and the Warring States Period, folk songs had lively and lively lyrics with varying syntax, unlike "Guofeng" which often used neat four-character sentences. At this time, folk songs were often accompanied by music. In the musical accompaniment, singing lyrics of varying lengths and liveliness was very touching. When Jing Ke set out from the State of Yan to Qin to assassinate the King of Qin, he passed by Yishui. Gao Jianli was playing a stringed bamboo instrument called Zhu. Jingke sang: The wind is rustling, the Yishui is cold, and the strong men will never return once they are gone. The tunes of Jing Ke's song and Zhu played by Gao Jianli are consistent. It is said that first it was the "sound of change" ("Bian Zheng" is a sad tone), and everyone shed tears after listening to it; When everyone heard this, their eyes widened and their hair seemed to stand on end ("Warring States Policy·Yan Ce III"). At this time, the folk songs of the south became even more varied and melodious. It is said that when Confucius traveled south to Chu, he heard a song sung by a child: The water in Canglang is clear, and I can wash my tassel; the water in Canglang is turbid, and I can wash my feet. ("Mencius·Li Lou Chapter 2") It is said that during the reign of King Qingxiang of Chu, Hubei Junzi was rafting in Xinbo. As soon as the sound of the bells and drums stopped, the Yue people who paddled the oar started singing at the same time. They sang a song with thirty-two syllables in Vietnamese. Because Ejun couldn't understand it, he asked someone to translate it in Chu language. It became such a poem of Chu: Today and evening, I am coming, and I am flowing in the middle of the island. What day will it be that I shall be in the same boat with the prince? Being humiliated and treated well is not shameful. My heart is stubborn and unstoppable, I learned about the prince. There are trees in the mountains, and the trees have branches. My heart is happy for you, but you don’t know it. ("Shuo Yuan Shan Shuo Pian") Due to the development of poetry, southern thinkers used poetry to clarify philosophy. "Laozi" has five thousand words, most of which are written in rhyme. The language is concise and vivid, and the meaning is profound. For example, it praises those who are good at practicing the "Tao": Those who were good at practicing the Tao in ancient times were subtle and mysterious, and could not be discerned. I can't recognize it, so I made it look like: Yu is like wading through the river in winter, still is like being afraid of the neighbors, as if it is a guest, Huanxi is as if the ice is about to be released, Dunxi is as simple, open as if it is a valley, mixed It looks like turbidity. Who can stop the turbidity and make the stillness clear? Who can be peaceful for a long time and live in peace? Those who protect this way do not want to be full, but they are not full, so they can hide it and not create new things.
(Chapter 15 of "Laozi")