How to write the general beginning of An Introduction to China's Ancient Poems?

In ancient times, when information technology was underdeveloped, it was very inconvenient for people to transmit information from one area to another, so they compiled the written poems into songs and the poems came from people's mouths. Poetry originated from ancient social life, which is a rhythmic and emotional language form due to labor production, sex and primitive religion. "Shangshu Yu Shu" records: "Poetry expresses ambition, song expresses Tao, sound is eternal, law and harmony." "Book of Rites and Music" records: "Poetry expresses ambition; Song, chanting its voice; Dance, move its capacity; The three are based on the heart, and then the instrument follows it. " In the early days, poetry, song, music and dance were integrated. Poetry is the lyrics. In actual performances, it is always sung with music and dance. Later, poetry, song, music and dance developed independently and became independent adults. Distinguish songs from poems by entering music or not. Music is a song, but poetry is not. Poetry is a kind of language art, which is differentiated from songs, and songs are a kind of music literature with a long history. The Book of Songs is sung with music. Technically, it is a song. Because of this, The Book of Songs is regarded by scholars as a symbol of the maturity of China's music literature.