How to explain the theory of offering poems

Ancient viewpoints on the source of the works of The Book of Songs. Judging from the pre-Qin ancient books such as Guoyu and Zuo Zhuan, The Book of Songs mainly comes from the poems offered by officials and scholars, who satirize or praise them by offering poems. It is generally believed that many poems in The Book of Songs, such as Elegance, Xiaoya and National Style, may have been collected by offering poems.