Briefly describe the purpose of the ruling class to collect poems.

The purpose of the ruling class's poetry collection is not only to educate and entertain their children, but also to understand the people's reaction and investigate its political effect, so as to further consolidate its rule. The so-called "you are so concerned about customs, know the gains and losses, introspect and correct yourself" ("Hanshu? Art and literature "). It is for this purpose that The Book of Songs created an excellent realistic tradition of China literature ~