This literary term is used in poetry to comment on a ruler’s moral character, policies, decrees, and performance, either in praise or criticism. Confucius（551-479BC） was the first to point out that poetry could be used to vent resentment and thus established a basic function of poetry writing by emphasizing the role The Book of Songs played in voicing grievances. In the Han Dynasty, however, poetry tended to be used as a vehicle for extolling the accomplishments and virtues of rulers. In “Introductions to Mao’s Version of The Book of Songs” and Zheng Xuan's （127-200）“Preface to On the Categories of The Book of Songs,” two influential writings on theory of poetry published during the Han Dynasty, extolment and satirical criticism was regarded as an underlying principle of poetic criticism. This principle was widely employed by poets and writers of later generations as a way of getting involved in politics and making their impact on the society. This constituted a fundamental function and an essential feature of Chinese literature.

Poems are composed to applaud the rulers to continue to do what is good by extolling their achievements and virtues, and to urge them to change the erroneous course by satirizing and criticizing their wrong doings. (Zheng Xuan: Preface to On the Categories of The Book of Songs)

To Confucian scholars in the Han Dynasty, poetry has two basic functions: extolment and satirical criticism. (Cheng Tingzuo: Qingxi Collection)