As early as the early Yuan Dynasty, Bai Juyi showed a tendency to emphasize realism, popularity and irony: "If there is no textual research on today's praise and demotion, there is a lack of punishment and persuasion;" If the poem "The Beauty Sting" does not test politics, then the significance of the make-up test will be abolished. ..... Those who give ci and fu with admonition and irony are wild in nature. "The role of poetry is to punish evil and persuade good, and make up for current politics. The means of poetry is praise, criticism, admonition and satire, so he advocates: "Set up officials to collect poems, make sarcastic remarks, examine their gains and losses, and understand their feelings." (Poetry Sixty-nine) He opposes the simple pursuit of "high palace rhythm" and "strange writing" without content, and even more opposes the gorgeous poetic style of "mocking the wind and making flowers" since Qi and Liang Dynasties. In the preface to new Yuefu, he clearly pointed out that the standard of writing poetry is: "the quality and path of his words are easy to distinguish for those who want to see;" "His words are straightforward and he admonishes those who want to listen; Its business is nuclear and true, so people who use it can send messages; Its body is very smooth and can be played in music songs. " Here, "quality and diameter", "straightness and tangent", "core and reality" and "smoothness and smoothness" respectively emphasize that the language should be simple and popular, the discussion should be straightforward and exposed, the writing should be absolutely false and pure, the form should be smooth and fluent, and it has the color of ballads. In other words, poetry must be authentic, easy to understand and easy to sing in order to be considered the ultimate.
From emphasizing realism, popularity and satire to advocating writing for the monarch and the people, Bai Juyi put forward a systematic theory of poetry, and his satirical poems such as Qin Zhongyin and New Yuefu were created under the guidance of this theory. This theory, with its outstanding realistic pertinence and popularization tendency, may make poetry closer to social reality and even interfere with politics. This theory is a direct inheritance of Confucian traditional poetics and a further development of Du Fu's creation of current affairs. Judging from writing current events, Bai Juyi and Du Fu are the same; But Du Fu only wrote what he saw and felt, and the sufferings of the people were integrated with his own sad feelings. Although he always talks about it in realism, it contains irony, but it is not based on irony. The difference between Du Fu's poems and Bai Juyi's lies in his thought of "being the king", which highlights the practical utilitarian color of poems and leads them to a narrow road. Because of paying too much attention to the ironic function of poetry, poetry is equated with exhortation and commemoration, and the images of many poems are replaced by ironic reasoning and discussion. Due to the narrow and strict evaluation criteria of poetry, a large number of outstanding writers and works that do not meet this standard in history have been excluded. All these have had a certain negative impact on that time and later generations.