As for the function of poetry, Shangshu first put forward the viewpoint that "poetry expresses ambition, song always speaks, sound is eternal, and law is harmonious". On this basis, Mao's Preface further explained: "A poet, with aspirations in his heart, speaks as a poem."
In short, the so-called "poetry expresses ambition" is to require poetry to play the practical functions of "filial piety between husband and wife, respect each other as guests, and change the customs of the United States."
This theory originated in the pre-Qin period, and gradually evolved into the mainstream poetic theory in the society at that time through the processing of Preface to Mao Poetry and the elaboration of Confucianism. This poetic concept represented by functionality has influenced China's literary development for hundreds of years.
The proposal of "poetry based on emotion" really impacted the theory of "poetry expressing ambition", so that later scholars often put the two in opposition. Scholars in the Qing Dynasty thought that "knowing without knowing the etiquette and righteousness, in other words, being insipid from Lu makes people go astray", that is, criticizing Lu Ji's theory of "poetic sentiment" made poetry go astray.
In fact, this criticism is inaccurate. First of all, we must understand what "poetry" is. Starting from the Buddhist explanation of karma, Mr. Liu Yunhao thinks that karma is just a little bit of karma, and the so-called "poetry is born of emotion-emotion, emotion is born of external environment-feeling of things".
In other words, poetry originates from the poet's true feelings arising from the changes of things outside his heart.
Therefore, "poetic sentiment" emphasizes that poetry originates from the poet's subjective temperament, and its theoretical focus is to explain the achievements of poetry rather than its functions. In fact, Lu Ji also expressed the meaning of "determined to win" in his prose, saying that "staying in the central area is mysterious and taking care of the grave". According to Kong Anguo's explanation, the "grave" here mainly refers to the Confucian way.