Why did Song Poetry emphasize "rational interest"?

The so-called rational interest refers to the philosophy of life embodied in poetic images. The cultural root of the formation of interest in reason in Song poetry is not mainly Neo-Confucianism, but the Zen machine of Buddhism. The most interesting representative works in Song Dynasty were mostly written by Wang Anshi, Su Shi and their followers Huang Tingjian and Chen Shidao, whose philosophical thoughts had formed their own system before the formation of Neo-Confucianism. For example, Su Shi's "Two Rhymes, Giving Old Poems": "If spring comes, there will be no return to the flood unless you follow the old path. I hope the teacher is really like a bright moon, and no one will meet in the urn. " That is, it originated from the ode to the vinegar-headed monk fighting machine front contained in the biography of the eminent monk.