This refers to a literary style that appears plain and dry, mild and moderate. Here, dry and plain does not mean insipid, dull, common or shallow; rather, it suggests a means of expression that, while appearing prosaic, is rich in substance within. Its aim is to convey, in plain and simple language, a message that is not lacking in breadth or profundity and to create a deep and subtle, rich and far-reaching effect. In the early years of the Northern Song Dynasty, an ornate and sumptuous style prevailed in literature. Men of letters such as Mei Yaochen and Ouyang Xiu argued for literary renewal and endorsed a plain and penetrating style. They held that the essence of poetry lies in authenticity and true feeling and that there was no need to be too rhetorical. With the classical examples of Tao Yuanming’s and Liu Zongyuan’s poetry in mind, Su Shi went on to put forth the notion of “dry plainness.” It comes close in meaning to “calm,” “unassuming,” or “unpretentious” – a convergence of the peaceful and profound beauty of Daoism and the elegant beauty of Confucianism.
I value the style of dry plainness because it looks withered and dry outside but is rich inside; it appears plain but is in fact beautiful. Poetry by such writers as Tao Yuanming and Liu Zongyuan is like this. If inner and outer were equally dry, why praise it? (Su Shi: A Critique of Poems by Han Yu and Liu Zongyuan)
Therefore, what seems most plain in the world is in fact the most resplendent, and what seems most dry and withered is in fact the most fruitful. Poems by people like Tao Yuanming and his followers read naturally; they more or less achieved this artistic effect, though not completely! (Bao Hui: Reply to Fu Dangke’s Discussion of Poetry)