"Since then, poets have been riding donkeys and wading through mountains and rivers to find the themes of poems and sentences, which are gradually favored by painters. This painting by Xu Wei is the masterpiece of this kind of painting. His characters are often drawn by the method of "reducing the pen", and the composition is simple. They often only draw the foreground, and the foreground is often shot several times, sometimes even completely omitted. There are only a few old people and donkeys in Poems on the Back of Donkeys, which are both in form and spirit. In particular, the description of the donkey is not accurate from the anatomical point of view, but its brisk pace is vividly on the paper. The background branches and vines are messy, which makes people feel bleak in autumn. By using appropriate ellipsis, Xu Wei created an ethereal and meaningful artistic space with profound artistic conception. Painting with calligraphy is another feature of Donkey's Back Poetry. The people, donkeys, trees and vines in the picture contain true, line, grass and official brushwork, which makes people feel that there is an inexhaustible vitality, which is why Xu's paintings are refined and stand out from the crowd. Zhang Dai at the end of Ming Dynasty and the beginning of Qing Dynasty had a pertinent evaluation of Xu Wei's artistic creation of calligraphy and painting: "In the past, people called it rubbings, with pictures in it;" A rubbings with poems in it. Yu is also called the book of the green vine, which contains pictures; There are books in the Ivy Map. "