Full of thick ink, writing slowly, often can not form a dry pen and flying white. With the decrease of ink in the pen and the increase of pen speed, dry pen and flying white will gradually appear. However, dry writing should be a natural thing and must not be pursued deliberately. All good calligraphy works should be the emotional expression of the author on the basis of skillful techniques. It is said that Preface to Lanting was written by Wang Xizhi when he was slightly drunk. After waking up, he can no longer write the charm he wrote when he was not drunk. Yan Zhenqing's "Sacrifice to a Nephew" is praised by later generations as the second running script in the world, comparable to Wang Xizhi's "Preface to the Lanting Pavilion". It can get such a high evaluation, that is, although there are so many smears and sketches, the pen and ink are dry. But it was Yan Zhenqing's grief and indignation, which was expressed in his works in one go, so he was more frank.