Line is the most prominent feature of "self-narrative post", which well embodies the "ancient method" of using a pen, round and heavy. In the operation of rounded lines, it is a strong balance between control and strength. Even the thin thread is compact and full, with strong linear density, elasticity and toughness, which reflects its thickness. Thickness is not necessarily thickness, but density.

Self-Narrative Post is a cursive work written by Huai Su, a calligrapher in the Tang Dynasty, in the 11th or 12th year of Tang Dali (776 or 777). It is a kind of paper and ink scroll. Now it is collected in the National Palace Museum in Taipei. The Self-Narrative Post is a brief introduction to Huai Su's life, and also records the poems presented by Yan Zhenqing, Zhang Wei and Dai Shulun. The whole article is full of wild grass, with the pen in the middle, like a conical drawing sand table, which is inclined vertically and horizontally and refuses to accept anything. The whole volume emphasizes that the grass is continuous, turned up and down with a pen, swaying from side to side, fluctuating, sudden and slow, and full of rules, which is the ultimate expression of cursive art.