"verve" is also reflected in calligraphy theory. During this period, calligraphy theory's works came out one after another, with extensive contents and pioneering significance. The representative works include: Suo Jing's cursive script, Wei Heng's four-body script, Wei Shuo's "Pen Map", Wang Xizhi's "After Mrs. Wei's Pen Map", "On Calligraphy" and "Twelve Chapters on Pen Map". Exploring its origin, Mrs. Wei and Wang Xizhi's calligraphy theory originated from Cai Yong in the Eastern Han Dynasty. Cai Yong's understanding of the essence of calligraphy art includes three levels, namely, "spirit", "potential" and "form", which can be coordinated and fully expressed in calligraphy works through the efforts of the creative subject. On this basis, Mrs. Wei's "Pen Diagram" clearly puts forward the creative idea of "meaning before writing", which has become a classic language in calligraphy aesthetics and laid a solid foundation for the establishment of the aesthetic status of calligraphy itself.
Wang Xizhi studied under Mrs. Wei, and then transferred to many teachers. After Mrs. Wei, his book theory is the most abundant and has a unique aesthetic character of the times. His book theory is full of a series of aesthetic concepts of calligraphy with artistic dialectics, which has become the origin of the aesthetic concepts of calligraphy in pairs since then. These concepts mainly include: size, depression, urgency, fluctuation, length, density, strength, delay, straightness, hiding, height, distance, Fiona Fang, width, thickness, smoothness, surplus and deficiency, etc. There are two main differences between Wang Xizhi's previous book theory: First, the theory of "showing form and showing potential" puts forward the inseparable relationship between "form" and "potential". The second is the inspiring theory of book meaning, which emphasizes the creative principle of "intention before writing", puts "intention" in the commanding position of the general, and decomposes "intention" into two levels: tangible meaning and intangible meaning.