Jiushi 九勢

Jiushi 九勢 "The nine momenta" and Bilun 筆論 "On the brush" are two essays on calligraphy written during the late Eastern Han period 東漢 (25-220 CE) by Cai Yong 蔡邕 (132-192 CE). He is not only known as the chief calligrapher of the Stone-Classics project Xiping shijing 熹平石經 , but also as the inventor of the writing mode "flying white" (feibai 飛白), a technique producing blank spaces within brush strokes by not focusing the tip of the brush but allowing hairs to stand off. Cai is also the author of the essay Lishu shi 隸書勢 "The momenta of chancery script", which is a critique of the widespread use of the "grass script" (caoshu 草書), and the two praise poems Dazhuan zan 大篆贊, and Xiaozhuan zan 小篆贊, both glorifying the old seal script.

Bilun discusses the mental mood of a calligrapher doing her/his work. It explains the character for "writing" or "calligraphy" (shu 書) from the viewpoint of a writer or artist, and is thus a testimony of the emergence of calligraphy as a field of the arts.

The essay Jiushi, also called Jiushi bazi jue 九勢八字訣, explains nine methods of using the brush when doing calligraphy, particularly during the use of the contemporary writing style of the chancery script (lishu 隸書). Cai holds that the shape given to characters was an expression of nature through the writer and his/her brush. If "naturalness" (ziran 自然) was guaranteed, the forces or energies Yin and Yang would emerge. These two would in turn generate the shape of written words. The force of hand and brush was visible in the centre of a character, even if the "momentum" (shi 勢) was unrestrained in all the parts of the word. While the upper parts of a character covered the lower ones, the latter would lift and support the upper ones in a symmetric way. This "extraordinary" (qiguai 奇怪) momentum was transferred by soft brushes.

The brief text is quoted in Zhang Yanyuan's 張彥遠 (early 8th cent.) Fashu yaolu 法書要錄 and Chen Si's 陳思 (1225-1264) Shuyuan jinghua 書苑菁華, and in the collection Lidai shufa lunwen xuan 歷代書法論文選.