Fei caoshu 非草書 is a pamphlet against the writing style "grass script" (caoshu 草書). The author was Zhao Yi 趙壹 (c. 180 CE), courtesy name Yuanshu 元叔, from Xixian 西縣 in the commandery of Hanyang 漢陽 (today's Tianshui 天水, Gansu). He was famous for his rhapsodies (cifu 辭賦), for instance, Fengshi jixie fu 諷世嫉邪賦, which is a critique of the internal fights at the Eastern Han 東漢 (25-220 CE) court. Most of his writings are lost.
Zhao criticized the widespread use of the "separated-characer grass script" (zhangcao 章草) of the time which imitated the styles of Du Du 杜度 (late 1st cent. CE) and Cai Yuan 崔瑗 (78-143). His main argument was that this convenient and loose style of writing contradicted the spirit of Confucius. Users of the grass script were, he said, "weak in the skills and arts [as handed down in the Classics]" (jiyi zhi xi zhe 技藝之細者), and the grass script was therefore not adaptable in the local administration, at the court, during the evaluation of officials, and so on. This is all the more surprising, as the grass script was already relatively widely used during the time and de facto fulfilled the requirement Zhao demanded for a writing style, namely practicality (shang yong 尚用), and was, moreover, assessed by most contemporaries as "cherishing beauty" (shang mei 尚美).
Contemporary debates on the script and writing styles can also be seen in Cai Yong's 蔡邕 (132-192) essay Bilun 筆論 "On the brush" or Zhong Yao's 鍾繇 (151-230) Bifa 筆法 "Methods of the brush".
The text of the Fei caoshu is included in the series Yuhan Shanfang jiyi shu xubian 玉函山房輯佚書續編 and is quoted in the books Fashu yaolu 法書要錄, Shuyuan jinghua 書苑菁華 and Lidai shulun wenxuan 歷代書論文選.