Mochibian 墨池編 "About the ink pond" is a book on calligraphy written during the Northern Song period 北宋 (960-1126) by Zhu Changwen 朱長文 (1039-1098), courtesy name Boyuan 伯原, from Wuxian 吳縣 (today's Suzhou 蘇州, Jiangsu). He was a famous calligrapher and wrote the books Wujun tujing xuji 吳郡圖經續記, Caipu yugao 采圃餘稿 and Xu shuduan 續書斷. He was erudite of the National University (taixue boshi 太學博士) and proofreader of the Palace Library (mishusheng zhengzi 秘書省正字).
His book of 6 juan length (in oder versions 12 or 20) is divided into eight chapters expounding the style of Chinese characters (Zixue 字學), methods of the brush (Bifa 筆法), various discourses (Zayi 雜議), classification (Pinzao 品藻), laudation (Zanshu 贊述), collection (Baozang 寶藏), stele inscriptions (Beike 碑刻), and tools (Qiying 器用).
The book quotes extensively from older sources, like Yu Jianwu's 庾肩吾 (487-551) Shuping 書評 (Shupin 書品), Emperor Wu's 梁武帝 (r. 502-549) Shuping 書評, Li Sizhen's 李嗣真 (?-696) Houhuapin 後畫品, Zhang Huaiguan's 張懷瓘 (c. 730) Shuduan 書斷 or Dou Xi's 竇息 (fl. 769) Shushufu 述書賦. The chapter on stele inscriptions lists numerous titles and sites of documents. In all versions of the book, a supplementary list of inscriptions from the Song to the mid-Ming period 明 (1368-1644) is added.
The chapter on tools includes statements on brushes, ink-stones, paper, and ink, and is Zhu Changwen's genuine writing. Apart from quoting sources in the first five fascicles, Zhu also critically comments on them and highlights the most important aspects. The whole book is thus a valuable collection of knowledge of calligraphy, and surpasses Zhang Yanyuan's 張彥遠 (mid-8th cent.) Fashu yaolu 法書要錄 in depth and insight.