The Renzi 任子 "Master Ren" is a philosophical treatise by the Later Han period 後漢 (25-220) scholar Ren Yi 任奕. There is not much known about his life. The imperial bibliography Jingjizhi 經籍志 in the official dynastic history Suishu 隋書 lists a 10 juan "scrolls" long book Renzi daolun 任子道論, written by a certain Daoist Ren Gu 任嘏 from the Wei period 曹魏 (220-265), but does not mention Ren Yi. Ma Zong 馬總 quotes from the Renzi in his story collection Yilin 意林. In some sources, he is called Ren Shuang 任爽, in others Ren Bian 任弁. According to the bibliography in the Suishu, the book Renzi is classified as a Daoist book, but a statement in the book Guiji dianlu 會稽典錄 quoted in the Sanguozhi 三國志, Ren Gu was a Daoist, while Ren Yi was a Confucian.
Fragments from the Renzi are included in Ma Guohan's 馬國翰 reconstruction of lost books (Yuhan shanfang jiyi shu 玉函山房輯佚書), and in the collectaneum Siming congshu 四明叢書.
Source: Li Xueqin 李學勤, Lü Wenyu 呂文鬰 (1996). Siku da cidian 四庫大辭典, vol. 2, p. 1546. Changchun: Jilin daxue chubanshe.