Yixialun 夷夏論

Yixialun 夷夏論 "About the barbarian and the Chinese [religions]" was a treatise written by the Southern Dynasties period 南朝 (420~589) scholar Gu Huan 顧歡, courtesy name Gu Jingyi 顧景怡, who lived under the Southern Qi dynasty 南齊 (479-502). He came from a poor family in Wujun 吳郡 (modern Haining 海寧, Zhejiang) and became a retainer of the scholar Lei Cizong 雷次宗. Later on he settled down on Mt. Tiantai 天臺山, one of the holy mountains of Chinese Buddhism, but dedicated himself to Daoist studies in later years. He submitted a political treatise to Emperor Gaodi 齊高帝 (r. 479-482) that was called Zhigang 治綱. Gu Huan has also written the treatise Sanminglun 三名論 and comments to Wang Bi's 王弼 interpretation of the "Book of Changes" Yijing 易經. Except a few fragments his writings are lost.
The Yixialun is first mentioned in Gu's biography in the official dynastic historyofficial dynastic history Nanqishu 南齊書. It is also listed in the imperial bibliography Jingjizhi 經籍志 in the history Suishu 隋書, but not in those of the histories Jiutangshu 舊唐書 and Xintangshu 新唐書 which shows that is was lost before the end of the Tang period. In the book Gu Huan compared Buddhism and Daoism and analysed their common features, He came to the conclusion that both were actually one and the same belief (Dao ze Fo ye, Fo ze Dao ye 道則佛也，佛則道也). Although their basics and their traces contradicted each other, their holiness was conguent (qi sheng ze fu 其聖則符). Gu Huan's book was heavily criticized by Daoist scholars like Yuan Can 袁粲, Minister of Education (situ 司徒) of the Liu-Song period 劉宋 (420-479). The surviving fragements were collected by the Qing period 清 (1644-1911) scholar Ma Guohan 馬國翰. They are to be found, together with Yuan Can's critique, in his reprint series Yuhanshanfang jiyi shu 玉函山房輯佚書.