Cài Shěn 蔡沈 (1167–1230), zì Zhòngmò 仲默, hào Jiǔfēng 九峰, of Jiànyáng 建陽 (Fújiàn). CBDB id 10058. Sòngshǐ biography in juan 434, Rúlín zhuàn.
Second son of 蔡元定 (Cài Yuándìng, 1135–1198); younger brother of 蔡淵 (Cài Yuān, 1156–1236). Direct disciple of Zhū Xī. Took up his father’s exile companionship to Dàozhōu 道州 in 1196 and remained at his father’s side until Cài Yuándìng’s death in 1198.
Author of the Shū jí zhuàn 書集傳 (also Shàngshū jí zhuàn 尚書集傳) — composed at Zhū Xī’s express command after Zhū Xī’s death (1200), based on the unfinished Shū commentary materials Zhū Xī had assembled. The Shū jí zhuàn became the standard Shàngshū commentary of the YuánMíngQīng tradition and was canonized as the Shū’s authoritative gloss in the Yuán-period examination-system standardization (1313) and the Míng-period Sìshū wǔjīng dàquán (1415). Posthumous title (Yuán-period) Wénzhèng 文正.
Other surviving works: Hóngfàn huángjí nèi piān 洪範皇極內篇 (a treatise on the Hóngfàn’s number-cosmology, in 5 juan; preserved in the Sìkù). Considerable poetry and prose collected in Cài Jiǔfēng wénjí 蔡九峯文集.
The Cài family of Jiànyáng — Cài Fā → Cài Yuándìng → Cài Yuān / Cài Mò / Cài Shěn / Cài Háng → etc. — is the most important late-Sòng Dàoxué scholastic dynasty. Cài Shěn’s specific contribution was to extend the family-line scholarship from the Yì (Cài Yuándìng’s principal canonical specialty) to the Shū (his own contribution), thereby giving the Cài-school comprehensive coverage of the post-Zhū-Xī Five-Classics curriculum. Within the Kanripo corpus he wrote the postface (preserved by Zhū Yízūn’s Jīngyì kǎo) to his elder brother Cài Yuān’s Zhōuyì jīngzhuàn xùnjiě (KR1a0052).