Northern-Sòng Yìxué scholar, zì Chízhèng 持正. Pupil and correspondent of 程頤 Chéng Yí; the surviving letter from Chéng to Xiè Shí — preserved in 邵伯溫 Shào Bówēn’s Wénjiàn qián lù 聞見前錄 — gives the locus classicus of Chéng’s instruction on the Yì: “Reading the Yì, one should first study the three masters — 王弼 Wáng Bì, 胡瑗 Hú Yuán, and 王安石 Wáng Ānshí.”