清中葉《易》學家程廷祚 (1691-1767)，研究進路屬於義理《易》。他反省時人治《易》常受歷代《易》學影響，未就經傳本身加以探究，因此他釋《易》不歸依程朱，並對歷代普遍使用的承、乘、比、應說法加以質疑。藉由〈繫辭傳〉，發展出易簡哲學，重視天人性命之理，以及開物成務的理想，其《易》學具有下列三點特性：一，異於前代《易》家著眼於六畫卦象，他著重三畫卦，以上、下二體之象釋卦爻辭。二，他的易簡哲學重視乾、坤，以其純陽、純陰之故。三，在三畫卦方面，他不取天、地、雷、風、坎、離、艮、兌等具體物象，而採抽象義的卦德，即健、順、動、入、陷、麗、止、說。程氏《易》學既包括對歷代《易》學的反省，亦有回到經傳本身的釋《易》實踐。《大易擇言》反映他對歷代《易》學的理解與檢視，《易通》則是他回歸經典的成果，值得後人重視。

Cheng Tingzuo was a Mid-Qing scholar of the Yijing 易經who endorsed areading of the text based in moral principles. Cheng reflected on the fact that hiscontemporaries’ views of the Yi were often influenced by the historical interpretationsfound in the commentarial tradition rather than their own readings of the work. As aresult of this reflective process, Cheng advanced an interpretation of the Yijing thatdiverged from the standard Cheng-Zhu position, and he expressed doubts regarding thereceived methods of explaining the text. Cheng’s Yi learning, which was based on theXicizhuan 繫辭傳section of the work, can be said to have three characteristics. First,Cheng differed from earlier scholars, who focused on the hexagrams, by emphasizingthe trigrams and by using the trigram images (from the upper and lower parts of thehexagrams) to explain the yao lines. Second, Cheng’s philosophy of yijian 易簡stressed the qian and kun trigrams because they represented, respectively, pure yangand pure yin. Third, Cheng did not adopt the concrete material images of the trigrams,but rather utilized the abstract meanings found in their corresponding virtues. Chengthus not only reassessed the inherited tradition of Yi scholarship, he also called for areturn to the actual interpretation of the text itself. His Dayi zeyan 大易擇言reflectshis understanding of earlier Yi learning, while his Yitong 易通 resulted from hisdecision to return to the classics. Both texts are worthy of our attention.