本文的論域，主要以戴璉璋先生針對成玄英重玄學的研究，所標舉出的實踐智慧學為觀察通孔，企圖深化其重玄老學中以玄智觀照玄理的玄聖形象。清理出聖智光明，妙契重玄的內在義路有二：其一是境智雙遣、能所兩忘的重玄思維與工夫。此部分說明聖人如何以其至忘妙智契會重玄之道，由「境智兩冥，能所相會」至「境智雙遣，能所兩忘」的實踐路數，分析重玄工夫的連續性光譜，即是由「即境即智」至「非境非智」的心神鍛鍊，進而臻至精神獨立自由的解脫境界；其二則是即寂即動、非寂非動的重玄理境。此部分則為彰顯聖人和光同塵的應世取向，說明聖者與俗塵互動交流的維度，主要即透過寂而動、動而寂的循環反復，以正反互陳的辯證方式，推闡寂不乖動、動不乖寂，乃至於即寂即動、非寂非動的重玄理境。

The purpose of this article is to highlight the image of Xuansheng that views the principle of the abstruse through the agency of metaphysical wisdom put forward by Cheng Xuanying. To achieve this goal, it will draw on Tai Lian-chang's learning of ＂practical wisdom＂ developed in his research on Cheng Xuanying's metaphysics. It will illustrate the two sides of Cheng Xuanying's inner philosophical logic, which encompasses the theory of cultivation and the ideal realm of being a saint in Laozi's thought. Besides, it will indicate the philosophical characteristics of the study of Laozi in the Tang Dynasty.