Chen Cang-qi, a native of Siming (present-day Ningbo, Zhejiang), served as the county captain of Sanyuan (now part of Shaanxi Province) in the capital region during the Kaiyuan era (713-741) of the Tang Dynasty. Because the Shennong Bencao Jing (Shennong's Classic of Materia Medica), despite having supplements by Tao and Su, still had many omissions, he compiled a preface and guidelines in one volume, supplements in six volumes, and resolutions of disputes in three volumes, collectively titled Bencao Shiyi (Supplement to Materia Medica), totaling ten volumes (as recorded in the New Book of Tang), completed in the 27th year of Kaiyuan (739). This work categorized the functions of medicinal substances into detoxification, breaking qi, treating warm diseases, regulating wind, and benefiting the spleen, among others, marking the origin of the functional classification of Chinese medicinals in later generations.

Li Shi-zhen remarked: "The writings of Cangqi are extensive in their coverage of books, meticulous in the examination of natural categories, correcting errors, and uncovering obscure knowledge. Since the time of materia medica, there has been no one like him! Superficial scholars, not understanding his detailed examinations, only mock his eccentricities, and many Song scholars also made deletions. How could they know that the variety of things in the world is infinite, and the hidden and manifest aspects of things differ between ancient and modern times? Usage varies with time, and names may change. How can one, with a narrow view, hastily criticize a man of extensive knowledge? For example, substances like Pihui Lei (a medicinal plant), sea horse, and {|121|}Hu Dou{|122|} (a type of bean) were obscure in the past but are used today. Items like {|123|}Yangtian Pi{|124|} (a type of lichen), lamp wick ashes, and worn-out fans are used by countless households. If not for this book's records, how could we verify them? This is why materia medica books should not shy away from being detailed and thorough." (As seen in the {|125|}Medical Texts Examination{|126|})