The Essentials of Calligraphy compiled a total of 39 works on calligraphy theory from the Eastern Han Dynasty to the Yuanhe period of the Tang Dynasty. Some of them only have their titles, but only 34 articles are left. Among them, Zhao Yi's "Against Cursive Script", Yang Xin's "Collecting the Names of Ancient Calligraphers", Wang Sengqian's "On Calligraphy", Zhang Huaiguan's "Book Judgment" are all famous works in ancient calligraphy theory. The widely circulated "Bizhentu" attributed to Wei Suo and "Postscript to Bizhentu" by Wang Xizhi are also included. The "Brief Catalogue of the Complete Library in the Four Treasures" calls it "a collection of complex works, and later scholars who discuss calligraphy generally use this as a basis."