Yang Xi
Although no autograph copies of Yang Xi's famous calligraphy have survived, one well-documented stone rubbing version of the revealed "Huangting jing" (黃庭經, Yellow Court Scripture) has been given special attention. The Song dynasty connoisseur and critic Mi Fu (1051-1107) analyzed four manuscripts of the "Huangting jing", and said the best one was written on a silk scroll with a provenance that he traced back to the early 8th century. Mi disagreed with a former owner Tao Gu (陶穀, 903-970) who said that Wang Xizhi wrote the manuscript, and concluded it was a superb example of calligraphy from the Six Dynasties period. The Ming dynasty calligrapher and painter Dong Qichang (1555-1636) was so impressed by the Mi Fu manuscript that he made a copy, recommend it as the best model for studying "kaishu" script, and included it as the first example in his classic "Xihong tang fatie" (戲鴻堂法帖, Calligraphy Compendium of the Hall of the Playful Goose). Dong's colophon attributed the calligraphy to Yang Xi himself and described it as "the traces of a holy immortal" (Ledderose 1984: 262-263, who calls Dong's attribution to Yang "extremely optimistic").
Codex
The earliest surviving fragments from codices come from Egypt, and are variously dated (always tentatively) towards the end of the 1st century or in the first half of the 2nd. This group includes the Rylands Library Papyrus P52, containing part of St John's Gospel, and perhaps dating from between 125 and 160.
In Western culture, the codex gradually replaced the scroll. Between the 4th century, when the codex gained wide acceptance, and the Carolingian Renaissance in the 8th century, many works that were not converted from scroll to codex were lost. The codex improved on the scroll in several ways. It could be opened flat at any page for easier reading, pages could be written on both front and back (recto and verso), and the protection of durable covers made it more compact and easier to transport.