Wang Xizhi is regarded by all those with a classical East Asian (Chinese, Japanese or Korean) eduction to have been China's greatest calligrapher. This is an astounding statement; for calligraphy is not a dead art. It has been practised continuously for the last sixteen hundred years or so. Perhaps something comparable in Western Civilization would be to assert that Praxiteles (4th century B.C.) is its greatest sculptor - not Donatello, not Michelagelo, not Rodin, etc. Or to say that the "Winged Nike of Samathrace" 2nd century A. D. Hellenistic sculpture, rediscovered in the 19th century and now in the Louvre is the greatest work of sculpture. But there you are; ask any traditionally educated Chinese, Japanese or Korean--it is Wang Xizhi, who lived in the 4th century A. D., whose works are all lost and remain only in copies.
Undoubtedly it is due to the fact that Chinese civilization has survived continuously for nearly three thousand years (five thousand years over-states the case and includes the period that Chinese tradition has written about) as well as the fact that the bearers of this civilization has remained a self-perpetuating scholar-gentry class supported most of the time by the state. The second Tang emperor was said to have commissioned a search for Wang's most famous work--his preface to a collection of poems that celebrated a picnic at an Orchid Pavilion near modern-day Hangzhou (famous today partly because Henry Kissinger cattily recorded Nixon's philistine remark upon visiting it was that it was as pretty as a picture post-card). That emperor decreed that the original manuscript be buried with him and so it was but it appears that three copies were made that include even Wang's crossing out of his mistakes or imperfections. These survived as stone copies and have since then been faithfully copied and recopied. The text and pictures may be viewed on-line at http://www.chinapage.com/calligraphy/wangxizhi/wangxizhi.html.
It is not long, only a few over 400 characters or "graphs" long, introducing what became "nature poetry" in Chinese literature. The whole is reproduced in three panels that should be read from right to left, below. It is said that Wang was a calligrapher of such infinite variety that he wrote the word zhi (之) a common particle, that appears 21 times, such that no two instances are exactly the same. Each instance, the graph is ever so slightly different due to the the rhythms of its surrounding graphs. It is as if Jefferson had written the letter "e" differently each time it appeared in the Declaration of Independence, but of course, calligraphy in Chinese civilization is not to be equated with penmanship in the English language. The following pictures are from the website noted above.