How many words are written on the back of Mrs. Wei's pen drawing?

More than 500 words. "Bi Tu" was written by the old lady Wei. Later, there were different opinions, either it was written by Wang Xizhi or it was a calligraphy work entrusted by people in the Six Dynasties. There are only more than 500 words in the brush drawing, with concise strokes and general words. This book discusses the works of writing strokes, expounds the methods of writing and using pens, and lists seven basic strokes.