History of education
Although there are more than 40,000 Chinese characters in written Chinese, many are rarely used. Studies have shown that full literacy in the Chinese language requires a knowledge of only between three and four thousand characters.
A Book from the Sky
The book is composed using a set of 4,000 characters, as this is roughly the number of characters in common usage in modern written Chinese. These characters were designed on the basis of the Kangxi radicals, so that “in terms of density of strokes and frequency of occurrence, they… appear, on the page, to be real characters“. In addition to these, page and fascicle numbers were indicated using tally marks based on the Chinese character 正.