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.
History of printing in East Asia
Given that the Chinese language does not use an alphabet it was usually necessary for a set of type to contain 100,000 or more blocks, which was a substantial investment. Common characters need 20 or more copies, and rarer characters only a single copy. In the case of wood, the characters were either produced in a large block and cut up, or the blocks were cut first and the characters cut afterwards. In either case the size and height of the type had to be carefully controlled to produce pleasing results. To handle the typesetting, Wang Zhen used revolving tables about 2m in diameter in which the characters were divided according to the five tones and the rhyme sections according to the official book of rhymes. The characters were all numbered and one man holding the list called out the number to another who would fetch the type.