Written Chinese
Because the majority of modern Chinese words contain more than one character, there are at least two measuring sticks for Chinese literacy: the number of characters known, and the number of words known. John DeFrancis, in the introduction to his "Advanced Chinese Reader", estimates that a typical Chinese college graduate recognizes 4,000 to 5,000 characters, and 40,000 to 60,000 words. Jerry Norman, in "Chinese", places the number of characters somewhat lower, at 3,000 to 4,000. These counts are complicated by the tangled development of Chinese characters. In many cases, a single character came to be written in multiple ways. This development was restrained to an extent by the standardization of the seal script during the Qin dynasty, but soon started again. Although the "Shuowen Jiezi" lists 10,516 characters—9,353 of them unique (some of which may already have been out of use by the time it was compiled) plus 1,163 graphic variants—the "Jiyun" of the Northern Song Dynasty, compiled less than a thousand years later in 1039, contains 53,525 characters, most of them graphic variants.
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.