If we define printing as the process of transferring repeatable designs onto a surface, then the first known printing was done by the Mesopotamians, who as early as 3000 b.c. used stamps to impress designs onto wet clay. Printing on paper developed much later; Chinese inventor Ts'ai Lun (50?-118? a.d.) produced the first paper in 105 a.d. Chinese books printed with inked wood blocks survive from the T'ang Dynasty (618 a.d.-907 a.d.), and it was the Chinese--not German printer Johannes Gutenberg, as is widely believed--who developed movable type, allowing printers to compose a master page from permanent, raised characters. Pi Sheng invented movable type around 1045; he fashioned his characters of heat-fired clay. Later printers improved on his design by using characters made from lead. However, movable-type printing did not achieve the popularity in medieval China that it later would in Europe; as the...