Throughout most of history most people have been illiterate. In feudal society, for example, the ability to read and write was of value only to the clergy and aristocracy. The first known reference to "literate laymen" did not appear until the end of the 14th cent. Illiteracy was not seen as a problem until after the invention of printing in the 15th cent. The first significant decline in illiteracy came with the Reformation, when translation of the Bible into the vernacular became widespread and Protestant converts were taught to read it. Revolutionary political movements from the 18th to the 20th cent. generally included an attack on illiteracy as one of their goals, with the former Soviet Union, China, and Cuba being among the most successful in the 20th cent.