"The earliest example in England of a library to be endowed for the benefit of users who were not members of an institution such as a cathedral or college was the Francis Trigge Chained Library in Grantham, Lincolnshire, established in 1598. The library still exists and can justifiably claim to be the forerunner of later public library systems."

While free public libraries didn't take off until middle 1800s, there was still a lot of literature out on the streets thanks to the printing press. And a surprising number of people were literate in the middle ages.