Lice were so prevalent during the middle ages that delousing became a social activity. People would sit down and have a chat or gossip while removing eachother’s lice.
In the late Middle Ages, books were so valuable that libraries would chain them to the bookcase. This was widely practiced until the 18th century.
Around 762, the demand for books in Baghdad was so high that any traders who brought books were given the weight of the books in gold in return.