Before the invention of the printing press, almost all books were copied by hand, which made books expensive and rare. Different types of ink were known in antiquity, usually prepared from soot and gum, and later also from gall nuts and iron vitriol. This gave writing a brownish black color, but black or brown were not the only colors used. At first, books were copied mostly in monasteries, one at a time.
With increasing number of universities in the 13th century, the manuscript culture of the time led to more demand for books, and a new system for coping books began.
Books were divided into unbound leaves (pecia), which were lent out to different copyist, so the speed of book production was considerably increased. At one in time religious books were incredibly costly to make, and therefore extremely valuable, so they were kept in chained libraries. Such libraries allowed people to read only, and not taken away, though some were still stolen. In Wells Cathedral, you find only the chain without the books!
There are still some chained libraries with their books intact in English churches. Among the most famous is the 17th-century library.