While the medieval book was made out of sheets, it is the quire that is the object's building block. A quire is a small package of folded sheets (bifolia
or double-leaves) made of parchment
. A medieval book consisted of twenty or more quires, which were held together by a binding
. How many bifolia or singletons a scribe would use for a quire depended on his geographical location, among other things.
Copyists in England often opted for six double-leaves, while their continental counterparts almost never did: they favored four. Some late-medieval manuscripts, especially Paris Bibles contained quires with a very high number of bifolia, eighteen or even more. Thick quires are also found up in manuscripts made by chancery clerks, such as account books. When you look at the top or bottom of a manuscript you van easily spot the individual quires, all cuddled up inside the binding.