Manuscript, single leaf from a book of hours, 15th century, latin.
What is a book of hours?
The book of hours is a Christian devotional book popular in the Middle Ages. It is the most common type of surviving medieval illuminated manuscript. Like every manuscript, each manuscript book of hours is unique in one way or another, but most contain a similar collection of texts, prayers and psalms, often with appropriate decorations, for Christian devotion.
llumination or decoration is very changable in many examples, often restricted to decorated capital letters at the start of psalms and other prayers, but books made for wealthy patrons may be extremely lavish, with full-page miniatures. Books of hours were usually written in Latin, although there are many entirely or partially written in vernacular European languages, especially Dutch.
The English term primer is usually now reserved for those books written in English. Tens of thousands of books of hours have survived to the present day, in libraries and private collections throughout the world.