Used as a prayerbook as well as a book of hymns for church services, the psalter in the later middle ages was often produced with a calendar and additional prayers. Eventually it was combined with an abridged version of the breviary, the prayerbook used by monks, to form the special lay prayerbook, the book of hours. This psalter represents an important stage in this development as it took place in England. It is one of the earliest psalters to include the Hours of the Virgin, a special set of devotions taken from the breviary. Also it is the earliest of a line of richly decorated psalters which were probably made at Oxford, in the workshops by lay scribes and artists, an industry which grew out of book production for the university. Each psalm in this book begins with a historiated initial, decorated with gold and figures painted in rich colours. Psalm 41 (42), "As the deer thirsts for fountains of water, so my soul longs for you, God," has a 'portrait' of David, believed to be the author, who holds up a scroll, the ancient form of book. Below a deer slakes its thirst by drinking from a spring. In this deluxe presentation, lines of short verses are filled out with drawings of fanciful creatures, a human head and vine ornament.