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. If a medieval psalter has any decoration at all, it will be on the first words of Psalm 1. In opulently decorated psalters like this one, the initial of the first psalm will be spectacular. The initial is filled with an intricately rendered vine, which forms multiple spirals inhabited by struggling beasts. More fanciful creatures embellish the letter's exterior, with the whole set upon a meticulously patterned field within a frame. At the corners, round pictures of David show him rescuing the lamb from the lion, being anointed king, casting his sling at Goliath and beheading Goliath.