Books of hours were among the most common devotional texts of the Middle Ages. Produced throughout western Europe until the early 16th century, books of hours were important status items, often elaborately illuminated, that might be tailored to the specific tastes of well-heeled clients to reflect interests in particular saints or to incorporate other elements of their personal lives and religious, political, or social commitments. Although the specifics of its origin remain uncertain, the APS Book of Hours is organized in a fairly typical fashion. Beginning with a calendar specifying feast days and other holy days, the book includes readings from the gospels, prayers (Obsecro te, O Intemerata), the Hours of the Virgin, the Hours of the Cross, the seven penitential psalms (6, 31, 37, 50, 101, 129), the litanies and prayers, the office for the dead, and additional prayers devoted to Saints Barbara, Anthony, Margaret, and Sebastian. Each of the 22 sections begins with a full-page illustration, many with additional vignettes. An additional vignette of a figure of death is included in the office of the dead. The volume was donated to the APS by Detmar Basse-Müller in 1806.