A book of hours is a private prayer book, which became popular in the thirteenth and fourteenth centuries as literacy levels among the European nobility increased. The books included specific prayers to be recited at certain times, or hours, of the day and night, and were often devoted to the Virgin Mary. A book of hours was a valuable object, and owning one was a sign of wealth. One of the most masterfully decorated books of hours from the fourteenth century is the Hours of Jeanne d’Evreux.