A book, also called a primer or horae, for use in private devotions. Its central text, the Little Office of the Blessed Virgin (or Hours of the Virgin), is modelled on the Divine Office and represents a shorter version of the devotions performed at the eight canonical hours. The text, known from the tenth century, was originally read only by ecclesiastics; it entered into more popular use by the end of the twelfth century, often being attached to the Psalter, the book more commonly used for private devotions before the emergence of the book of hours. The private recitation of the Little Office of the Virgin is an expression of the lay person's desire to imitate the prayer-life of the religious. The Little Office of the Virgin gradually acquired other elements: a liturgical calendar, a litany of the saints, suffrages, the Office of the Dead (which had emerged by the ninth century), the Penitential Psalms (Psalms 6, 31, 37, 50, 101, 129, and 142, which were first included in books of hours in the thirteenth century), the Gradual Psalms (Psalms 119-133), and prayers. Additional offices, such as the Short Office of the Cross, Hours of the Holy Spirit, Hours of the Trinity, and Hours of the Passion, could also form part of a book of hours. The book of hours took its standard form in the thirteenth century and continued in general use until the sixteenth century, enjoying particular popularity in France and Flanders. The texts of books of hours vary slightly in accordance with use. Books of hours were medieval best-sellers and have survived in relatively high quantity. They are nearly always illuminated, in a manner commensurate with the patron's budget, and often contain a miniature or set of miniatures for each major textual division. These subjects include scenes from the life of the Virgin, Christ, and King David, depictions of the saints and themes relating to death and judgment. The patron was also sometimes portrayed. Decorated letters as well as images can be found in books of hours.