Name of a liturgical book, used during the Middle Ages, containing prayers, psalms, antiphons, responsories, hymns, lessons, versicles, and little chapters to be recited at the canonical hours. In the Armenian and Ruthenian Churches such books are still in use, but in the Latin Church they have been incorporated in the Divine Office or Breviary. The "Tres Riches Heures," a 15th-century manuscript in the Musee Conde, Chantilly, executed under the direction of the Duke of Berry and reputed to have been illuminated by the Limbourg brothers, is one of several beautiful Books of Hours still extant. It contains a calendar embodying a concrete, naturalistic conception of the seasons, the first attempt at modern landscape art. The "Grandes Heures" and the "Tres Belles Heures" (Brussels) of the Duke of Berry, the Book of Hours of Etienne Chevalier (Chantilly), and the Hours of Anne of Brittany (Paris) are similar.