the calendar at the beginning, the order is random and can be customized for the recipient or region. The Hours of the Virgin were regarded as the most important, and therefore subject to the most lavish illustration. The Très Riches Heures is rare in that it includes several miracles performed before the commencement of the passion (Cazelles and Rathofer 1988). Calendar gallery Fuller descriptions are available at a University of Chicago website. Technique Vellum The parchment or vellum used in the 206 folios is fine quality calfskin. All bi-folios are complete rectangles and the edges are unblemished and therefore must have been cut from the centre of skins of sufficient size. The folios measure 30 cm in height by 21.5 cm in width, although the original size was larger as evidenced by several cuts into the miniatures. The tears and natural flaws in the vellum are infrequent and almost go unnoticed (Cazelles and Rathofer 1988). Illustrations The ground colors were moistened with water and thickened with either gum Arabic or tragacanth gum. Approximately ten shades are used besides white and black. The detailed work required extremely small brushes and probably a lens (Longnon, Cazelles and Meiss 1969). Contents The contents of the book are typical of those of a book of hours, though the quantity of illumination is extremely unusual. The Calendar: Folios 1–13 A generalized calendar (not specific to any year) of church feasts and saints' days, often illuminated with representations of the Labours of the Months, is a usual part of a book of hours, but the illustrations of the months in the Très Riches Heures are exceptional and innovative in their size, and the best known element of the decoration of the manuscript. Up to this point any scenes of the labours had been smaller images on the same page as the calendar text, though later 15th-century calendars often adopted the Limbourg's innovation of a full-page miniature, though most had smaller pages than here. They were also unprecedented in mostly showing one of the duke's castles in the background. They are filled with details of the delights and labors of the months, from the Duke's court to his peasants, a counterpart to the prayers of the hours. Each illustration is surmounted with its appropriate hemisphere showing a solar chariot, the signs and degrees of the zodiac, and numbering the days of the month and the martyrological letters