William Durand's (ca. 1230–1296) Rationale divinorum officiorum (ca. 1292/1296) is unquestionably the longest and most thorough commentary on the liturgy produced by a medieval liturgiologist. From the time of its appearance at the end of the thirteenth century to the Catholic Restorationist liturgical revival in mid-nineteenth-century France, it was hailed by admirers as the quintessential expression of the medieval church's understanding of the divine offices. The bishop of Mende's Rationale treats, among other things, the various parts of the church building, the ministers of the church, liturgical vestments, and the Mass and the canonical hours. It thus stands as the epitome of a four-hundred year tradition of allegorical liturgical exposition which was inaugurated in the West with the extended liturgical commentaries of the Carolingian bishop, Amalarius of Metz (died 852/853).