Book VIII of Rationale Divinorum Officiorum, by Guillaume Durand, early 14th century

MS 139 contains the eighth book of Guillaume Durand's 'Rationale Divinorum Oficiorum', a text on the ritual of the medieval Church, and therefore presents a good outline of the medieval liturgy in the 13th-century West. Durand's text was extremely popular during the Middle Ages, and was frequently copied. The text of the eight book, as it appears in MS 139, ends on f. 88v with the words et aliis preciosis sumptibus urbem lustrant. Explicit speculum rationale super compoto et kalendario editum a magistro Gulielmo duranti