A service book containing the texts necessary for the performance of the Mass (including chants, prayers, and readings), together with ceremonial directions. The prayers and other texts recited by the priest were originally contained in the Sacramentary, which was used together with the Gradual, the Evangelary, and the Epistolary for the performance of high or solemn mass. The missal was introduced in the Carolingian period and by the thirteenth century had supplanted the older Sacramentary, combining in one volume the various components for the performance of the mass. Its development was prompted by the custom of saying private masses and low masses, which were performed by the celebrant alone. Principal fields for decoration in the missal are the canon page (with the text Te igitur) and the Vere dignum monogram.
Michelle Brown, Understanding Illuminated Manuscripts (Malibu, CA: J. Paul Getty Museum in association with the British Library, c1994).