This illuminated manuscript once served as a liturgical service book used on the high altar by a priest for the Mass. The missal’s colophon (inscription) identifies the book as belonging to the church of San Francesco in Montone, a convent of Franciscan friars, and gives its date of completion as October 4, 1469. Here, the volume is opened to its masterpiece, two pages that introduce the canon of the Mass, the most solemn part of the celebration during which the priest consecrates the Eucharistic bread and wine. The missal receives its name from the two Perugian artists who collaborated to illuminate its pages. Here, the Calvary scene featuring the crucified Christ flanked by the Virgin and Saint John is the work of Bartolomeo Caporali, and the marginal decoration and the facing page are likely the work of his brother, Giapeco. Saint Francis’s appearance at the foot of the cross attests to the missal’s Franciscan use and affiliation.