The liturgical book known simply as a “gradual” was the principal choir book used during the Mass. They were produced in multiple volumes, sometimes as many as 12, in order to cover the entire liturgical year. Every church required a set of graduals in addition to other liturgical books such as missals, antiphonaries, and gospel lectionaries. This volume appears to be the lone survivor from a larger set. Its illuminations were painted by an illuminator working in the circle of the much-esteemed and highly imitated painter Girolamo dai Libri of Verona, who was a prolific painter of altarpieces as well as illuminations for books.