Cosimo de' Migliorati, bishop of Bologna and a cardinal, commissioned this luxuriously decorated missal. It was made sometime between 1389 and 1404, the year in which he was elevated to the papacy as Innocent VII. A missal contains all the texts used for celebrating Mass, including all the chants sung by the choir but without musical notation. Only the musically elaborate portions sung by the celebrating priest are supplied with notation, suggesting that this book was designed to be used by the cardinal himself at the altar as he celebrated Mass. The elegant illuminations of the missal, consisting of decorated calendar pages, numerous historiated initials, ornamented borders, and miniatures, place the book within the tradition of Bolognese manuscript illumination. The manuscript's anonymous illuminator, known as the Master of the Brussels Initials, was trained in Bologna, a city whose book trade flourished due to the prestige and growth of the university. The Master's work is characterized by the use of vivid colors, heavily modeled figures, and borders teeming with drolleries, beasts, and acanthus leaves.