William Byrd's "Gradualia", a set of liturgical music published in 1605 and 1607, is one of the most important compositions of the English Renaissance. Byrd composed this collection based on the Roman Catholic liturgy at a time when this religion was illegal in England, and the performance of its liturgy was punishable by fines, imprisonment, or even death. Not only was it surprising that the normally politically careful Byrd chose to create a liturgical work, but it also went against his usual practice of taking a free approach to text setting - changing words or inserting additional text as he saw fit to suit his music. The Mass cannot be changed; and much of its text is not very inspiring. The challenge, then, to the composer was to find musical inspiration in a text that must be rigidly followed. The resulting work is one of the most unusual - and often misunderstood - collections in the English repertoire. Kerry McCarthy has undertaken to study how Byrd approached this task, its meaning both musically and philosophically/religiously. Combining both the cultural history of the dangers faced by Catholics who practiced their religion at this time with a very close reading of how Byrd created this work, McCarthy creates a book that will interest musicologists, religious historians, and students of Elizabethan English culture.