been a Catholic. Addressing Petre (who is known to have lent him money to advance the printing of the collection), Byrd describes the contents of the 1607 set as "blooms collected in your own garden and rightfully due to you as tithes", thus making explicit the fact that they had formed part of Catholic religious observances in the Petre household. The greater part of the two collections consists of settings of the Proprium Missae for the major feasts of the church calendar, thus supplementing the Mass Ordinary cycles which Byrd had published in the 1590s. Normally, Byrd includes the Introit, the Gradual, the Alleluia (or Tract in Lent if needed), the Offertory and Communion. The feasts covered include the major feasts of the Virgin Mary (including the votive masses for the Virgin for the four seasons of the church year), All Saints and Corpus Christi (1605) followed by the feasts of the Temporale (Christmas, Epiphany, Easter, Ascension, Whitsun, and Feast of Saints Peter and Paul (with additional items for St Peter's Chains and the Votive Mass of the Blessed Sacrament) in 1607. The verse of the Introit is normally set as a semichoir section, returning to full choir scoring for the Gloria Patri. Similar treatment applies to the Gradual verse, which is normally attached to the opening Alleluia to form a single item. The liturgy requires repeated settings of the word "Alleluia", and Byrd provides a wide variety of different settings forming brilliantly conceived miniature fantasias which are one of the most striking features of the two sets. The Alleluia verse, together with the closing Alleluia, normally form an item in themselves, while the Offertory and the Communion are set as they stand. In the Roman liturgy there are many texts which appear repeatedly in different liturgical contexts. To avoid having to set the same text twice, Byrd often resorted to a cross-reference or "transfer" system which allowed a single setting to be slotted into a different place in the liturgy. Unfortunately, this practice sometimes causes confusion, partly because normally no rubrics are printed to make the required transfer clear and partly because there are some errors which complicate matters still further. A good example of the transfer system in operation is provided by the first motet from the 1605 set (Suscepimus Deus a5) in which the text used for the Introit has to be reused in a shortened form