Antiphonary in the context of "Pope Pius X"

A psalter is a volume containing the Book of Psalms, often with other devotional material bound in as well, such as a liturgical calendar and litany of the Saints. Until the emergence of the book of hours in the Late Middle Ages, psalters were the books most widely owned by wealthy lay persons. They were commonly used for learning to read. Many psalters were richly illuminated, and they include some of the most spectacular surviving examples of medieval book art.

The English term (Old English psaltere, saltere) derives from Church Latin. The source term is Latin: psalterium, which is simply the name of the Book of Psalms (in secular Latin, it is the term for a stringed instrument, from Ancient Greek: ψαλτήριον psalterion).The Book of Psalms contains the bulk of the Divine Office of the Roman Catholic Church. The other books associated with it were the Lectionary, the Antiphonary, and Responsoriale, and the Hymnary.In Late Modern English, psalter has mostly ceased to refer to the Book of Psalms (as the text of a book of the Bible) and mostly refers to the dedicated physical volumes containing this text.

Guido of Arezzo (Italian: Guido d'Arezzo; c. 991–992 – after 1033) was an Italian music theorist and pedagogue of High medieval music. A Benedictine monk, he is regarded as the inventor—or by some, developer—of the modern staff notation that had a massive influence on the development of Western musical notation and practice. Perhaps the most significant European writer on music between Boethius and Johannes Tinctoris, after the former's De institutione musica, Guido's Micrologus was the most widely distributed medieval treatise on music.

Biographical information on Guido is only available from two contemporary documents; though they give limited background, a basic understanding of his life can be unravelled. By around 1013 he began teaching at Pomposa Abbey, but his antiphonary Prologus in antiphonarium and novel teaching methods based on staff notation brought considerable resentment from his colleagues. He thus moved to Arezzo in 1025 and under the patronage of Bishop Tedald of Arezzo he taught singers at the Arezzo Cathedral. Using staff notation, he was able to teach large amounts of music quickly and he wrote the multifaceted Micrologus, attracting attention from around Italy. Interested in his innovations, Pope John XIX called him to Rome. After arriving and beginning to explain his methods to the clergy, sickness sent him away in the summer. The rest of his life is largely unknown, but he settled in a monastery near Arezzo, probably one of the Avellana of the Camaldolese order.