Editing Roman Breviary (section)

=== The Psalter ===
{{main|Latin Psalters}}
This psalm book is the very backbone of the Breviary, the groundwork of the Catholic prayer-book; out of it have grown the antiphons, responsories and versicles. Until the 1911 reform, the psalms were arranged according to a disposition dating from the 8th century, as follows: Psalms 1–108, with some omissions, were recited at Matins, twelve each day from Monday to Saturday, and eighteen on Sunday. The omissions were said at Lauds, Prime and Compline. Psalms 109-147 (except 117, 118, and 142) were said at Vespers, five each day. Psalms 148-150 were always used at Lauds, and give that hour its name. The text of this Psalter is that commonly known as the Gallican. The name is misleading, for it is simply the second revision (A.D. 392) made by Jerome of the old ''Itala'' version originally used in Rome. Jerome's first revision of the ''Itala'' (A.D. 383), known as the Roman, is still used at St Peter's in Rome, but the "Gallican", thanks especially to St Gregory of Tours, who introduced it into Gaul in the 6th century, has ousted it everywhere else. The Antiphonary of Bangor proves that Ireland accepted the Gallican version in the 7th century, and the English Church did so in the 10th.<ref name=EB1911/>

Following the 1911 reform, Matins was reduced to nine Psalms every day, with the other psalms redistributed throughout Prime, Terce, Sext, and Compline. For Sundays and special feasts Lauds and Vespers largely remained the same, Psalm 118 remained distributed at the Little Hours and Psalms 4, 90, and 130 were kept at Compline.