A Catholic Book of Hymns - Noel Jones - Bog

Playing daily Masses for centuries, organists in Catholic churches had certain assigned chant melodies to be sung every year. They became so familiar with these melodies, that they would improvise organ pieces featuring the melody in different ways and play these settings for the Mass. Chants were sung unaccompanied most times and the organ played on its own at times. Also, a common practice was playing part of a chant on the organ in place of a verse or verses, in alternation with the choir. These compositions may be used in different ways - as a Prelude to the Mass, as an introduction to the singing of the hymn and, if a hymn is sometimes sung after Mass, as a Postlude to the Mass are the last verse is sung. There are pieces on each of the 295 hymns in A Catholic Book of Hymns, published by Sacred Music Library.