"[S]acred music is to be considered the more holy
in proportion as it is more closely connected with the liturgical action,
whether it adds delight to prayer, fosters unity of minds,
or confers greater solemnity upon the sacred rites"
- Sacrosanctum Concilium, 112
The Second Vatican Council tells us, "The musical tradition of the universal Church is a treasure of inestimable value, greater even than that of any other art. The main reason for this pre-eminence is that, as sacred song united to the words, it forms a necessary or integral part of the solemn liturgy." (Sacrosanctum Concilium, 112). This means that singing and music are not merely optional add-ons to the liturgy, but actually a constitutive part of its ideal celebration!
"In the choosing of the parts actually to be sung, preference is to be given to those that are of greater importance and especially to those which are to be sung by the Priest or the Deacon or a reader, with the people replying, or by the Priest and people together." (GIRM, 40)
The document Musicam sacram lays out an order of importance*
1st Degree:
The General Instruction gives four options for the source of the Entrance, Offertory, and Communion chants:
By Flowing Waters - Paul F. Ford (English adaptation of the Graduale Simplex, modern notation)
English Proper Chants - John Ainslie
Lalemant Propers - Simple psalm tone settings
Lumen Christi Simple Gradual - Adam Bartlett
Propers of the Mass for Sundays and Solemnities - Fr. Samuel Weber (English adaptations of the Gregorian chant melody for the antiphons, along with simplified versions and even simpler versions based on chant tones; in chant notation)
St. Meinrad Entrance and Communion Antiphons - Fr. Columba Kelly
Simple Choral Gradual - Richard Rice
Simple English Propers - Adam Bartlett
Spanish Propers Project - Settings of the proper antiphons in Spanish, with varying levels of complexity