St. Augustine said to sing is to pray twice. That may be why the first action of the liturgy is a song. You may have heard people say that first impressions are very important. That is certainly true in the liturgy. Many times you can judge how well the liturgy will go by how well the opening song goes. The singing of the opening song is the first thing we do together as a worshiping community. It is our way of saying, "Yes, God, we're all together and all of us are ready to pray now." It is very important that this hymn be one that is easy to sing and familiar to everyone.
The Second Vatican Council called for the conscious, active, and fruitful participation of all in the liturgy. Singing is one of the most important ways to achieve it. In actual practice, some people do not sing. Many do not even pick up the hymn book. Given the important of singing at Mass every effort should be made to help members of the assembly participate in this first ritual action of the liturgy. In some communities the leader of song invites the faithful to stand and greet those around them. This gives people permission to extend friendly greetings to those nearby with whom they will sing, pray, hear the word of God, and share Communion. It honors the silence that precedes the start of the Mass and serves a function separate from the sign of peace, which is part of the symbolism that specifically prepares the Communion. It allows a stranger to be welcomed and for the people to enter the first song as one - as a unified assembly.
Our official liturgical documents clearly state the purpose and intent of the opening song:
The entrance song should create an atmosphere of celebration. It helps put the assembly in the proper frame of mind for listening to the word of God. It helps people to become conscious of themselves as a worshiping community. The choice of text for the entrance song should not conflict with these purposes. (Music in Catholic Worship, number 61)
Even though pastoral experience may prove otherwise, the focus or role of the opening song is not to accompany the procession of the priest or other ministers. The purpose of the opening song is for the community to articulate and offer its worship, and to help them focus for the liturgical celebration. The Song of the Gathering is the opening "faith statement" of the gathered assembly; it serves to galvanize the room of individuals into a connected community of faith and prayer. In a very real sense, the opening song is truly the opening prayer for all who have gathered.
The opening song also has an evangelistic quality to it. On almost any occasion, there is a stranger or a newcomer in our midst as we gather for worship. We may not always know that somebody new is there, so we have to discipline ourselves to be conscious of the possibility. Whenever we have a guest present, we want to show ourselves at our best. So every time we gather to worship, we will want to sing our best, right from the start. Singing our best helps us also to enter into the spirit of the liturgy right from the start.
[Source: Supplement, St. Paul Roman Catholic Cathedral, Saskatoon, SK, Canada; May 2, 2010]