The Introductory Rites

"The Eucharist is 'the source and summit of the Christian life.'"The other sacraments, and indeed all ecclesiastical ministries and works of the apostolate, are bound up with the Eucharist and are oriented toward it. For in the blessed Eucharist is contained the whole spiritual good of the Church, namely Christ himself, our Pasch." 
"[The Eucharist] is the culmination both of God's action sanctifying the world in Christ and of the worship men offer to Christ and through him to the Father in the Holy Spirit."
"Finally, by the Eucharistic celebration we already unite ourselves with the heavenly liturgy and anticipate eternal life, when God will be all in all." (CCC 1324-26)
The celebration of the Holy Sacrifice of the Mass has been "the source and summit" of our lives as Catholics ever since Christ's sacrifice upon the Cross. As a result, it is "right and just" to put emphasis on the celebration of such great a mystery that unites us to the cross of Christ and to heaven itself.

Unfortunately, many of us do not understand the gravity of a Mass and how it can truly change our lives. It is easy to get caught "going through the motions" and so that is why we will be spending the next few weeks explaining the vital importance of the Mass and taking you step by step into the most profound meeting of heaven and earth.

We will start at the beginning of Mass, with what is called the "Introductory Rites."
"The rites preceding the Liturgy of the Word, namely the Entrance, Greeting, Act of Penitence, Kyrie, Gloria, and Collect, have the character of a beginning, introduction, and preparation. Their purpose is to ensure that the faithful who come together as one establish communion and dispose themselves to listen properly to God's word and to celebrate the Eucharist worthily." (General Instruction of the Roman Missal, GIRM 46)
The Entrance: "After the people have gathered, the Entrance chant begins as the priest enters with the deacon and ministers." (GIRM, 47)

This entrance procession before the liturgy begins has a rich history as is related by Henri-Daniel Rops:
"In the early days of the Roman Church, the Pope went from the Lateran Palace in a solemn cortege of his attendant clergy, deacons, and acolytes, to the particular sanctuary in which Mass was, that day, to be said...In it lies the origin of the processional entrance. Psalms were chanted by alternating choirs...psalms which were specially chosen for their consonance with the underlying intention of the particular day's sacrifice....Thus the Introit [also called the Entrance Antiphon] became an entrance-song...which, by a few brief words, states the theme or point of emphasis of the Mass." (This is the Mass, 40)
Currently in the Church, we retain the tradition of reciting or singing a psalm as the "Entrance Antiphon" which is based on the theme for the Mass of the day. In the GIRM, there are four options that are permissible to worthily celebrate the entrance procession:
(1) the antiphon from the Roman Missal or the Psalm from the Roman Gradual as set to music there or in another musical setting; (2) the seasonal antiphon and Psalm of the Simple Gradual; (3) a song from another collection of psalms and antiphons, approved by the Conference of Bishops; (4) a suitable liturgical song similarly approved by the Conference of Bishops or the Diocesan Bishop.
If there is no singing at the entrance, the antiphon in the Missal is recited either by the faithful, or by some of them, or by a lector."
The Church encourages parishes to sing the Introit in English. The Church Music Association of America has been working on a project to offer these English Introits to all parishes and can be found here. However, it is also permissible to select a hymn that reflects the general theme of the day. This helps those present at Mass to prepare and presents a sort of "prelude" to the readings that will be read.