Over the past several weeks, we've talked about the roles of priest, deacon and lay people at Mass. Now we'll begin to look at specific elements of the Mass and how we as members of the body of Christ take part in the celebration.

At every Mass, the priest and the assembly share a dialogue: The priest prays to God in the name of the assembly, and members of the assembly join their hearts and minds to that prayer. We show this interior union of prayer through outward gestures and words. That's why unity of word and gesture in our worship is so important. In addition, the priest and assembly share directly in a prayerful dialogue at times.

As the General Instruction on the Roman Missal points out: "Outward signs foster, strengthen, and express faith. There must be the utmost care, therefore . . . to make wise use of those forms and elements provided by the Church which . . . will best foster active and full participation, and properly serve the spiritual well being of the faithful."

The Mass consists of the Liturgy of the Word and the Liturgy of the Eucharist. These begin with the Introductory Rites of the Mass and close with the Concluding Rite. The Introductory Rites include the opening liturgical song, greeting, act of penitence, Kyrie, Gloria, and opening prayer. Each of these elements has a long history.

As the General Instruction reminds us, the Mass begins after the assembly has already gathered. This is important. The opening liturgical song usually occurs along with the procession of the celebrant and ministers of the Mass. In recent years, people have tended to call this moment a "gathering," or to sing a "gathering song" at this time. That's not quite accurate. A gathering song may help an assembly dispose themselves for the celebration of the Eucharistic mysteries, but it should be sung before the beginning of Mass itself.

Instead, the opening song should be either biblical or relate to the current liturgical season or feast, and it should help to deepen the unity of those assembled. In the opening song, we acknowledge that we've come together to praise our God. As the assembly members all stand we affirm our unity and our desire to take part in the act of worship.

The priest and other ministers usually enter in procession. We may see flickering candles and a display of color as members of the procession move in harmony, often entering the assembly from the back of the church, with the crucifix leading the way. The crucifix reminds us that Christ has brought us together through his sacrifice, and that he desires that, together, we should "do this in memory of me."

The procession may also include the Book of the Gospels. Entering thus and richly decorated, this most sacred part of the Word of God for Christians receives special veneration. This is why the Lectionary is never carried in procession, but only the Book of the Gospels. The deacon normally carries the book but another may do so in his absence. The book is placed on the altar to show the unity of the Liturgy of the Word and the Liturgy of the Eucharist

The priest and deacon dress in appropriately colored liturgical vestments to remind us that during the eucharistic sacrifice we celebrate a particular liturgical feast or mystery. Last in procession comes the celebrant, who stands among us as Christ. In joining our attention to these opening moments of the celebration, we take part in the dignity of the procession as the priest who brings Christ within our midst, and all those with him, move toward the altar.

From beginning to end, every word and gesture of the Mass has meaning. The more deeply we understand those meanings, the more deeply we take part in the worship of God, and in God's presence among us in the Eucharist.

Next week: more on the Introductory Rites.