‘When the Entrance Chant is concluded, the Priest and the faithful, standing, sign themselves with the Sign of the Cross.

‘The priest stands in persona Christi capitis—in the person of Christ the head — while the faithful constitute the members of Jesus’ Mystical Body… for the Eucharist is always the action of Christ, head and members, lived out in the life of the Church’ (Msgr. Caron, “The Introductory Rites for Mass”).

The priest greets the people, recalling Saint Paul’s greetings in the Lord (Galatians 6:18; Philippians 4:23). To the greeting, ‘The Lord be with you,’ we reply, ‘And with your spirit,’ acknowledging the Holy Spirit working through the priest during the Sacred Liturgy of the Eucharist.

We prepare for faithful celebration by making a Penitential Act, to purify our hearts and minds to better partake of the Eucharist.  While this general confession pardons venial sins, it ‘lacks the efficacy of the Sacrament of Penance’ (GIRM # 51).  We may bow our heads to recollect ourselves in a brief examination of conscience. We may orient ourselves toward the altar to remind ourselves of Christ’s presence in our midst.

The priest invites the faithful into the Penitential Act, which may be in one of three forms:

• the Confiteor, ‘I confess…’ (see 1 Chronicles 21:8; Luke 7:47; Luke 18:13). We recite our general confession together, striking our heart at the threefold ‘through my fault, through my fault, through my most grievous fault…’
• the Dialogue, where the priest entreats:
  
  • Have mercy on us, O Lord ℟ For we have sinned against You
    (Baruch 3:2)
  • Show us, O Lord, your mercy ℟ And grant us Your salvation
    (Psalm 85:8)
• the Tropes, where the priest, deacon, or other minister (such as the cantor with a choir) invokes the Kyrie Eleison, Lord, have mercy (Psalm 25)
  • You were sent to heal the contrite of heart… (Psalm 147:3)
  • You came to call sinners… (Matthew 9:13)
  • You are seated at the right hand of the Father to intercede for us… (Romans 8:34)

If the Penitential Act does not include it, the Trinitarian triplets of the Kyrie Eleison are said or sung with the cantor and choir. The Church reaches back to its ancient Greek Tradition to implore God’s mercy as the Divine Physician, with the Greek word eleos having the same root as the Greek word for olive oil, to soothe and heal our wounds, as in the Anointing of the Sick.

We chant the Gloria in excelsis (Glory to God in the highest), the “most ancient and venerable hymn by which the Church, gathered in the Holy Spirit, glorifies and entreats God the Father and the Lamb” (GIRM # 53). This joining in the heavenly host praising God’s Glory begins from Luke 2:13. We praise and thank our heavenly Father who reveals His glory throughout Creation and His saving Love for us throughout Salvation History. We in turn are called to respond in love, that there may be peace on Earth (Benedict XVI, Homily on the Solemnity of the Nativity of the Lord, 2010).

We then collectively call to mind our intentions for the celebration of the Eucharist in the Collect prayer, which we all make our own, with our ‘Amen.’ “The prayer ascends to the Father ‘through Jesus Christ,’ the mediator (‘…No one comes to the Father but through me’ John 14:6), and in the Holy Spirit, the Paraclete and Advocate, who is the personified union between Father and Son as well as the uniting force between the Church and God” (William Saunders, ‘Exploring the Beauty of the Mass’).
“Each celebration of the Eucharist communicates special graces to us, and the Collect, because it concisely expresses the character of each celebration, indicates for us these unique graces” (Father Stice, ‘The Grand Outlines of the Spiritual Universe: Praying the Collects of the Roman Rite’).
‘O God, who cause the minds of the faithful to unite in a single purpose…grant that our hearts may be fixed on that place where true gladness is found…’ (Collect of the 21st Sunday).

We are then prepared to hear the Word of the Lord, in the Liturgy of the Word.