The Mass is made of two main parts:
Mass begins with the entrance of the Priest. On Sundays and Feast Days, an entrance hymn will be sung. Otherwise, a short passage (usually from Scripture) is recited called the "Entrance Antiphon".
Being our greatest prayer, the Mass begins by making the Sign of the Cross (the traditional way that Catholics "bless themselves" and begin and conclude "formal" prayers).
The Priest greets the people and invites everyone to reflect briefly on their unworthiness and sinfulness to prepare for the celebration of the Mass. The People may recite the "Confiteor":
I confess to Almighty God,
and to you here present,
that I have sinned through my own fault,
["mea culpa, mea culpa, mea maxima culpa"]
in my thoughts and in my words,
in what I have done and in what I have failed to do.
And I ask Blessed Mary, ever Virgin,
all the Angels and Saints,
and you here present
to pray for me to the Lord, our God.
The Priest then leads the "Kyrie" -- "Lord have mercy", "Christ have mercy", "Lord have mercy" -- before giving a general absolution to prepare the People for reception of the Blessed Sacrament. (This does not apply to people in a state of Mortal Sin who must first receive absolution within the Sacrament of Penance before approaching the Blessed Sacrament.)
There is an then an opening prayer recited by the Priest. The prayers and the various readings chosen for the particular Mass follow a particular "theme".
First, a passage from the Old Testament, the Acts of the Apostles or the Book of Revelation is read.
This is followed either by the singing or recitation of one of the Psalms. Usually a lector or cantor will recite or sing a verse, to which the People will respond with an antiphon from the Psalm.
Then, a passage from one of the Epistles (the New Testament "Letters") is read as the Second Reading.
At feria (weekday) Masses, only one reading and Psalm occurs. At some Masses, additional readings are also given -- at the Easter Vigil, the most important Mass of the year, celebrating the Resurrection, there can be up to 15 readings!
The First and Second Readings and Psalm are usually read by lay people, most properly by Lectors, lay people who have been formally commissioned to read the Readings in their parish.
The Readings are then followed by the Gospel Acclamation -- a great "Alleluia!" by the People welcoming the Word. The People stand for the Gospel Acclamation and remain standing while a Priest or Deacon reads a passage from the Gospel. On particularly special occasions, the Priest may chant the Gospel.
At the conclusion of the Gospel, the People sit to listen to the Priest's "Homily", a reflection on the various readings and their application to our lives.
Following the homily and a short time to reflect quietly on what Father has said, the People stand to rectie the Creed. Catholics, as do all Christians, recite together this formulation of our Faith.
Following the Creed, the People place the needs of the world before our Father in Heaven in the "General Intercessions" or "Prayers of the Faithful". A Lector will usually read a short intercession which the People make their own by responding, "Lord, Hear our Prayer". These prayers usually pray for the Pope and the Church, the Leaders of our Nation, for an increase in vocations to the priesthood, for those in difficulties, for the sick and infirm (especially those from the particular parish), for the dead.
This concludes the first part of the Mass.
Some members of the congregation (quite often children or a family) then take up the "gifts": the candles that will sit on the altar to signal the presence of Christ, our Light, the bread which will beome the Body of Christ and the Wine which will become His Blood.
This is also when the first Collection is taken. The People are invited to give an offering which is forwarded to the Bishop or Archbishop to be used for the purposes of the Diocese.
The Priest receives these gifts and says a blessing over them, offering them to God, the work and fruit of our hands, highlighting the great mystery that God will take food and drink we have made and transform them into a Heavenly Meal, the Body and Blood of Our Lord Jesus.
After blessing the gifts, the Priest prays that God will cleanse him of all iniquity and symbolically washes his fingers which will touch the Lord.
The People then pray that God will accept the Priest's Sacrifice "for the Praise and Glory of His Name, for our good and the good of all His Church".
The Mass has its beginning in the Last Supper when Our Lord first changed bread and wine into His Body and Blood. But it also has its links in the great events of Good Friday. Each Mass is a continuation and a re-offering of Christ's sacrifice on Calvary. It takes the holocausts and burnt, bloody sacrifices of the Old Testament and transforms them into the Holy Sacrifice of the Lamb of God that redeemed all mankind.
After the Priest recites a short prayer of praise to God -- the "Preface" -- the People sing the Heavenly Chant of the "Sanctus" "with all the Angels and Saints":
Holy, Holy, Holy Lord,
God of Power and Might,
Heaven and Earth are full of Your glory
Hosanna in the Highest!
Blessed is He who comes in the name of the Lord
Hosanna in the Highest!
The People then kneel in readiness for the moment when Jesus will become truly, physcically present on the altar.
The Priest begins to pray a great prayer of thanksgiving and supplication to God called the "Eucharistic Prayer". There are a number of Eucharistic Prayers for the Priest to choose from:
The common elements of the Eucharistic Prayers are:
This is my Body (hic est enim corpus meum)
This is the cup of my Blood (hoc est calix sanguinis meus)
Through Him, with Him, in Him, in the unity of the Holy Spirit, all glory and honour are Yours, Almighty Father, for ever and ever. Amen.
The People then stand to say the Lord's Prayer together and to share the Kiss of Peace with each other (usually a handshake or a nod of the head!)
The Priest then breaks the Body of Christ while the People pray, "Lamb of God, who takes away the sins of the world, have mercy on us." (Agnus Dei, qui tollis peccata mundi, miserere nobis).
The Priest then invites us again to acknowledge our unworthiness in the "Domine, non sum dignus":
"Lord, I am not worthy to receive you but only say the word, and I shall be healed."
The Priest then eats and drinks the Body and Blood of the Lord before proceeding to distribute the Sacrament to each of the People in turn who wish and are able to receive communion.
This is the great pinnacle of the Mass, of the Christian Life, of the Church, the moment when Jesus, truly present, Body, Blood, Soul and Divinity, enters into our very being, our bodies and souls, making us one together with Him and with each other, cleaving us to His Mystical Body, the Church.
Needless to say, a few moments' quiet refletion and then a song of great joy and praise follow this blessed moment!
At this stage, a second collection is usually taken. The proceeds of this collection are for the needs of the parish (maintenance of the Church buildings, paying for the electricity, funds for the Parish School, etc.) and to provide for the priests.
After consuming any remaining Precious Blood and placing any remaining hosts in the Tabernacle, the Priest cleans and purifies the sacred vessels and then sits quietly for a time in reflection and thanksgiving.
Finally, the Priest blesses the People and "dismisses" them "The Mass is ended! Go in Peace to love and serve the Lord!" He sends us out into the World to take Christ with us in our hearts and make Him known to whoever we meet. The Priest then proceeds out of the Church while the People sing a final hymn.