From the foreword by the late Fr. Benedict J. Groeschel CFR to Dr. Scott Hahn’s The Lamb’s Supper: The Mass as Heaven on Earth (Doubleday, 1999):
I always feel a twinge of annoyance when I see in a college or a hotel a list of “religious services” and observe the Mass listed at 9 am. The Mass is not a religious service. When Catholics say morning prayer or the recitation of the rosary or even have Benediction of the Blessed Sacrament, that’s a service. It’s something that we do for God, similar to the public prayer of any religious denomination. But the Holy Sacrifice of the Eucharist, the Divine Liturgy, is not precisely — in its essence — done by man at all.
Let me tell you, I’ve been a priest for forty years and I never conducted a “service” called a Mass. I was a “stand-in” for the High Priest, to use the words of Church teaching, I was there functioning in persona Christi — in the person of Christ, the High Priest of the Epistle to the Hebrews. People do not come to Mass to receive my body and blood, and I could not have given it to them if they did. They come for communion with Christ.
This is the mysterious element in all Christian sacraments — including baptism. For this reason, in case of great necessity anyone can function in persona Christi to give baptism, because it is Christ Who actually baptizes. It is Christ Who forgives sin, Christ Who prepares the dying, Christ Who ordains and Who blesses the marriages.
Like Catholic and Orthodox Christians who think about it (as well as some Anglicans and even some Lutherans), I believe that Christ is the Priest of all the sacraments, just as He speaks to us from every page of Sacred Scripture. He ministers to us in every sacrament — and we experience in this way the vitality of His mystical body.