What Is A Priest?
The popular definition of a priest is given as an ordained person with the authority to perform certain rites and administer certain sacraments. Properly speaking, however, a priest is one who offers sacrifice. This is what a priest is. This is what a priest does. This is who a priest is. A priest has handed over his life to be at the service of Jesus Christ and to pour himself out in His service.
Truly, there is only one Priest, the one mediator between God and man, the man Christ Jesus. Jesus is our great High Priest and every ordained man simply takes part in that one priesthood in varying degrees. For example, every baptized person shares in the priesthood of Christ in a general way. Whereas, deacons, priests, and bishops participate in the priesthood of Christ in particular and ever-greater degrees.
Priesthood of All Believers
In the general sense, we are all priests through our Baptism, because we all offer the sacrifice of our contrite hearts and our lives which take on new meaning when united with the one Sacrifice of Christ on the Cross. For our Baptism is a kind of death, a sharing in the Cross. Therefore, in the priesthood of believers, we come to share in His Resurrection.
The Ministerial and Ordained Priesthood
The priest, however, in a very particular way, acting in the person of Christ, Head of His Body, offers the one Sacrifice of Christ on Calvary. This is the essence of the Most Holy Sacrifice of the Mass. The entire Paschal Mystery of Christ becomes truly present by the power of God at every single Holy Mass.
The entrance of Christ into Jerusalem, His suffering, death, and resurrection, and His glorious ascension all become present once more. This one sacrifice is perpetuated as an everlasting memorial. Christ does not die again, yet His saving action becomes present once more through the Divine and Sacred Liturgy at the hands of the priest in the High Priesthood of Jesus Christ.
The Nature of the Sacred Liturgy
At its core, the Divine and Sacred Liturgy is the offering of the Son of God to the Father in the Spirit. In truth, this is the eternal action and the essence of God, the Most Holy Trinity. The Son pours Himself out to the Father in love. The Father returns this love perfectly, and that perfect love is the Person of the Holy Spirit.
The Holy Mass is, therefore, the action of Almighty God. The ordained minister is offering the sacrifice at his hands, but only by the High Priesthood of Jesus Christ. It is by His authority that the priest acts and speaks. This is the greatest glory of authentic Christian worship in the Catholic and orthodox Faith. No matter how lacking we are and no matter how lacking our personal sacrifice, the Most Holy Sacrifice of the Mass is the perfect prayer and perfect offering Jesus Christ to the Father in the Spirit.
Private vs. Public Mass
Every single Holy Mass is celebrated primarily by Jesus Christ. In this heavenly banquet and sacrificial meal, there are many who are already living in the perfection of the Trinity. The saints in Heaven, whether they are officially canonized or not, are taking part fully, consciously, and actively in the Holy Mass. Likewise, the angels are constantly worshipping God in accord with His desires.
When Mass is celebrated publicly, there is more than just the priest present on earth. There may be other ministers, a cantor, an altar server, a reader, or some other member(s) of the lay faithful. These Masses are beautiful because they show a greater sign of the Mystical Body of Christ gathered to worship God, head and members.
However, what if a priest has to offer Mass privately? This has happened throughout the history of the Church. Priests are encouraged to offer Mass daily and they are therefore unable to have the faithful present every time they offer Mass. This is colloquially known as a private Mass, but the name is misleading.
No Mass is private. At every single Mass, Jesus Christ is offering Himself eternally to the Father in the power and working of the Holy Spirit, and the angels and saints are actively taking part in this perfect worship. Heaven and Earth meet. The imminent and transcendent kiss. So, whether the faithful are present or not, the Holy Mass is the Holy Mass.
Efficacy and Aims of the Most Holy Sacrifice of the Mass
Since the very first Eucharist at the Last Supper, Jesus instituted the Most Holy Eucharist as the memorial of His suffering and death, by which the graces of the Cross would flow to the entire world, even two thousand years later. For, in the Mass, the Cross becomes truly present once more and the Blood of Christ flows to purify the world.
The Mass is a true sacrifice that is offered to God alone. It is a sacrifice offered for the praise and adoration of our triune God in thanksgiving. The Mass is also offered for impetration, that is, to lay our requests for the world before God. The Mass is also a propitiatory sacrifice because it is the re-presentation of the Cross. In other words, the Blood of Christ flowing from the Cross is offered in expiation for the sins of mankind.
Our High Priest, standing once again in the breach as our mediator, by the hands of the ordained priest, is offering His prayer on our behalf to God of praise, adoration, thanksgiving, propitiation, and impetration. Every single Mass is therefore infinitely efficacious and good, whether the faithful are present or not.
Therefore, Mass is never really private. It is always crowded. We just do not yet have eyes to see this glorious reality.