An excerpt from Pope Pius XII's "Mediator Dei"
in which he explains how we of the royal priesthood should approach the Most Holy Sacrifice of the Mass:
91. But there is also a more profound reason why all Christians, especially those who are present at Mass, are said to offer the sacrifice.
92. In this most important subject it is necessary, in order to avoid giving rise to a dangerous error, that we define the exact meaning of the word "offer." The unbloody immolation at the words of consecration, when Christ is made present upon the Altar in the state of a victim, is performed by the priest and by him alone, as the representative of Christ and not as the representative of the faithful. But it is because the priest places the divine victim upon the Altar that he offers it to God the Father as an oblation for the glory of the Blessed Trinity and for the good of the whole Church. Now the faithful participate in the oblation, understood in this limited sense, after their own fashion and in a twofold manner, namely, because they not only offer the sacrifice by the hands of the priest, but also, to a certain extent, in union with him. It is by reason of this participation that the offering made by the people is also included in liturgical worship.
93. Now it is clear that the faithful offer the sacrifice by the hands of the priest from the fact that the minister at the Altar, in offering a sacrifice in the name of all His members, represents Christ, the Head of the Mystical Body. Hence the whole Church can rightly be said to offer up the victim through Christ. But the conclusion that the people offer the sacrifice with the priest himself is not based on the fact that, being members of the Church no less than the priest himself, they perform a visible liturgical rite; for this is the privilege only of the minister who has been divinely appointed to this office: rather it is based on the fact that the people unite their hearts in praise, impetration, expiation and thanksgiving with prayers or intention of the priest, even of the High Priest himself, so that in the one and same offering of the victim and according to a visible sacerdotal rite, they may be presented to God the Father. It is obviously necessary that the external sacrificial rite should, of its very nature, signify the internal worship of the heart. Now the sacrifice of the New Law signifies that supreme worship by which the principal Offerer himself, who is Christ, and, in union with Him and through Him, all the members of the Mystical Body pay God the honor and reverence that are due to Him.
94. We are very pleased to learn that this teaching, thanks to a more intense study of the liturgy on the part of many, especially in recent years, has been given full recognition. We must, however, deeply deplore certain exaggerations and over-statements which are not in agreement with the true teaching of the Church.
95. Some in fact disapprove altogether of those Masses which are offered privately and without any congregation, on the ground that they are a departure from the ancient way of offering the sacrifice; moreover, there are some who assert that priests cannot offer Mass at different Altars at the same time, because, by doing so, they separate the community of the faithful and imperil its unity; while some go so far as to hold that the people must confirm and ratify the sacrifice if it is to have its proper force and value.
96. They are mistaken in appealing in this matter to the social character of the eucharistic sacrifice, for as often as a priest repeats what the divine Redeemer did at the Last Supper, the sacrifice is really completed. Moreover, this sacrifice, necessarily and of its very nature, has always and everywhere the character of a public and social act, inasmuch as he who offers it acts in the name of Christ and of the faithful, whose Head is the divine Redeemer, and he offers it to God for the holy Catholic Church, and for the living and the dead.This is undoubtedly so, whether the faithful are present - as we desire and commend them to be in great numbers and with devotion - or are not present, since it is in no wise required that the people ratify what the sacred minister has done.
97. Still, though it is clear from what We have said that the Mass is offered in the name of Christ and of the Church and that it is not robbed of its social effects though it be celebrated by a priest without a server, nonetheless, on account of the dignity of such an august mystery, it is our earnest desire - as Mother Church has always commanded - that no priest should say Mass unless a server is at hand to answer the prayers, as canon 813 prescribes.
98. In order that the oblation by which the faithful offer the divine Victim in this sacrifice to the heavenly Father may have its full effect, it is necessary that the people add something else, namely, the offering of themselves as a victim.
99. This offering in fact is not confined merely to the liturgical sacrifice. For the Prince of the Apostles wishes us, as living stones built upon Christ, the cornerstone, to be able as "a holy priesthood, to offer up spiritual sacrifices, acceptable to God by Jesus Christ." St. Paul the Apostle addresses the following words of exhortation to Christians, without distinction of time, "I beseech you therefore, . . . that you present your bodies, a living sacrifice, holy, pleasing unto God, your reasonable service." But at that time especially when the faithful take part in the liturgical service with such piety and recollection that it can truly be said of them: "whose faith and devotion is known to Thee," it is then, with the High Priest and through Him they offer themselves as a spiritual sacrifice, that each one's faith ought to become more ready to work through charity, his piety more real and fervent, and each one should consecrate himself to the furthering of the divine glory, desiring to become as like as possible to Christ in His most grievous sufferings.
100. This we are also taught by those exhortations which the Bishop, in the Church's name, addresses to priests on the day of their ordination, "Understand what you do, imitate what you handle, and since you celebrate the mystery of the Lord's death, take good care to mortify your members with their vices and concupiscences." In almost the same manner the sacred books of the liturgy advise Christians who come to Mass to participate in the sacrifice: "At this . . . Altar let innocence be in honor, let pride be sacrificed, anger slain, impurity and every evil desire laid low, let the sacrifice of chastity be offered in place of doves and instead of the young pigeons the sacrifice of innocence." While we stand before the Altar, then, it is our duty so to transform our hearts, that every trace of sin may be completely blotted out, while whatever promotes supernatural life through Christ may be zealously fostered and strengthened even to the extent that, in union with the immaculate Victim, we become a victim acceptable to the eternal Father.
101. The prescriptions in fact of the sacred liturgy aim, by every means at their disposal, at helping the Church to bring about this most holy purpose in the most suitable manner possible. This is the object not only of readings, homilies and other sermons given by priests, as also the whole cycle of mysteries which are proposed for our commemoration in the course of the year, but it is also the purpose of vestments, of sacred rites and their external splendor. All these things aim at "enhancing the majesty of this great Sacrifice, and raising the minds of the faithful by means of these visible signs of religion and piety, to the contemplation of the sublime truths contained in this sacrifice."
102. All the elements of the liturgy, then, would have us reproduce in our hearts the likeness of the divine Redeemer through the mystery of the cross, according to the words of the Apostle of the Gentiles, "With Christ I am nailed to the cross. I live, now not I, but Christ liveth in me." Thus we become a victim, as it were, along with Christ to increase the glory of the eternal Father.
103. Let this, then, be the intention and aspiration of the faithful, when they offer up the divine Victim in the Mass. For if, as St. Augustine writes, our mystery is enacted on the Lord's table, that is Christ our Lord Himself, who is the Head and symbol of that union through which we are the body of Christ and members of His Body; if St. Robert Bellarmine teaches, according to the mind of the Doctor of Hippo, that in the sacrifice of the Altar there is signified the general sacrifice by which the whole Mystical Body of Christ, that is, all the city of redeemed, is offered up to God through Christ, the High Priest: nothing can be conceived more just or fitting than that all of us in union with our Head, who suffered for our sake, should also sacrifice ourselves to the eternal Father. For in the sacrament of the Altar, as the same St. Augustine has it, the Church is made to see that in what she offers she herself is offered.
104. Let the faithful, therefore, consider to what a high dignity they are raised by the sacrament of baptism. They should not think it enough to participate in the eucharistic sacrifice with that general intention which befits members of Christ and children of the Church, but let them further, in keeping with the spirit of the sacred liturgy, be most closely united with the High Priest and His earthly minister, at the time the consecration of the divine Victim is enacted, and at that time especially when those solemn words are pronounced, "By Him and with Him and in Him is to Thee, God the Father almighty, in the unity of the Holy Ghost, all honor and glory for ever and ever"; to these words in fact the people answer, "Amen." Nor should Christians forget to offer themselves, their cares, their sorrows, their distress and their necessities in union with their divine Savior upon the cross.