It stands to reason that the priest should make a personal preparation before celebrating Mass. Originally this preparation must have been wholly made in the sacristy, as the Mass commenced immediately with the reading of the Epistle (No. 144). The processions and litanies which were introduced after the fourth century supplied a place for the preparation in the church itself. As the choir was singing the Introit and the Kyrie the priest had time for private prayers, and this time he utilized in preparing for Mass. When we remember that the Mass is the same Sacrifice as that of the Cross, and that the bread and wine become the very Body and Blood of Christ, we can understand the words of the Imitation, "If thou hadst the purity of an angel, and the sanctity of Saint John the Baptist, thou wouldst not be worthy to receive or handle the Sacrament." The priest who approaches the altar is convinced of this truth, and therefore he bows down before God and confesses that he is a sinner. This confession of sin was made formerly on the way into the church. It consisted of three parts, the first of which was said on the way to the altar, the second at the foot of the altar, and the third as the priest went up the steps of the altar. The prayer said on the way to the altar was derived from a custom practiced in the earliest ages by the newly baptized (No. 74). They went from the baptistry into the church reciting the verse from the psalm, "I will go unto the altar of God, unto God who gladdeneth my youth." Saint Peter called the converts "new-born babes," and after their baptism their youth was renewed in Christ. When the priest was about to celebrate Mass he adopted the same exclamation, "I will go unto the altar of God, unto God who gladdeneth my youth." The prayers said at the foot of the altar consisted of an acknowledgment of sin, and the prayers said as the priest mounted the steps asked God for forgiveness. The whole preparation therefore may be known as the "Confession."
The Christians were accustomed to begin all their actions with the Sign of the Cross (No. 34). Consequently the preparation of the priest begins with that ceremony. Sometimes the Sign of the Cross is accompanied by a special form of words called the Invocation. It runs as follows: "In the name of the Father and of the Son and of the Holy Ghost, Amen," and is a profession of faith in the Holy Trinity. This form was used by the priest as he set forth to begin the Mass. On the way to the altar he recited the verse, "I will go unto the altar of God." In some places the priest was accustomed to say the forty-second Psalm, from which this verse was taken. He repeated it with the ministers antiphonally (No. 194). It therefore had the same structure as the Introit. The verse, "I will go unto the altar of God," was used as the anthem. Then followed the psalm and the lesser Doxology, with the anthem repeated. As the psalm begins, "Judge me, God," or in Latin, "Judica me Deus," it is commonly referred to as the "Judica." The use of the Judica was not made obligatory until the Missal of Pius V, in the sixteenth century, when it was ordered that the Invocation and Psalm should be said, not as heretofore on the way to the altar, but at the foot of the altar. The Carmelites, who claimed a two hundred years use for the old method of saying it, still retain that custom, and the Dominicans, who invoked the same time limit for another psalm, disregard it altogether. Even in the Roman Missal the Judica is omitted at Masses for the dead and at the Masses at Passiontide (No. 191). The Church keeps the additions to her Liturgy for festival occasions. In seasons of sorrow and penance she naturally reverts to the ancient and unadorned type, just as people who are glad and who rejoice, dress themselves in their best, but when they mourn they use clothes of sober colors and of simple cut.
The confession of sins is a public acknowledgment of sinfulness. The priest makes this acknowledgment before God, the saints and the attendant ministers. As the declaration opens with the word, "Confiteor" (I confess), it is called the "Confiteor." Before the introduction of the Judica, with its foregoing invitation, the Confitear was the beginning of the priest's preparation. Accordingly, he signs himself with the cross before saying it, using the words. "Our help is in the name of the Lord," to show that all help and grace come to us through the cross of Christ. The Confiteor is said by the priest first, and the ministers reply in a short prayer asking God to have mercy. Then they repeat the Confiteor, and the priest answers in the same prayer for mercy. The form of these prayers, as we have them now, was first fixed in the sixteenth century by the Missal of Pius V; but, as their introduction dates from the eleventh century, the Dominicans use a different form, but the meaning of both is the same.
The official declaration that sins are forgiven is called "Absolution," or loosing from sin. The declaration may either take the form of a positive statement, "I loose thee," or "Thou art absolved," or it may take the form of a petition, "May God loose thee," or "May God for give thee." In the Roman Liturgy the first form is used in the Sacrament of Penance when accusation of particular sins is made. The second form is used where there is a general accusation of sin outside of the Sacrament of Penance. Therefore, the absolution which the priest pronounces after the Confiteor has the form of a prayer. He follows it with certain versicles and prayers whose burden still is the cry for mercy. The prayers are said as he goes up the steps to the Holy of Holies (No. 69), and as he kisses the altar where the relics of the saints are laid, and may be called the "Prayers of Access." This third part, like the two preceding parts, is begun by the Sign of the Cross, which is made while the absolution is given.
As the new Introduction to the Mass grew out of a procession we find that incense is used thereat (No. 180). When the priest has finished the confession and reached the altar, he blesses the incense with the words, "Be thou blessed by Him in whose honor thou shalt be burned." Then he takes the censer and swings it three times towards the Cross (No. 85), as a mark of respect, and afterwards perfumes the whole altar, passing and re-passing the censer over the table, by the sides and along the front. Finally, he is himself saluted by the deacon, who swings the censer towards him, both as a mark of respect and as an invitation to prayer. In Low Masses this ceremony is omitted for the reasons given in No. 191.
The Introit Psalm was sung while the ministers and people entered the church. When those processions were large, there was sufficient time to go through a whole psalm. But when the procession was reduced to the mere entrance of the ministers (No. 186), the time was much shortened, and the Bishop stopped the singing of the psalm when all the ministers were in their places. In this way it came to pass that only a single verse of the Introit Psalm was sung, and our modern Introits are constructed on this principle:
• Antiphon.
• One verse of Psalm.
• Gloria.
• Antiphon
As the Introit was once the beginning of the Mass, the priest makes the Sign of the Cross when he recites it. Moreover, for the same reason, Masses are named after the first words of the Introit, and sometimes days are named after the Masses. Thus a "Requiem Mass" has an Introit beginning "Requiem Aeternam," or "Eternal Rest." The fourth Sunday in Lent is "Laetare Sunday" because the "Mass Laetare" is said thereon. The "Mass Laetare" gets its name from the Antiphon to the Introit, "Laetare, Jerusalem," or "Rejoice, O Jerusalem." The Sunday after Easter is known as Low Sunday, or "Quasimodo," because the Mass begins with these words: "Quasimodo geniti infantes," "as new-born babes." With regard to the construction of the Introit it may be well to note that at Requiem Masses and during Passiontide the "Gloria Patri" is omitted.
The ancient Litany is represented by the Kyrie eleison (No. 173). At present this Litany is sung by the choir and also recited alternately by the priest and ministers. It consists of "Kyrie eleison" repeated thrice, followed by "Christe eleison," or "Christ, have mercy," said the same number of times, and closed by the threefold Kyrie again. This Litany also represents the answers made by the people to the prayers derived from the Egyptian Hallel. In the Roman Liturgy those prayers were nine in number, as we may see from the Mass on Good Friday. Those nine responses were divided into groups of three, one directed to the Father, one to the Son and one to the Holy Ghost.
When our Lord was born in Bethlehem, the shepherds heard the angels singing, "Glory be to God on high and on earth peace to men of good will." In the first half of the second century Pope Telesphorus ordered that this hymn should be sung on Christmas Day before the Mass. As the Mass then began with the Epistle, the hymn was recited immediately before it By the sixth century this practice had extended to other feasts, when the Mass was celebrated by a Bishop. Priests were permitted to use it only on Easter Day. During the middle ages this distinction disappeared, and now the hymn is sung on all feast days, and on all Sundays except those which occur in Advent and between Septuagesima and Holy Week. From the Latin words, "Glory be to God on high" ("Gloria in Excelsis"), it is known as the "Gloria in Excelsis," or, briefly, the "Gloria." It is also called the Angels Hymn and the Greater Doxology (No. 194). When the prayers (No. 186) were transferred to the beginning of the Mass, they came between the Gloria and the Epistle; consequently, it is now recited between the Kyrie and the Collect. In course of centuries several clauses were added to the original words. The text in the Roman Missal is as follows:
"Glory be to God on high, and on earth peace to men of good will.
"We praise Thee. We bless Thee. We worship Thee. We glorify Thee. We give Thee thanks for Thy great glory.
"O Lord God, heavenly King, God the Father Almighty.
"O Lord, the only begotten Son, Jesus Christ. Lord God, Lamb of God, Son of the Father.
"Thou that takest away the sins of the world, have mercy upon us. Thou that takest away the sins of the world, receive our prayers. Thou that sittest at the right hand of the Father, have mercy upon us.
"For Thou only art holy. Thou only art the Lord. Thou only art most high, Jesus Christ. With the Holy Ghost, in the glory of God the Father. Amen."
- taken from The Mass, by Father Peter Christopher Yorke