Catechism of St. Pius X
The Essence, Institution and Ends of the Holy Sacrifice of the Mass
1. Should the Holy Eucharist be considered only as a sacrament?
The Holy Eucharist, besides being a sacrament, is also the permanent Sacrifice of the New Law, which Jesus Christ left to His Church to be offered to God by the hands of His priests.
2. What is the Holy Mass?
The Holy Mass is the Sacrifice of the Body and Blood of Jesus Christ offered on our altars under the appearances of bread and wine, in commemoration of the Sacrifice of the Cross.
3. Is the Sacrifice of the Mass the same as that of the Cross?
The Sacrifice of the Mass is substantially the same as that of the Cross, for the same Jesus Christ, Who offered Himself on the Cross, it is Who offers Himself by the hands of the priests, His ministers, on our altars; but as regards the way in which He is offered, the Sacrifice of the Mass differs from the Sacrifice of the Cross, though retaining the most intimate and essential relation to it.
4. What difference and relation is there between the Sacrifice of the Mass and that of the Cross?
Between the Sacrifice of the Mass and that of the Cross there is this difference and relation, that on the Cross Jesus Christ offered Himself by shedding His Blood and meriting for us; whereas on our altars He sacrifices Himself without the shedding of His Blood, and applies to us the fruits of His passion and death.
5. What other relation has the Sacrifice of the Mass to that of the Cross?
Another relation of the Sacrifice of the Mass to that of the Cross is, that the Sacrifice of the Mass represents in a sensible way the shedding of the Blood of Jesus Christ on the Cross, because, in virtue of the words of consecration, only the Body of our Saviour is made present under the species of the bread and only His Blood under the species of the wine; although by natural concomitance and by the hypostatic union, the living and real Jesus Christ is present under each of the species.
6. Is not the Sacrifice of the Cross the one only Sacrifice of the New Law?
The Sacrifice of the Cross is the one only Sacrifice of the New Law, inasmuch as through it Our Lord satisfied Divine Justice, acquired all the merits necessary to save us, and thus, on His part, fully accomplished our redemption. These merits, however, He applies to us through the means instituted by Him in His Church, among which is the Holy Sacrifice of the Mass.
7. For what ends is the Holy Sacrifice of the Mass offered?
The Sacrifice of the Mass is offered to God for four ends: (1) To honour Him properly, and hence it is called Latreutical; (2) To thank Him for His favours, and hence it is called Eucharistical; (3) To appease Him, make Him due satisfaction for our sins, and to help the souls in Purgatory, and hence it is called Propitiatory; (4) To obtain all the graces necessary for us, and hence it is called Impetratory.
8. Who is it that offers to God the Sacrifice of the Holy Mass?
The first and principal Offeror of the Sacrifice of the Holy Mass is Jesus Christ, while the priest is the minister who in the Name of Jesus Christ offers the same Sacrifice to the Eternal Father.
9. Who instituted the Sacrifice of the Holy Mass?
Jesus Christ Himself instituted the Sacrifice of the Holy Mass when He instituted the Sacrament of the Blessed Eucharist and said that this should be done in memory of His passion.
10. To whom is the Holy Mass offered?
The Holy Mass is offered to God alone.
11. If the Holy Mass is offered to God alone why are so many Masses celebrated in honour of the Blessed Virgin and the Saints?
Mass celebrated in honour of the Blessed Virgin and the Saints is always a sacrifice offered to God alone; it is said to be celebrated in honour of the Blessed Virgin and the Saints to thank God for the gifts He has given them, and through their intercession to obtain from Him more abundantly the graces of which we have need.
12. Who shares in the fruits of the Mass?
The entire Church shares in the fruits of the Mass, but more particularly: (1) The priest and those who assist at Mass, the latter being united with the priest; (2) Those for whom the Mass is applied, both living and dead.
The Way to Assist at Mass
13. What is required in order to assist at Holy Mass well and profitably?
To assist at Holy Mass well and profitably two things are necessary: (1) Modesty of person and (2) Devotion of heart.
14. In what does modesty of person consist?
Modesty of person consists especially in being modestly dressed and in observing silence and recollection.
15. In hearing Holy Mass which is the best way to practise true devotion?
In hearing Holy Mass the best way to practise true devotion is the following: (1) From the very beginning to unite our intention with that of the priest, offering the Holy Sacrifice to God for the ends for which it was instituted. (2) To accompany the priest in each prayer and action of the Sacrifice. (3) To meditate on the passion and death of Jesus Christ and to heartily detest our sins, which have been the cause of them. (4) To go to Communion.