1. To ADORE God as our Creator.
The Mass is the ONLY worthy gift we can offer God; in it we offer to Him His own Son. Having a perfect sacrifice in the Mass, Christians need, and have, no other sacrifice to offer to God but this one.
2. To THANK God for His many favors.
In the Mass Jesus Christ the Son of God speaks for us to His eternal Father; we have an advocate with Him. Can we fail but speak well, having this instrument of thanksgiving?
3. To ASK God to bestow His blessings on all men.
Holy Mass may be offered for the living of whatever creed. It may be offered for departed Catholics. The priest may not offer Mass publicly for departed non-Catholics, but the persons hearing the Mass may do so. Persons hearing Mass may have their own private intentions for offering it, aside from the intention of the priest. Mass may be offered for any intention except that which is in itself bad.
4. To SATISFY the justice of God for the sins committed against Him.
The Mass reconciles man with God, as we learn from the words of Christ uttered at the Last Supper, “This is my blood, which is being shed for many unto the forgiveness of sins” (Matthew 26:28). We are not redeemed all over again by the Mass, for we were redeemed once on the cross; but the Mass applies to our souls the fruits of redemption gained for us on the cross. As a perfect propitiatory sacrifice, the Mass satisfies the justice of God.
Holy Mass may be offered to God with a fourfold intention: by way of adoration, thanksgiving, petition, and atonement. It is for the spiritual and temporal welfare of the living, and for the eternal repose of the dead. Every day of the year Holy Mass is offered, except Good Friday and Holy Saturday.
There are different kinds of Masses: (a) low Mass, read or recited by the priest; (b) high Mass, sung by priest and choir; and (c) solemn high Mass, with deacon and subdeacon assisting the celebrant. These are not really different; they differ only in the elaborateness of the ceremonies used. A pontifical Mass is a high Mass said by a bishop. A bishop puts on his vestments and takes them off before the altar, unlike the priest, who vests himself in the sacristy. Above is a pontifical Mass.