The Catechism of the Summa - Tertia Pars - XXXVI. OF THE HOLY SACRIFICE OF THE MASS

What is meant by the celebration of the sacrament of the Holy Eucharist or of the Holy Sacrifice of the Mass?

It means that the act whereby this sacrament is confected constitutes a veritable sacrifice in the sense that it is an immolation according to the rite existing in the Catholic Church (LXXXIII. 1).

In what does this act consist?

In an immolation of the only Victim that is pleasing to God, namely of Jesus Christ Himself.

How is this act an immolation of Jesus Christ?

Because it is the sacrament of the Passion by which Jesus Christ was immolated on Calvary (LXXXII. 1).

What is meant by saying this?

By this is meant that just as on Calvary at the moment when Jesus Christ gave His life for the expiation of our sins His Body and His Blood were separated, so the act by which this sacrament is confected separates sacramentally the Body of Jesus Christ from His Blood; and this by the fact that there is a separate consecration for the species of bread and a separate consecration for the species of wine.

What follows from this?

It follows that the sacrifice of the Mass is the same as the sacrifice on the cross.

Is it a reproduction of the sacrifice on the cross?

Properly speaking, no; because the sacrifice of the cross took place only once; on the other hand, the Mass is not a reproduction of this sacrifice, it is the sacrifice itself.

May one say it is a representation of the sacrifice on the cross?

Yes, if by this one means that the Mass makes that sacrifice present for us; but it would be incorrect if one meant to say that it was only an image or a likeness thereof, for it is the sacrifice itself.

But how can it be the sacrifice itself since that sacrifice exists no longer, and, further, in the sacrifice on the cross Christ died, whereas now He can die no more?

In this sacrament there is truly the sacrifice on the cross as there is Jesus Christ Himself. For just as Jesus Christ is here present in Himself but under another form, since He is here under the species of the sacrament, in the same way the Passion and the immolation of Jesus Christ which took place on Calvary is here, not indeed under the same violent form but under the form of a sacrament: in such wise that under this sacrament there is in the same state of separation, which constitutes the immolation of the Victim, the same Body and the same Blood of Jesus Christ which were really separated on Calvary.

When one assists at the celebration of this sacrament, is it as if one assisted at the immolation of Jesus Christ on Calvary?

Yes; and we cannot perform an act of religion more pleasing to God, since it honours and glorifies Him above all else.

Is it for this reason that the Church desires we should assist as often as possible at the Holy Sacrifice of the Mass?

Yes; and the Church has even determined that on Sundays and certain feast days it is obligatory to hear mass (Code, Canon 1248).

Does one sin gravely unless one attends Mass on these days fixed by the Church?

Yes; unless one is absolutely impeded from being present.

What must one do in order to fulfil the obligation of assisting at Mass on the days aforementioned?

One must be present in the place where it is celebrated, and one must not do anything which is incompatible with so august a sacrifice; moreover, one must not be absent from its principal parts.

What are these principal parts of the Mass?

They come between the offertory and the communion inclusively.

What is the best way to hear Mass?

It is to be united with the priest, following him from part to part so as to pay attention to all that is said and done during the Mass.

Next - The Catechism of the Summa - Tertia Pars - XXXVII. OF THE SACRAMENT OF PENANCE: OF ITS NATURE AND VIRTUE (A)