Second Part. On the Eucharist as Sacrifice

346. The Eucharist has not only the character of a Sacrament, but also of a Sacrifice. Concerning this matter the Roman Catechism, On the Eucharist, n. 71: But these two characters differ very greatly from one another. For the Sacrament is perfected by consecration; but the whole force of Sacrifice is in this, that it be offered. Wherefore, while the sacred Host is contained in the pyx or carried to the sick, it has the character of a Sacrament, not of a Sacrifice.

Then also, insofar as it is a Sacrament, it brings to those who receive the divine Host a cause of merit and all those benefits which were commemorated above. But insofar as it is a Sacrifice, it contains not only the efficacy of meriting, but also of making satisfaction; for as Christ the Lord in His Passion merited and made satisfaction for us, so those who offer this Sacrifice, whereby they communicate with us, merit the fruits of the Lord's Passion and make satisfaction.

The Eucharist, as a Sacrifice, is called Mass from the verb to send, because Christ there is the Victim sent by God; or, according to others, because at the end of the Sacrifice the people are dismissed, the Priest or Deacon saying: Go, the Mass is ended.

We must treat: 1. of the nature and efficacy of the Sacrifice of the Mass; 2. of the application of the Sacrifice of the Mass; 3. of the obligation of celebrating Mass; 4. of the time and place of celebration; 5. of the manner of celebrating.