The act par excellence of priestly charity is a Mass well said.

I am currently reading Christ - The Ideal of Priest by Blessed Columba Marmion (available from Ignatius Press and Amazon). It is a truly rich book of spirituality and theology for a priest. But all Christian faithful would benefit greatly from its wisdom. In my reading this morning I read the following:

We must remember that the act par excellence of priestly charity is a Mass well said. When he is celebrating, the priest must not think of himself alone. He bears in his heart the responsibility of his charge of souls. He must pray for his flock, for his works; for his parish, for his diocese, for the whole Church and, from the chalice of benediction which he consecrates, he will pour out on souls, even those far distant, a flood of merciful grace. On Calvary, Jesus took upon Himself our anguish and our sufferings. he was the Good Shepherd Who gave His live for all His sheep.

At the altar, when he is offering the chalice, the minister of Christ, associated by Him in His work of salvation, must embrace in a great movement of charity the divers needs of the whole human race: Offerimus tibi, Domine, calicem ... ut pro nostra et totius mundi salute, cum odore suavitatis ascendat: "We offer unto Thee, O Lord, the chalice ... for our salvation and for that of the whole world, rising with a pleasing fragrance."

This was the final paragraph in a section on the various ways a priest must exercise charity in imitation of Christ. A Mass well said is no substitute for all the other ways of living charity that are necessary for a holy life, particularly a priestly life. But it is surely the crowning of all the priest's life of charity.

As for text of the Mass quoted above, it is of course from the Offertory prayers of the Extraordinary Form of the Mass. Here is the prayer in full with English translation, and the corresponding prayer in the Ordinary Form of the Mass. I'm afraid the newer is poorer, in my opinion.

The older:

Offérimus tibi, Dómine, cálicem salutáris, tuam deprecántes cleméntiam: ut in conspéctu divínæ majestátis tuæ, pro nostra et totíus mundi salute, cum odóre suavitátis ascéndat. Amen.

We offer unto Thee, O Lord, the chalice of salvation, beseeching Thy clemency, that it may ascend in the sight of Thy divine majesty with a sweet savour, for our own salvation and for that of the whole world. Amen.

And the new (in English only):

Blessed are you, Lord God of all creation, for through your goodness we have received the wine we offer you: fruit of the vine and work of human hands, it will bcome our spiritual drink.