Mea culpa and non sum dignus

The Confiteor: mea culpa

In the current Missal the Confiteor is one option for the penitential act at the start of Mass, said by everyone:

It goes on: Ideo precor beatam Mariam semper Virginem, omnes Angelos et Sanctos, et vos, fratres, orare pro me ad Dominum Deum nostrum, therefore I ask blessed Mary ever Virgin, all the Angels and Saints, and you, brothers, to pray for me to the Lord our God.

• Datives after Confiteor: Deo is the person told.
• Ablatives of means: cogitatione, verbo, opere, by thought, word and deed.
• Culpa is an ablative of cause: through my fault. Maxima is the superlative of magnus, so the third one grows.

The 1962 Confiteor

In the 1962 Missal the Confiteor is said twice: first by the priest, then by the server (or the people, at a dialogue Mass). Their form names more saints and lacks et omissione:

Confiteor Deo omnipotenti, beatae Mariae semper Virgini, beato Michaeli Archangelo, beato Ioanni Baptistae, sanctis Apostolis Petro et Paulo, omnibus Sanctis, et tibi, pater: quia peccavi nimis cogitatione, verbo et opere: mea culpa, mea culpa, mea maxima culpa.

I confess to God almighty, to blessed Mary ever Virgin, to blessed Michael the Archangel, to blessed John the Baptist, to the holy Apostles Peter and Paul, to all the Saints, and to you, father: that I have sinned greatly in thought, word and deed: through my fault, through my fault, through my greatest fault.

Every name is dative, English "to":

Before the server's Confiteor, he answers the priest's with the Misereatur:

• Misereatur tui omnipotens Deus, et, dimissis peccatis tuis, perducat te ad vitam aeternam. - May almighty God have mercy on you and, your sins forgiven, bring you to eternal life.

Misereatur and perducat are subjunctives, "may he"; tui is genitive, as misereor takes one; dimissis peccatis tuis is an ablative absolute, your sins having been forgiven.

Domine, non sum dignus

Said before communion: once in the current Missal; three times in the 1962 Missal, with a strike on the breast each time.

It is the centurion's line in Matthew 8:8, with puer meus, my servant, changed to anima mea, my soul.

• Dignus plus an ablative. Worthy of a thing takes a plain ablative: dignus laude, worthy of praise.
• Worthy that something happen takes a subjunctive clause: ut intres, from intro. Classical prose prefers dignus qui; dignus ut is later Latin, as in the Vulgate.
• Sub with the accusative. Sub tectum is movement in under the roof; sub tecto would be simply under it.
• Dic verbo. Verbo is an ablative of means: say it by a word.