Today is a day where the Mass and its texts teach us a lot. The Requiem Mass is one of the most sublime and haunting amalgamation of texts and chants ever heard. Some of the polyphonic and orchestral settings for today's Mass—especially Mozart's—can thunder over you, but nothing quite does the job on the Inroit or Dies Irae like plainsong.
Day of wrath, that day
When the world will dissolve in ashes burning
As told by David and Sybil
Later the great hymn focuses on the deceased, probably a later addition:
How tearful that day will be!
When the man to be judged
Rises from ashes
Therefore, spare him, oh God!
Sweet Lord Jesus!
Grant them eternal rest. Amen
After the Last Gospel the priest and his ministers go to the catafalque—a pseudo-coffin made to recall the souls of purgatory present at Mass who require prayers of aid. The priest sprinkles it with holy water and incenses it whilst saying the Pater noster. The great Libera Nos is sung. At the end there are a few short prayers. Here is one such instance from Rome:
Libera nos, Domine, de morte aeterna, in die illa tremenda: * Quando coeli movendi sunt et terra: * Dum veneris judicare saeculum per ignem.—Libera nos from the absolution
Deliver me, O Lord, from death eternal in that awful day. * When the heavens and the earth shall be moved: * When Thou shalt come to judge the world by fire.—translation of above