Browsing Augustine’s City of God I chanced upon the text of the prophecy of the Erythraean sibyl, which is alluded to in the famous fragment Dies irae.
Dies irae, dies illa
Solvet saeclum in favilla
Teste David cum Sibylla.
Ι Judgment shall moisten the earth with the sweat of its standard,
Η Ever enduring, behold the King shall come through the ages,
Σ Sent to be here in the flesh, and Judge at the last of the world.
Ο O God, the believing and faithless alike shall behold Thee
Υ Uplifted with saints, when at last the ages are ended.
Σ Seated before Him are souls in the flesh for His judgment.
Χ Hid in thick vapors, the while desolate lieth the earth.
Ρ Rejected by men are the idols and long hidden treasures;
Ε Earth is consumed by the fire, and it searcheth the ocean and heaven;
Ι Issuing forth, it destroyeth the terrible portals of hell.
Σ Saints in their body and soul freedom and light shall inherit:
Τ Those who are guilty shall burn in fire and brimstone for ever.
Ο Occult actions revealing, each one shall publish his secrets;
Σ Secrets of every man’s heart God shall reveal in the light.
Θ Then shall be weeping and wailing, yea, and gnashing of teeth;
Ε Eclipsed is the sun, and silenced the stars in their chorus.
Ο Over and gone is the splendor of moonlight, melted the heaven,
Υ Uplifted by Him are the valleys, and east down the mountains.
Υ Utterly gone among men are distinctions of lofty and lowly.
Ι Into the plains rush the hills, the skies and oceans are mingled.
Ο Oh, what an end of all things! earth broken in pieces shall perish;
Σ Swelling together at once shall the waters and flames flow in rivers.
Σ Sounding the archangel’s trumpet shall peal down from heaven,
Ω Over the wicked who groan in their guilt and their manifold sorrows.
Τ Trembling, the earth shall be opened, revealing chaos and hell.
Η Every king before God shall stand in that day to be judged.
Ρ Rivers of fire and brimstone shall fall from the heavens.
 The Nicene and Post-Nicene Fathers Vol. II. St. Augustin’s City of God and Christian Doctrine, p. 372.