A rhymed Latin poem (attributed to Thomas of Celano) about the Day of Judgment, according to the Christian view of the apocalypse. It describes how God will return, destroy the world as we know it, and judge everyone who has ever lived severely. The poem emphasizes the pains of hell and the severity of the judgment quite dramatically, and ends by pleading for mercy from Jesus.

The poem forms the bulk (sequentia) of the standard Requiem Mass.