Both the text and the music from the Dies iræ are thought to proceed from a fragment of the responsory Libera me, Domine, although in turn, the text is linked to some verses by the prophet Sophonies, describing the Day of Judgement (So I. 15-16). Those verses are related to one of the stanzas of the Versus de die iudicii, whose author must have taken them from the biblical prophet. The Dies iræ contains the only mention of the figure of the Sibyl in all post-Trent Christian liturgy, a brief allusion to the eschatological verses of the Sibyl Eritrea, whose prophetic testimony Celano coupled with Psalm 18th by King David. The mention is found in the first verse, in which echoes of the melody Libera me Domine can be heard: “Dies iræ, dies illa, solvet sæclum in favilla: Teste David cum Sibylla” (Day of wrath! That day! Time fades into ash, according to the testimony of David and the Sibyl).

The history of the Sibyl

The history of how the pagan figure of the Sibyl Eritrea managed to make space for itself in the Christian universe is very curtous. In ancient Greece the name “sibyl” was applied to a series of feminine characters whose main role was to foretell the future using natural phenomena. Although it seems the first was from Eritrea, they grew rapidly in number, their reputation spreading until the period of the Roman Empire. Legend states that on a certain occasion the Cumaen Sibyl offered Tarquinus Superbus, the last king of Rome (534-510 AD), some books containing the prophecies of the Eritrean Sibyl. Although the monarch initially rejected them, in the end he took the books to Rome and deposited them in the Capitol. They remained there until they were destroyed by a fire in 81 AD. Years later they were partially recovered, but ultimately the emperor Honorius (395-423) ordered their destruction.