What is dies irae?

Dies Irae literally means day of wrath. The mediaeval Christians were preoccupied with the end of the world; they anticipated the Last Judgement, followed by the millennium. After the fall of the Roman Empire there was a revival of the belief. The year 1000 excited mythological speculation, as did famines, plagues and earthquakes. The visionary Joachim of Fiore divided history into several ages and said that 1260 would be the fulfilment of the Age of the Spirit, which had begun with St. Benedict, when mankind could expect the last days of wrath. This myth, written down at the behest of the Papacy, exerted a potent influence on mediaeval thought, and in its vision of a world where the Holy Roman Empire and the Church of Rome would give place to a community of perfected beings who have no need of clergy or sacraments, it anticipated modern millennial theories.