This is one of my favourite hymns, known as Day of Wrath in English. It is an Advent hymn, but has been used for requiems and All Souls Day also. It is about the Final Judgment of the saved and the damned. http://m.youtube.com/watch?v=Dlr90NLDp-0
I adore Gregorian Chant. This is a fine piece regarding the Last Judgement, a subject that sadly is often glossed over in contemporary churches (particularly Evangelicalism, I am not criticizing Evangelicals, just pointing out The Last Judgement is not emphasized in their churches thanks to the Seeker Friendly Movement, The Prosperity Doctrine, and Mega Church ideology. Sources: Church History in Plain Language, Bruce Shelley, 4th Ed. and The Jesus Revolution: How God Transformed An Unlikely Generation, Greg Laurie and Ellen Vaughn).
For anyone who likes Gregorian chant - we had a workshop and then Solemn First Vespers on the Eve of the Assumption (Anglo-Catholic church). https://www.youtube.com/watch?v=rC-...vELjMK6Sb0Ky7NbFlbkOoCMt8fGQQziia9jf8wMi4AJn0