Returning to the music of Hildegard of Bingen, the 12th-century German abbess and mystic, Anonymous 4 explores the theme of the Pentecostal power of the "Fiery Spirit". Hildegard's intensely emotional chants and visions (including the monumental hymn O ignee spiritus and some of her finest antiphons) are presented here framed by hymns and sequences that she and her convent sisters would have heard and sung every day.