In the mists of history, it is sometimes difficult even to determine the composer of a piece of music, much less any details about its composition or its life in the lives of the people who sang it. In the (rare) case of Hildegard of Bingen, the first issue isn't really present: she seems to have carefully overseen a compilation of a great deal of her liturgical chants into manuscript form sometime during her lifetime. The second is also less problematic in her case, as her very compilation specifies the saint or divine being to whom each piece is dedicated, and her generic musical forms are clear. In the case of one of her pieces -- amazingly -- we even have a contemporary narrative of the third question: its performance life! A brief passage in her spiritual biography speaks of the revered Abbess walking through the monastic cloister singing the piece whose incipit is O virga ac diadema, a sequence to the Virgin Mary, which is preserved among her other chants. Scholars think it must have been one of her favorite pieces of music to so occupy a moment in this biographical document.
Hildegard's own Latin poem for O virga ac diadema gushes with her characteristically rich allusiveness. The poetess opens with a particularly regal set of images, Mary as "scepter" and "breastplate"; she quickly moves, on the other hand, to a different translation of virga, and expounds upon Mary's role as a blessed "branch" within humankind. Mary, Hildegard tells in the fullness of her advanced understanding of natural biology, blossomed not from dew or rain but from the Holy Spirit. The remainder of her text alludes to the Creation in the Garden of Eden, to the first sin of Eve and Adam, and to the parallel obedience of Mary and her Christ Child, which "cleaned away [our] sin." Hildegard's music for this poem is simultaneously restrained and expansive. She follows the musical form of the sequence rather faithfully, dividing the text into pairs of verses, each of which follows much the same melody; her chant is also somewhat more syllabic than her usual. At the same time, she varies the musical motives that mark the verse pairs with some wit, and evolves a powerful melodic sense of what would later be thought of as modal mixture: some verses dip into the plagal depths of the mode, some reach the authentic heights, some mix in alternate Phrygian colorings. ~ Timothy Dickey, Rovi