Already with Hildegard of Bingen's Scivias, the "Sybil of the Rhine" had declared her interest in various heavenly creatures. She acknowledged in her visionary Christianity the existence of a great heavenly hierarchy; this book concludes with her vision of legions of different creatures praising the name of God before His throne in a grand symphony of praise: the Blessed Virgin Mary and Jesus Christ, the company of divine angels and archangels, the saints who have been martyred for the faith, and virgins who have died rather than sully their vows with carnal exploits. These poems that she had earlier dedicated to the praise of the almighty also appear later in her works with music she composed for their singing in liturgical worship. Angels may have been revered early within the traditions of the medieval Catholic church, but the liturgy for celebrating their place in the heavenly hierarchy remained for a long time subject to local traditions. It is unclear when in her monasteries of Rupertsberg and Disibodenberg Hildegard's nuns may have sung their hymns directly in honor of the angels. That she wrote music for them—two pieces, the antiphon O gloriosissimi lux viviens and this responsory—attest to their importance in her own mind and in their devotion.

Her text for this piece presents a Latin poem, in responsory form and thus appropriate for the celebration of Mass during the feast day for an angelic patron. In it, she (and her nuns) pray to each category of the heavenly host: the angels "who care for the people on whom your form shines"; the archangels who " sustain the souls of the righteous"; the powers, principalities, lords, and thrones who "live in the mysterious fivefold secrets"; and the cherubim and seraphim, who are "secrets of God." Her music carefully follows and reflects this elaborate, mystical, and hierarchical enumeration of the spirits. She begins with a very low and modally uncertain opening, but for the archangels quickly opens the melodic range. At the end of the chant, she gives a wonder of medieval music, and perhaps the most elaborate melisma in all of Gregorian chant: she composes fully 81 notes on one syllable, and follows a melodic arc of more than two octaves across its span! Not only does the melody range over extraordinarily wide ranges, Hildegard shifts quite often between modes, embracing the Phrygian, hints of Aeoloian, and confounding both with sudden and explicit B flat pitches.

© Timothy Dickey, All Music Guide