Beautiful and simple melody. Begins with single notes, progresses to some drones, then into a full accompaniment. Rhett is an extremely knowledgeable liturgical musician. His footnotes on this piece follow: One of the five beautiful hymns St. Thomas Aquinas (1225 – 1274) composed at the request of Pope Urban IV (1261 – 1264), to commemorate the establishment of the Feast of Corpus Christi in 1264. The hymn is found in the Roman Missal as a prayer of thanksgiving after Mass. It is also associated with Gregorian Chant. INTERMEDIATE, ALL HARPS.