This Sunday’s Offertory chant is one of the true marvels of the Graduale.
And here are Jeffrey Tucker’s wonderfully curated polyphonic treatments, from the Chant Cafe archives.
And here as an update is Philippe de Monte’s version as recorded by The Sixteen.
This Gregorian Offertory has some interesting musical allegories. For instance it begins with the melody from the Requiem Kyrie which alludes to hope after a great loss, and has a comforting message near the end of the respond, a musical motive taken from the beginning of the Offertory for the Feast of the Annunciation which has the angel Gabriel announcing Chairete, "Rejoice" to Mary. To this "Rejoice" is added a motive from the Alleluia of Pascha morning that puts this entire psalmic text in the context of Christ and His Church, from the Babylonian captivity of the Israelites to the context of our captivity to sin, and of course to God's great mercy in giving His Son Jesus for our redemption. While the bread and wine are being prepared on the altar for sacrifice, we are reminded of His Sacrifice on the Cross, and that through His Resurrection we are offered to share in eternal life, made manifest in the Eucharist.
If one is to argue for tone painting in chant this seems to be an example. The melody slowly moves its way up and down its ambitus, like the slow winding of the rivers of Babylon. You can visually see this movement in the staff notation.