From the early Church Fathers to now.
“And a mighty angel took up a stone, as it were a great millstone, and cast it into the sea, saying: With such violence as this shall Babylon, that great city, be thrown down, and shall be found no more at all.”
“Babylon is likened to a great millstone which is thrown down, for the revolving of times, as though it were a millstone, grinds down those who love the world, and it sends them in circles. Of these the Scriptures say, "The wicked walk in a circle."”
“Just as a millstone sinks with force into the sea, so also the destruction of this Babylon will be sudden, so that afterward no trace of her will be found. The absence of harpers, minstrels and the rest is an indication of this.”
“And a mighty angel took up a stone like a great millstone and threw it into the sea, saying: With this violence shall Babylon be thrown down. Or (as another edition says): Thus with violence shall that great city Babylon be cast down. The city of the world, due to the weight of sins and error, is compared to an unstable millstone. For the wicked walk in a circle. It is rightly absorbed by the waves of vengeance because it oppressed the citizens of Jerusalem with the waves of infidelity, while they, sitting by the rivers of Babylon, wept for the absence of heavenly Zion. For the Lord said that the authors of scandal should be punished with such a penalty. And indeed the Church is compared to a stone, but stable and firm, which scorns the assaults of storms. The millstone can also be understood as the crushing of punishments. For blessed Ignatius is said to have said when about to suffer: "I am the grain of God, ground by the teeth of beasts, that I may become pure bread."”
The in-app commentary runs from the Fathers to the early-modern record, then stops — that's where the public-domain sources end, not where the reading does. For the modern reading, follow the sources directly.