For something to be cast down or cast out generally refers to a rather dramatic move from a higher spiritual state to a lower one. In most cases it's used in reference to evil desires or false thinking – or people spreading desires and false thinking – being removed and banished, even condemned to hell. Some uses are more moderate, though, and sometimes – when Moses casts down his rod in performing a miracle, for example – it signifies the sudden inflowing of the divine into the natural world.

(Referenser: Apocalypse Explained 497, 1175; Apocalypse Revealed 252, 552, 835, 872; Arcana Coelestia 2657, 6693, 6948; The Apocalypse Explained 1181)

1181. Verse 21. And one strong angel took up a stone like a great millstone and cast into the sea, saying, Thus with violence shall Babylon, that great city, be cast down, and shall be found no more.

21. "And one strong angel took up a stone like a great millstone and cast into the sea," signifies all confirmations of their doctrine from the Word cast with them into hell (n. 1182); "saying, Thus with violence shall Babylon, that great city, be cast down, and shall be found no more," signifies the total destruction of that doctrine and religious persuasion, and that they shall not rise again (n. 1183).