Apocalypse Revealed #445
445. And the four angels were released. (9:15) This symbolically means that when the external bonds were removed, the interiors of their minds became apparent.
This follows from the explanations above.
Isaiah 8:7-8
7
now therefore, behold, the Lord brings upon them the mighty flood waters of the River: the king of Assyria and all his glory. It will come up over all its channels, and go over all its banks.
8
It will sweep onward into Judah. It will overflow and pass through; it will reach even to the neck; and the stretching out of its wings will fill the breadth of your land, Immanuel.