The Pulpit Commentary - Revelation 8:1
And when. καὶ ὅταν , instead of καὶ ὅτε (as in the other seals), is read in A, C, and gives a certain indefiniteness which does not belong to any of the rest (Alford). ὅτε is, however, found in א , B, P, Andreas. He had opened the seventh seal; he opened. As in the case of the other seals, the silence accompanies the opening (see on Revelation 6:1 , Revelation 6:3 , Revelation 6:5 , etc.). This completes the number, and sets the roll free ( Revelation 5:1 ).... read more
Adam Clarke's Commentary on the Bible - Revelation 8:8
A great mountain burning with fire - Supposed to signify the powerful nations which invaded the Roman empire. Mountain, in prophetic language, signifies a kingdom; Jeremiah 51:25 , Jeremiah 51:27 , Jeremiah 51:30 , Jeremiah 51:58 . Great disorders, especially when kingdoms are moved by hostile invasions, are represented by mountains being cast into the midst of the sea, Psalm 46:2 . Seas and collections of waters mean peoples, as is shown in this book, Revelation 17:15 .... read more