Albert Barnes Commentary Revelation 8:5

"And the angel taketh the censer; and he filled it with the fire of the altar, and cast it upon the earth: and there followed thunders, and voices, and lightnings, and an earthquake." — Revelation 8:5 (ASV)

And the angel took the censer (Revelation 8:3). This is a new symbol, designed to furnish a new representation of future events. By the former it had been shown that there would be much prayer offered; by this it is designed to show that, notwithstanding the prayer that would be offered, great and fearful calamities would come upon the earth. This is symbolized by casting the censer upon the earth, as if the prayers were not heard any longer, or as if prayer were now in vain.

And filled it with fire of the altar. An image similar to this occurs in Ezekiel 10:2, where the man clothed in linen is commanded to go between the wheels under the cherub, and fill his hands with coals of fire from between the cherubim, and to scatter them over the city as a symbol of its destruction. Here the coals are taken, evidently, from the altar of sacrifice (see Barnes on Isaiah 61:1).

On these coals no incense was placed, but they were thrown at once to the earth. The new emblem, therefore, is the taking of coals, and scattering them abroad as a symbol of the destruction that was about to ensue.

And cast it into the earth. The marginal reading is upon, which undoubtedly expresses the meaning. The symbol, therefore, properly denoted that fearful calamities were about to come upon the earth. Even the prayers of saints did not prevail to turn them away, and now the symbol of the scattered coals indicated that terrible judgments were about to come upon the world.

And there were voices—that is, sounds or noises (see Barnes on Revelation 4:5). The order is not the same here as in that passage, but lightnings, thunderings, and voices are mentioned in both.

And an earthquake (Revelation 6:12). This is a symbol of commotion. It is not necessary to look for a literal fulfillment of it, any more than it is for literal "voices," "lightnings," or "thunderings."