What does Isaiah 6:4 mean?
The scene Isaiah describes in these verses is filled with dread and awe. The Lord has caused Isaiah to see Him in the temple, seated on a throne, surrounded by multiple angelic, serpent-like, six-winged seraphim. They stand or fly around the room calling out to each other worshipping about the God's holiness and glory (Isaiah 6:1–3). The following verse shows Isaiah is shaken to his core at this scene (Isaiah 6:5).He now adds that the foundations are shaking from the voices of the seraphim. On top of that, the house is full of smoke. This could be due to smoke of burning incense used in worship or perhaps the "cloud of glory" that sometimes comes when God is near (Exodus 16:10; Isaiah 4:5). In other words, the room is loud, the floor is shaking, the aroma may be intense. And what Isaiah is glimpsing through the thick smoke seems impossible. He knows, though, that it is all terribly real, and that he, as a sinful man, does not belong in such a place (Isaiah 6:5).