Apocalypse Explained # 528
528. Verse 13. And I beheld, and I heard one angel flying in the midst of heaven, saying with a great voice, Woe, woe, woe, to them that dwell on the earth, by reason of the other voices of the trumpet of the three angels which are about to sound!- "And I beheld, and I heard one angel flying in the midst of heaven," signifies the Lord enlightening all in the heavens concerning the state of the church at its end; "saying with a great voice," signifies in manifestation; "Woe, woe, woe, to them that dwell on the earth by reason of the other voices of the trumpet of the three angels which are about to sound," signifies grievous lamentation over the changes of the state of the church, on account of the turning away from good and truth, and thence damnation.
Heaven and Hell # 126
126. Light and Warmth in Heaven
People who think solely on the basis of nature cannot grasp the fact that there is light in the heavens; yet in the heavens there is so much light that it is vastly greater than noonday light on earth. I have seen it often, even during our evenings and nights. At first I was amazed when I heard angels saying that our world's light was nothing but shadow in comparison to heaven's light, but now that I have seen it, I myself can bear witness. Its brightness and brilliance are beyond description. What I have seen in heaven I have seen in that light, and therefore more clearly and distinctly than what I have seen in this world.