Sorry to be belatedly posting--I've been away too long and am catching up. Like some others, I read this story in a "Best of..." collection. By the end, I was having trouble breathing. (I didn't experience that with this audio version, but I remembered very well what was coming.) Reading the responses, I'm surprised that no one brought up claustrophobia. For me, the story was about that trapped and smothered feeling, and really nailed it. I can handle dark, enclosed spaces (a couple years back, I went on one of those caving trips where you don a hard hat with a miner's light and crawl or wriggle through some unbelievably tight spots), but the fear of being blind and buried alive is about as primordial as it gets, I would have thought. Maybe related (in our discussion of the afterlife): God has misplaced these souls. As if they were stuck in a closed drawer by accident, or fell behind one of Heaven's filing cabinets, not to be discovered for a thousand years. That takes claustrophobia to the level of cosmic horror. I think this story will be a classic because it achieves both of those sensations at once.
The discussion of the last line was interesting. I guess when I read the story, I was so choked up / breathless that I received the whimsical line as a gift from the author--"OK, you can snap out of it now!"