If your mind is at work, we're in danger of reproducing another cliche. If we can keep our minds out of it and our thoughts out of it, maybe we'll come up with something original.
The pain comes from knowing that we have never been safe, and therefore will never be safe again. It comes from knowing we can never be so ignorant again. It comes from knowing we can never be children again. Losing innocence. Remembering heaven. That was the essence of hell.