Thunderstorm

Recently I dreamt about a thunderstorm. In my dream I was in a strange house at night. I could hear the thunder and see flashes of lightning through the windows. Then I woke up, and there was a thunderstorm outside!

Now, there's nothing extraordinary about that kind of dream. When we're asleep we sometimes hear things which our imagination turns into a dream. 

It is, though, an illustration of how apocalyptic prophecies might depict the real world. In an altered state of consciousness, a seer perceives things in his revelatory dream or vision. And that may correspond to what will happen outside his dream or vision in a fairly straightforward sense. Rather like how I dreamt about a thunderstorm at night while there was, in fact, a thunderstorm at night, outside the my dream. A direct parallel between the real world and the dreamscape.