I think it has to do with that you can only see what you have already in dreams because you can interpret it by association, Jokey. A person in your dream may not be an exact replica of someone you have seen, but your mind can project general concepts so that you can understand. Plus, if you've only seen something for a second, your mind can hold the image even if you're unaware. i.e. You mind doesn't just make stuff up, it has templates. It knows what it is doing because of experience and only a small amount of guess work. :o