Okay, here's something to do. Prove to me, right now, that you are not dreaming. How can you prove to me, with definite evidence, that you are not dreaming? Saying "I can't fly" wouldn't be good enough- perhaps you're just having a time of not being able to fly? And sometimes you just can't fly anyway! Or "I can't put my hand through my monitor" isn't good enough, because sometimes you can't anyway. Pinch yourself. It hurt? How are you sure you brain didn't just imagine the hurt?