What kind of world do you live in? A world of solid ground with people and trees, oceans with clouds above it and, higher still, the enormous emptiness of space? Are you one of the billions of people in that world? If you answer "yes" to those questions, then you are mistaken! If you were able to answer "yes" to them, then that means that throughout the course of your life you have probably ignored a most important truth. Your brain is a locked room which you can never step out of, because everything you imagine to be the "outside world" in reality consists of perceptions you experience in the visual or hearing centers of your brain. The "tower" we are speaking of is your body, and the little room atop it (in other words, your world) is your brain.