It's the only thing you really own, unless you believe in God. It's what you can share with someone fully. It's the meeting point, the mediation point, but it's not a point, it's all over. It's the limit of your knowledge and even that is tricky. You sell it every day when you go to work. You trade its location for a salary. It's constantly in motion, constantly changing, and finally it breaks down. Then where are you?