Imagine: You're at the circus, sitting under that great red-and-white striped tent, watching all the glitz and spectacle. Kernels of popcorn fall from your mouth because you're so mesmerized by the sparkling parade of elephants in the center ring. Then with a grand flourish, the ringmaster bellows into his great yellow bullhorn and the spotlight slides up and up to illuminate the band of acrobats waving from a tiny platform. A thin metal wire stretches before them, and one of the acrobats steps upon it, far above the ground. You lean forward in your seat, captivated. With barely a wobble, she successfully crosses to the other side with a small bow; at the second platform, she's handed a long pole to balance in addition on her walk back. And then her fellow acrobats pile china plates on the ends of her pole, and her arms begin to shake from the weight as she carefully turns to cross again. As the trick becomes more precarious, your popcorn bag is forgotten, scattered...