There is her heart. I've never seen one beating.I had no idea they moved so much. You put your hand on your heart and you picture something pulsing slightly but basically still, like a hand on a desktop tapping Morse code. This things is going wild in there. It's a mixing-machine part, a stoat squirming in its burrow, an alien life form that's just won a Pontiac on The Price Is Right. If you were looking for the home of the human body's animating spirit, I could imagine believing it to be here, for the simple reason that it is the human body's most animated organ.

- Mary Roach