Why do mirrors reverse left and right, but not top and bottom?

Position yourself in front of a mirror and you'll notice it immediately. The text on your sweatshirt is reversed. The part in your hair has switched to the other side of your reflection's head. The mole on your left ear stares back at you from your mirror image's right earlobe. Before you stands a bauplan reversed;… » 12/26/12 11:09am 12/26/12 11:09am