"life is like facing the wrong way on the train. because, you see, the present, the bit of countryside that's exactly equal to where you are, is over before you know it's there, and then all you have is the dwindling afterward of it. and though you can guess what sorts of things are going to come rushing over your shoulder, because you can see roughly what sort of terrain you're in, there's always the chance of something really unexpected or scary, like a tunnel, or a field with horses."