Most of us are attracted to the idea that the human race is not alone. Encountering other beings, we believe, will be romantic, exciting, thought-provoking, intriguing. And possibly dangerous. After all, one of our time-honored notions since H.G. Wells is that we may well be perceived by Others as little more than snacks, or subjects for religious conversion, or creatures of such insignificance as to be simply swept aside. No matter, we think cheerfully. We will take the risk.