From Robert Silverberg’s “Earthmen and Strangers” anthology, 1966: Randall Garrett’s story examined, from the viewpoint of the Earthmen, a possible encounter between our species and hostile aliens. In the story that follows, Isaac Asimov handles the same theme from the viewpoint of the aliens themselves. Suppose, he says, strangers from afar have been watching us for years. Suppose, too, that t...