“In the so-called Golden Age of American science fiction, when the late John W. Campbell, editor extraordinary, gathered around him in a handful of months the greatest stable of science fiction talent ever seen, he would throw out challenges to his writers, like: "Write me a story about a man who will die in twenty-four hours unless he can answer this question: 'How do you know you’re sane?'"; and this one — surely one of the most provocative of all: "Write me a story about a creature that thinks as well as a man, but not like a man."”