Yet it never occurred to me in those early days that the biggest job that I would undertake would be writing about O'Hara. Nor to him, I am sure. Adventure--yes, he had expected adventure, but not of the sort to interest anyone except himself and possibly his surviving relatives. The doubtful thrills of supersonic speed, the sensation of flirting with death from atomic poisoning, the constant prospect of plunging through the polar icecap at better than two thousand miles an hour--these, perhaps, O'Hara anticipated as the ultimate possibilities of his career in the Patrol. And then, always, he would be closest to the riddle that since his childhood had absorbed him, flying his charted course along the outer fringes of that dense wall of radiation that enclosed like the half of a glass globe the Western Hemisphere--the Atomic Curtain. Neither of these were careers a native of the Prefecture of Britain would have selected, but the truth is that they were among the best open to us. Our two families had come together to England in that great migration from North America which immediately preceded the establishment of the Atomic Curtain. I remember O'Hara, then not quite eighteen years old, questioning his father one night when I was visiting him, as I often did, for he was my idol in those days, much bigger than I and much bolder. I had never dared to ask these things. "Why did our people leave America?" he asked. "It was their country, wasn't it?" "Yes, their country," his father answered solemnly, for that word--_country_--still had a peculiarly religious sound to it, however outmoded it had now become. "But they--your ancestor and those who agreed with him--believed that what America was going to do was wrong." "Excuse me, sir, I don't see why it was," O'Hara said. "If the Americans--the Yanks"--and how he loved that word--"didn't like the rest of the world, why shouldn't they have cut themselves off from it?" "I'm sorry, Emmett, you're too immature to understand," his father answered. "Isn't that the answer that men give when they themselves do not understand?" O'Hara persisted, and I held my breath. But his father considered that, as he always considered anything O'Hara said--they were people of logic, people of the exploring turn of mind. At last he said, "Yes, that is true. I've never really understood why they did it. When I was your age, I asked my father these same questions. It seemed unfair that we should have given up what I had so often heard was a considerable position in that world--in North America--to come to this crowded hemisphere as emigrants, as a suspected people, second class by birth and law, and solely in obedience to the dictates of an ideal. But your grandfather himself was a little vague upon these points--after all, he did not remember the trip, he had only heard of it, how his people had been forced to give up all possessions, to begin life anew in a country already too poor to support its own citizens."