"They are here, my companions?" asked Orth stupidly. "You mean Horn and Neilson? Did you say that to me?" "He speaks only in thoughts," said Ayna. "When our people reach the age of two hundred they submit to this operation. With their lungs gone there is, of course, no vocal speech. But we live on for centuries untroubled by bodily breakdowns." Ivath motioned with his feeble old arms. "Come," he flashed at them, "we will join them." * * * * * As they sat in a small spacer cruising within the vast hollow of Ivath's world-sized stage, Ayna explained more of the mysteries of this future world. How the planets had been cut up into smaller spheres and moved into the dwindling radiations of Sol. How their fleets of space ships crossed the void to trade and mine the precious elements they required, and of the other galactic cultures they met. "It is sad," said the girl at last, "that you can never return to the past. It is there that our science has utterly failed. Travel in time is but a one-way voyage." "You mean, Ayna," Orth said slowly, "we can't carry back the knowledge of an atomic shield that will arrest the spread of sterility--that mankind must abandon his use of atomic power?" "You cannot go back," smiled Ayna, putting her hand on his shoulder as she spoke. "But there is no need. In 1980--if our records are not too wrong--Eric Ensamoff discovered such a shield." "Great!" cried Orth. "I won't mind being stranded here. There's Ivath to set right on his ancient history. There's your perfected civilization to study." He swallowed his tongue momentarily and recovered it. "And then there's you, Ayna," he blurted. "You're...." The girl slid her fingers across a toggle-switch in the wall. "No use letting all the worlds hear us," she said softly, "much less see us. You see, I was sent to interview you and get your reactions. All the world was watching while you explored." Orth took the girl and pulled her closer. He studied her face. She smiled. "Sure it's turned off?" he demanded. She nodded. "Fine ... no, they don't need to see _this_ reaction...."