Bidagha clasped his strong hands on his breast. His black hair, curling over a high, olive forehead, was held in place by the narrow green band of his calling. Under his little mustache his mouth was firm and serene, and his gray eyes were exalted as he stared at the fading yellow star. "At last!" he said. * * * * * The bluish sun of Zenob had risen by the time Pehn got home. He sat through the family breakfast with his parents and his sister, thankful that his night's absence had apparently not been noticed. Pehn's father, old Premier Karn, represented, the old man liked to think, the ideal of Zenobian maturity. The placidity of his mind was reflected in the soft roundness of his unlined face, and his full lips curved at the corners in perpetual contentment. Like most of his countrymen, he had never felt any conflict between his own impulses and the customs of his society, and never in his life had he needed the ministrations of a Healer. In his usual benevolent mood this morning, Premier Karn entertained his family with his meditations on his favorite theme, the glories of Zenob's history and the perfection of her knowledge. They listened to his remarks in patient silence. As he sipped at his last cup of fragrant _akhlai_, he tried to make a kindly remark to his son. "And what progress is your institute making towards practical atomic power, Pehn? Foundations of this work were laid down more than two hundred years ago, and government would be glad to have demonstration at any time." "We're little uncertain, sir, when that will be. We want to be sure, before our first trial, that we have checked against even vaguest possibility of starting widespread chain reaction." The Premier frowned, set down his cup, and touched his napkin to his lips. "But how could this occur?" "It is not at all likely. But if, for example, as has been suggested, crust of our planet should contain large quantities of some heavy element with properties we don't know about, something related to 235 or 238 for instance, and easily fissionable, our very first trial might prove disastrous." "Nonsense, nonsense!" said the Premier. "Complete chemistry of our planet was worked out and tabulated more than three hundred years ago. There were great chemists in those days, and since then no further research has ever been necessary. There could not possibly be any elements which we don't know about. It is not seemly for you young men to be questioning work of great geniuses of past." Pehn's sister, Soma, had been silent, as befitted a woman. Now she said, "Father, I have been told that long time ago, Sarkar Talat, after life spent in philosophical research, gave Warning to government--"