A man stood there, leaning on a bent staff, smiling gently. He was clad in a loose woolen garment, white as falling snow. His arms and legs were bare and brown. His face, though lined and creased, seemed almost youthful. "I have waited many years," he said softly, "and no one ever came. Now--at last--there is someone who has found the city. Welcome. I bid you welcome to the Tower of the Ancients!" "Stasor!" cried Angus in sudden recognition. "The Stasor you know, yes. One of my race is chosen to spend a hundred years as Guardian of the City, to wait for any who might come to seek its treasures. You are the first who ever found it." Angus said, "A lifetime of loneliness. Are we worth it?" The old man laughed. "We do not die--not as your race knows death. It's one of our attainments. Like the blackness where you first saw me." "The blackness?" Angus turned, stared down at the metal collar encasing the jet black pool. "What is it? It must be all over the planet. No one knows what the pool is." "It is the greatest product of my race. Many eons ago a scientist discovered that an atom may be split to create ravening energy. For years the mightiest scientists of the Elders studied that fact. Eventually they built machines that could house such awful power. Finally, after many centuries, they developed the pools. "The pools are nothing more than that atomic radiation--sheer energy--bottled up in vast chambers lined with _stalabasil_. Ready for use at any time. "In the early days men died from such radioactivity. As time went on and we handled it more and more, our bodies evolved, so that the painful burns that caused death became as mere tinglings along the nerve-ends. Your own race, that evolved on Karr after the Elders went on, is also immune to it." "Reservoirs of energy," murmured Angus, rubbing hand on thigh. "If you could harness that energy and turn it into channels of production...." His blue eyes widened as breath caught in his throat. Stasor smiled, his old head nodding. "That's what we Elders used. We powered our machines with it. We needed no fuel, no refilling of bins or tanks. It was always there, ready to tap." "Does the Book of Nard mention it?" The old man nodded. "All our secrets are contained in the Book of Nard. Do you want to see it?" They went up a flight of spiralling steps and into a room where heavy golden drapes hung bright and splendid. On a wooden rest lay a closed book, its covers solid gold, its parchment leaves tinted a pale rose. "Open it," said the Guardian. Angus bent and lifted the cover. He gazed on the archaic lettering etched into the thick vellum.