"They traveled for days and days. Some were overcome by hunger and fell by the wayside. The most hardy survived to reach Theros, a series of enormous caverns that extends for hundreds of miles under the surface of your country. Here they found subterranean lakes of pure water; forests, game. They had a few tools and weapons and they established themselves in this underground world. From that small beginning came this!" Phaestra's slim fingers worked rapidly at the controls. The scenes shifted in quick succession. They were once more in the present, and seemed to be traveling speedily through the underground reaches of Theros. Now they were racing through a long lighted passage; now over a great city similar to the one in which they had arrived. Here they visited a huge workshop or laboratory; there a mine where radium or cobalt or platinum was being wrested from the vitals of the unwilling earth. Then they visited a typical Theronian household, saw the perfect peace and happiness in which the family lived. Again they were in a large power plant where direct application of the internal heat of the earth as obtained through deep shafts bored into the interior was utilized in generating electricity. They saw vast quantities of supplies, fifty-ton masses of machinery, moved from place to place as lightly as feathers by use of the gravity discs, those heavily charged plates whose emanations counteracted the earth's attraction. In one busy laboratory they saw an immense television apparatus and heard scientists discussing moot questions with inhabitants of Venus, whose images were depicted on the screen. They witnessed a severe electrical storm in the huge cavern arch over one of the cities, a storm that condensed moisture from the artificially oxygenated and humidified atmosphere in such blinding sheets as to easily explain the necessity for well-roofed buildings in the underground realm. And, in all the speech and activities of the Theronians, there was evident that all-pervading feeling of absolute contentment and freedom from care. "What I can not understand," said Frank, during a quiet interval, "is why the Theronians have never migrated to the surface. Surely, with all your command of science and mechanics, that would be easy." "Why? Why?" Phaestra's voice spoke volumes. "Here--I'll show you the reason." * * * * * And again the scene in the sphere changed. They were on the surface and a few years in the past--at Chateau Thierry. They saw their fellow men mangled and broken; saw human beings shot down by hundreds in withering bursts of machine-gun fire; saw them in hand-to-hand bayonet fights; gassed and in delirium from the horror of it all. They traveled over the ocean; saw a big passenger liner the victim of torpedo fire; saw babies tossed into the water by distracted mothers who jumped in after them to join them in death.