But now they had twenty billion years to live ere these planets, too, would be dark, cold and sunless. And then they could easily move to some other distant system. But why wait till the Sun grew cold? They were already making investigations. Out across space there still glowed countless millions of unexplored stars! Now there would be no population limit to their peoples; there would be expansion, and since each man lived from two to three thousand years, the expansion could be rapid. Four of the planets were naturally habitable, but five there were which should be so in the future. There was one yet a glowing planet, still hot from its formation. Two were so far from the major sun that they were cold to absolute zero, save when they were in conjunction with the minor sun. These the engineers and astro-physicists had investigated. They would be drawn nearer the sun when the population warranted, and one more that turned on its axis but once a year could easily be started rotating. Air and water it lacked, but that would be easy to supply. And a last planet was so close to the mighty blazing Betelguese that it was kept dull red by the titanic furnace so near it, a scant thirty million miles away. That would be drawn to a more comfortable distance. There was indeed room for much expansion in this system. But still there was the urge of exploration, of adventure. There might be other battles to fight, other worlds to conquer! Already mighty exploration ships were being prepared to dispatch to half a dozen systems. Perhaps they would bring commerce; perhaps it would be wider domain. But it was that same lure of adventure that had driven the first caveman from his rocky cliff to explore the wilder lands. It was the love of adventure, another name for ambition. It would take more than ten thousand thousand thousand years to kill that! THE END