of value. What a task that must have been!"
Alvin scarcely heard him. He was looking at the curious marker that had first drawn him to this spot-the slim shaft Pinged by a horizontal circle a third of the way down from its up. Alien and unfamiliar though it was, be could respond to the mute message it had carried down the ages. Underneath those stones, if he cared to disturb them, was the answer to one question at least. It could remain unanswered; whatever these creatures might have been, they had earned their right to rest.
Hilvar scarcely heard the words Alvin whispered as walked slowly back to the ship.
"I hope they got home," he said.
"And where now?" asked Hilvar, when they were once more out in space.
Alvin stared thoughtfully at the screen before replying.
"Do you think I should go back?" he said.
"It would be the sensible thing to do. Our luck may ad hold out much longer, and who knows what other surprise these planets may have waiting for us?"
It was the voice of sanity and caution, and Alvin wad now prepared to give it greater heed than he would have done a few days before. But he had come a long way, and waited all his life, for this moment; he would not turn bar while there was still so much to see.
"We'll stay in the ship from now on," he said, "and wn won't touch surface anywhere. That should be safe enough surely."
Hilvar shrugged his shoulders, as if refusing to accept any responsibility for what migt happen next. Now that Alvin was showing a certain amount of caution, he thought it unwise to admit that he was equally anxious to continu! their exploring, though he had long ago abandoned all hopl of meeting intelligent life upon any of these planets.
A double world lay ahead of them, a great planet with 1 smaller satellite beside it. The primary might have been the twin of the second world they had visited; it was clothed it that same blanket of livid green. There would be no point it landing here; this was a story they already knew.
Alvin brought the ship low over the surface of the satellite, he needed no warning from the complex mechanism which protected him to know that there was no atmosphere here. Al shadows had a sharp, clean edge, and there were no gradation between night and day. It was the first world on which he had seen something approaching night, for only one of the more distant suns was above the horizon in the area where they made first contact. The landscape was bathed in a dull rep light, as though it had been dipped in blood.
For many miles they flew above mountains that were sti) as jagged and sharp as in the distant ages of their birth. This was a world that had never known change or decay, hay never been scoured by winds and rains. No eternity circuit were needed here to preserve objects in their pristine fresh ness.
But if there was no air, then there could have been no life -or could there have been?
"Of course," said Hilvar, when Alvin put the question d him, "there's nothing biologically absurd in the idea. Lift can't originate in airless space-but it can evolve forms that will survive in it. It must have happened millions of times, whenever an inhabited planet lost its atmosphere."
"But would you expect intelligent life forms to exist in a vacuum ? Wouldn't they have protected themselves against the loss of their air?"
"Probably, if it occurred after they achieved enough intelligence to stop it happening. But if the atmosphere went while they were still in the primitive state, they would have to adapt or perish. After they had adapted, they might then develop a very high intelligence. In fact, they probably would-the incentive would be so great."
The argument, decided Alvin, was a purely theoretical one, as far as this planet was concerned. Nowhere was there any sign that it had ever borne life, intelligent or otherwise. But in that case, what was the purpose of this world? The entire multiple system of the Seven Suns, he was now certain, was artificial, and this world must be part of its grand design.
It could, conceivably, be intended purely for ornament to provide a moon in the sky of its giant companion. Even in that case, however, it seemed likely that it would be put to some use.
"Look, said Hilvar, pointing to the screen. "Over