"That's all you can see it as—an historical document? The significance of the planetary change escapes you?"

"It doesn't escape me," Brucco answered briefly, "but I cannot see that it has any relevancy today. The past is unchangeable and we must fight in the present. That is enough to occupy all our energies."

Jason felt too exhausted to argue the point any more. He ran into the same stone wall with all the Pyrrans. Theirs was a logic of the moment. The past and the future unchangeable, unknowable—and uninteresting. "How is the perimeter battle going?" he asked, wanting to change the subject.

"Finished. Or in the last stages at least," Brucco was almost enthusiastic as he showed Jason some stereos of the attackers. He did not notice Jason's repressed shudder.

"This was one of the most serious breakthroughs in years, but we caught it in time. I hate to think what would have happened if they hadn't been detected for a few weeks more."

"What are those things?" Jason asked. "Giant snakes of some kind?"

"Don't be absurd," Brucco snorted. He tapped the stereo with his thumbnail. "Roots. That's all. Greatly modified, but still roots. They came in under the perimeter barrier, much deeper than anything we've had before. Not a real threat in themselves as they have very little mobility. Die soon after being cut. The danger came from their being used as access tunnels. They're bored through and through with animal runs, and two or three species of beasts live in a sort of symbiosis inside.

"Now we know what they are we can watch for them. The danger was they could have completely undermined the perimeter and come in from all sides at once. Not much we could have done then."

The edge of destruction. Living on the lip of a volcano. The Pyrrans took satisfaction from any day that passed without total annihilation. There seemed no way to change their attitude. Jason let the conversation die there. He picked up the log of the Pollux Victory from Brucco's quarters and carried it back to his room. The wounded Pyrrans there ignored him as he dropped onto the bed and opened the book to the first page.