_Medvirk_, Ulv had said. A life form that co-operates and aids other life forms. It may kill in self-defense, but is essentially not a killer or destroyer. Ulv had a lifetime of knowledge about the interdependency of life. He grasped the essence of the idea and ignored all the verbal complications and confusions. He had killed the magter, who were his own people, because they were _umedvirk_--against life. And saved his enemies because they were _medvirk_. With this realization came the painful knowledge that the planet and the people that had produced this understanding were dead. * * * * * In the cavern the magter saw the destruction of their plans, and the cave mouth from which the bullets had come. Silently they rushed to kill their enemy. A concerted wave of emotionless fury. Brion and Ulv fought back. Even the knowledge that he was doomed no matter what happened could not resign Brion to death at the hands of the magter. To Ulv, the decision was much easier. He was simply killing _umedvirk_. A believer in life, he destroyed the anti-life. They retreated into the darkness, still firing. The magter had lights and ion-rifles, and were right behind them. Knowing the caverns better than the men they chased, pursuers circled. Brion saw lights ahead and dragged Ulv to a stop. "They know their way through these caves, and we don't," he said. "If we try to run, they'll just shoot us down. Let's find a spot we can defend and settle into it." "Back here," Ulv gave a tug in the right direction, "there is a cave with only one very narrow entrance." "Let's go!" Running as silently as they could in the darkness, they reached the deadend cavern without being seen. What noise they made was lost in other footsteps that echoed and sounded through the connecting caves. Once inside they found cover behind a ridge and waited. The end was certain. The magter ran swiftly into their cave, flashing his light into all the places of concealment. The beam passed over the two hidden men and at the same instant Brion fired. The shot boomed loudly as the magter fell. Even if his loss was not known, the shot would surely have been heard. Before anyone else came into the cave, Brion ran over and grabbed the still functioning light. Propping it on the rocks so it shone on the entrance, he hurried back to shelter beside Ulv. They waited for the attack. It was not long in coming. Two magter rushed in and died. There were more outside, and Brion wondered how long it would be before they remembered the grenades and rolled one into their shelter. An indistinct murmur sounded outside and some sharp explosions. In their shelter, Brion and Ulv crouched low and wondered why the attack didn't come. Then one of the magter came in and Brion hesitated before shooting. The man had _backed_ in, firing behind him as he came.