She was quite the loveliest creature he had ever seen. She was stark naked, and showed no fear when she saw him. She showed, instead, a lively curiosity. She jabbered and smiled at him and came to him, open-handed, interested, friendly. I'll kill her, he told himself, when the pain is too bad, when I can't stand it any longer. She can't get away. She expects nothing, nothing. Meanwhile, he decided to spend the last months of his life with this woman.... * * * * * There was no reason to expect that she had been monogamous. One man or another would be all the same to her, if they could leave this area. If she wouldn't find the corpse of her mate. Jason took her hand, and they walked. They walked for a long time. Then they slept, then ate, then walked again. The woman jabbered. Jason Wall talked. He was enjoying himself immensely. There was no hurry. This was a new kind of life, a new kind of experience. He loved every moment of it. They found another cave, three day's journey from the first. They lived there for some weeks. The pain came more frequently, but Jason Wall withstood it. * * * * * The weeks became months. His days were numbered now, he knew that. It seemed just, somehow. After taking all that the first woman had to offer, he would kill her--and destroy all humankind. She never had understood his affliction, his great pain. Pain from a wound she could understand. Once he had scraped his knee on a rock, and she had been extremely sympathetic. But pain from disease seemed unknown to her. Of course, Jason Wall knew, any disease was compounded of two things: a disease agent, bacteria or virus, and a susceptibility. Apparently First Man and First Woman had utterly no susceptibility. They were disease-free. Some time later in the course of human development--how much later he did not yet know--susceptibility to disease had evolved. The woman's belly grew round and Jason Wall knew she was going to have a baby. His baby. He sighed. His time was short. The baby would never be born, because he would kill its mother first. Then it struck him like a blow. A baby. His baby. And First Man and First Woman--free of disease. He had introduced disease into the human makeup, by planting his seed in this woman! _Including his own...._ He could break the pattern by killing her. Then, as he had planned originally, there would be no childbirth, and no mankind. He lifted the pistol. The look on his face must have given him away. Probably, she thought it was a club. He was pain-wracked and very much weakened by his disease now. She took the pistol away from him easily, and shrugged, and cried a little, and went away. He ran after her. "Wait!" he screamed. "Wait, you don't understand! You've got to die. You've got to--" He fell. His legs drummed feebly. She was gone. The pistol was gone. Humanity would live--the life of torment and pain and disease that it had always known.