Katha furrowed her thin black brows. "But what _ardth_ ever built such a tower on Lyallar?" she wondered. Tyr pushed open the big wooden door. The round room was walled with dials and panels, cool and dim. It gave off a faint and musky smell. A circular table was covered with vials and belljars and retorts. Shelves lined the walls, and bottles lined the shelves. At the far side of the room, a metal stairway twisted its way to the upper floors. Katha wandered around, delight shining in her eyes. She lifted vials and smelled at chemicals. Laughter gurgled in her throat. "But this is marvelous. It's almost as complete as my own lab. Now who built this place, Tyr? Can you tell me?" He showed her a big book bound in tooled leather. "William Rohrig!" she cried at sight of the golden letters stamped into the cover. "Why--why, he was an _ardth_ genius! We often wondered what became of him! He was to travel to Antares, to study life conditions on one of its outer planets. Commander Mason would be delighted--" She broke off, glancing sideways at Tyr. He said, "If it were not for me, you could go back. You could go anyhow. I--" Her white palm covered his mouth. "Don't say it, Tyr. We'll see this through, you and I." "If there were only some way in which I could convince the _ardth_ that they and the Trylla could live in peace! The Trylla mistrust me and the _ardth_ hate me, for I threaten their power. Katha, Katha! There is no answer." "There is always an answer to a problem. The only trouble is, it takes a long time to see it." While Tyr worked at the table, making tests and experiments under Katha's guidance, to test the powers of his mind, Katha made the tower her own. Sunlight bathed Tyr through an open window. Above him he heard her footsteps going to and fro, heard her lifting things, and the squeals of delight when she unearthed notebooks that had once been Rohrig's. They spent their days in work and laughter. Katha made many tests on him, saying, "You are a biological miracle, darling. I don't know much about miracles, so I have to learn, slowly and gropingly." * * * * * But she never completed her findings. For one day she discovered, tucked into a corner of the big desk on the second floor, a dusty old diary. For three hours she sat entranced with it, never stirring, until Tyr came hunting her, anxious over her silence. He found her with tears in her eyes, her white teeth nibbling at her full lower lip. She looked up at his entrance whispering, "Do you know your name, Tyr? Your full name?" "Tyr. A ring round my neck bore it." "Those were only your initials. Your real name is Theodore Young Rohrig. Your father was William Rohrig. You are _ardth_, Tyr!" He stared at her. She clapped her hands, black eyes glowing.