"I'm lucky," said Quest soberly. "I would have murdered him."

"But why, Quest? I knew he was afraid of you, but he didn't tell me why."

"It was conditioned into me," answered Quest "I didn't know it until just now, when it ended, but my father conditioned me psychologically from my birth to the task of hunting down Dom Blessing and killing him. It was an unconscious drive in me that wouldn't release me until the task was finished.

"You see, Blessing was my father's assistant on Ganymede. Right after my father completed development of the surgiscope, he and my mother blasted off for Io. Blessing wanted the valuable rights to the surgiscope, and he sabotaged the ship's drive so it would fall into Jupiter.

"But my father was able to control it in the heavy atmosphere of Jupiter, and landed it successfully. I was born there, and he conditioned me to come to Earth and track down Blessing. I know now that it was part of the conditioning that I was unable to fight any other man until my task was finished: it might have gotten me in trouble and diverted me from that purpose."

More gently than Trella would have believed possible for his Jupiter-strong muscles, Quest took her in his arms.

"Now I can say I love you," he said. "That was part of the conditioning too: I couldn't love any woman until my job was done."

Trella disengaged herself.

"I'm sorry," she said. "Don't you know this, too, now: that you're not a man, but an android?"

He looked at her in astonishment, stunned by her words.

"What in space makes you think that?" he demanded.

"Why, Quest, it's obvious," she cried, tears in her eyes. "Everything about you … your build, suited for Jupiter's gravity … your strength … the fact that you were able to live in Jupiter's atmosphere after the oxygen equipment failed. I know you think Dr. Mansard was your father, but androids often believe that."

He grinned at her.

"I'm no android," he said confidently. "Do you forget my father was inventor of the surgiscope? He knew I'd have to grow up on Jupiter, and he operated on the genes before I was born. He altered my inherited characteristics to adapt me to the climate of Jupiter … even to being able to breathe a chlorine atmosphere as well as an oxygen atmosphere."