They finished the tour at her cabin. From the time that the trip started, and until the last few nights, Fred had insisted on "walking the girl home." And each time, before he left her, he'd quasi-seriously propositioned her with a request that the door be left open. It was always shut, very firmly. Tonight, Fred was grave. Almost curt, he said, "Goodnight. See you in the morning." "Wait." She smiled. "If you could learn to be as happy as we on this planet, you might find the door open." He smiled in return. "I'll think about it. Night." Fred strode away, thinking: Jo, you'd make a lousy Mata Hari. But thanks for convincing me I'm sane! Relief brought emotional reaction; he wanted to laugh, but it was aggressive, humorless laughter, and he couldn't afford it. Instead, he permitted himself the luxury of silent anger. Complete. Total. * * * * * When the curtain of fury dissolved, Fred found himself in the recreation area. Unknowingly, he'd wandered there. Unknowingly, he'd arrived at a course of action-- _You won't have a chance to carry it out._ That voice again! It was inside his head. This time, however, Fred straightened, unconsciously, said, "So I was wrong, and we did find intelligent life." _But not the sort you expected._ "Admitted. It's difficult to believe that a planet is alive." _Why so? Logically, you animals are the difficult beliefs. Nearly all else in the universe is direct--energy conversion, formation of elements, and the like. You animals require many things to get started: a planet; a fluid medium such as water; and the delicate balance of conditions for food input and waste removal. In a sense, you're parasites._ "Certainly. But why are you trying so hard to convince my friends to be parasites?" Fred stopped for a second, struck by a thought. "Come to think of it, why am I immune?" _There is always a certain small percentage who have crossed mental patterns, whom we can communicate with. What the others see as desirable, you dislike. If you'll think a moment, you'll realize you've always been that way._ Fred nodded. He was the eternal pessimist surrounded by optimists. _My desire is simple. I want a population._ "Why?" _We use animal intelligence. When you die, we absorb the life force directly. It sustains our own._ "In a sense," Fred felt he'd scored, "you also are a parasite. You talk as though there are other sentient planets in the universe." _There are, though not in great numbers. Our life cycle is similar to yours. We are born in cosmic space of elemental material; we attract animal populations that have evolved on the dead planets, and thereby gain the energy needed to live--just as you live from the lower animals. We even grow old and die after two or three billion years. But I'm young, and this is the first time I've been in this portion of the galaxy--I need a population._