Jimmy was out of his spacesuit now and washed up. You always had to wash up after coming in from outside. Even Robutt had to be sprayed, but he loved it. He stood there on all fours, his little foot-long body quivering and glowing just a tiny bit, and his small head, with no mouth, with two large glassed-in eyes, and with a bump where the brain was. He squeaked until Mr. Anderson said, "Quiet, Robutt."
Mr. Anderson was smiling. "We have something for you, Jimmy. It's at the rocket station now, but we'll have it tomorrow after all the tests are over. I thought I'd tell you now."
"From Earth, Dad?" "A dog from Earth, son. A real dog. A Scotch terrier puppy. The first dog on the Moon. You won't need Robutt any more. We can't keep them both, you know, and some other boy or girl will have Robutt." He seemed to be waiting for Jimmy to say something, then he said, "You know what a dog is, Jimmy. It's the real thing. Robutt's only a mechanical imitation, a robot-mutt. That's how he got his name."
Jimmy frowned. "Robutt isn't an imitation, Dad. He's my dog." "Not a real one, Jimmy. Robutt's just steel and wiring and a simple positronic brain. It's not alive."
"He does everything I want him to do, Dad. He understands me. Sure, he's alive."
"No, son. Robutt is just a machine. It's just programmed to act the way it does. A dog is alive. You won't want Robutt after you have the dog."
"The dog will need a spacesuit, won't he?" "Yes, of course. But it will be worth the money and he'll get used to it. And he won't need one in the City. You'll see the difference once he gets here."
Jimmy looked at Robutt, who was squeaking again, a very low, slow squeak, that seemed frightened. Jimmy held out his arms and Robutt was in them in one bound. Jimmy said, "What will the difference be between Robutt and the dog?"
"It's hard to explain," said Mr. Anderson, "but it will be easy to see. The dog will really love you. Robutt is just adjusted to act as though it loves you."
"But, Dad, we don't know what's inside the dog, or what his feelings are. Maybe it's just acting, too."
Mr. Anderson frowned. "Jimmy, you'll know the difference when you experience the love of a living thing."