"Message from outside on my radio pickup," said the Hope.ful's computer.

"Let's hear it," said Fargo.

It came promptly in forceful, clearly enunciated words: "Strangers, you have entered our planetary space without permission. Speak and reveal yourselves and your purpose."

The language was, of course, Jamyn, and Norby translated for Fargo.

"I think it would be more polite to answer from the airlock, in person," said Fargo. "It shouldn't be too risky. The airlock door can be closed quickly if the Mentor makes a sudden move. And since you speak Jamyn, younger brother, you'll have to be the one to take the chance."

"Maybe I should be the one to do it," said Norby, "I speak Jamyn like a native."

"No," said Jeff, who didn't like Norby's reference to being a native. "I think it would confuse the Mentor if you appeared. He's probably never seen a robot like you, and if he can sense that you are part Jamyn, he'll wonder how you came to be on this spaceship. I don't think it's a good idea for them to find out we're from the future. In fact," Jeff frowned and shook his head, "suppose we do or say something that changes the future?"

"Just being here and being seen may have done that, " said Fargo, "but what's the difference? Now that we are here, let's see it through. These robots may look like newer versions of the ones you met in our own time, but they don't give me the impression of being aggressive. They seem reasonable."

"I don't know what you base that on, Fargo," said Jeff, "but if you really think so…Hey, look at that! There's Oola!"

Oola, or a creature exactly like the one who had originally emerged from the hassock, bounded out of the castle and stopped beside the Mentor who had spoken. She wagged her tail.

Jeff said, "She must have realized we're here."

"No," said Norby. "Don't be ridiculous. You two haven't been born yet. She can't possibly…"

"And it might not be our own Oola," said Fargo, sounding a bit depressed at the thought. "There are probably lots of All-purpose Pets on this world, just as there are lots of big robots. Presumably, they've only just begun to unpack the little gardening robots and those police robots you saw running around the castle."

The computer said, "The message from outside has just been repeated a bit more forcibly."

"We'd better get going," said Jeff with a sigh. He opened the airlock and stood just inside the outer door. He smiled in what he hoped would seem like a friendly fashion, then he remembered that on Earth some animals thought baring the teeth was a sign of hostility. He looked serious at once and said, in Jamyn, "I greet you."

"Ah," said the Mentor in a deep voice. "You know our language."

"Yes:' said Jeff. "We are friendly people who are interested in this world which we have come upon in our travels. We hope you will help us by explaining what your world is like, who you are, and what you are doing here." He spoke very slowly, trying not to make any unfortunate mistake in his Jamyn, and trying also not to give away too much about themselves. Behind him, he could hear Norby translating for Fargo.

The Mentor stared at Jeff as though it were uncertain what to say in response to the boy's bold statement. And while the silence held, the All-Purpose Pet suddenly changed her shape.

"What's she doing?" asked Fargo in a whisper from behind him.

Jeff whispered. "I was trying to concentrate on her because looking at the Mentor makes me a little nervous, and it just occurred to me that our Oola had never gotten round to looking like a bear and this one changed immediately."

The Mentor looked down at the All-Purpose Pet who might or might not have been Oola. The little bear was sitting on its haunches and waving its forepaws at Jeff.

"Interesting:' said the Mentor. "According to data left in our main computer by those who made us, there were creatures in the form of this little one, but much larger, on an icy planet they visited. There were also creatures rather like you in appearance whom they took to another planet for a suitable civilizing procedure. Are you those specimens?"

"No," said Jeff. "We travel on our own. Did your makers take a cave bear, too-the creature that, in form, was like the one beside you, now?"

"They did indeed bring specimens of various animals for us. We-I-bioengineered some creatures into this All-Purpose Pet. Some resembled the shape she had when she came out of the castle. The originals had large and undesirable fangs. I constructed something smaller and more affectionate; altogether more suitable as a pet."

"Fargo!" said Jeff, turning back to him. "I think Oola may have been bioengineered from a saber-toothed tiger-a smilodon-but there may have been some cave bear thrown in, along with other Ice Age…"

The Mentor interrupted him. "It is impolite to talk in another language that we do not know," he said in reproving tones.

"I'm sorry," said Jeff, and he tried to explain about Oola, but succeeded only in getting muddled in his attempt to avoid mention of time travel. That proved useless under the penetrating stare of the large robot.

"I think I understand," said the Mentor. "I doubt, though, that these animals you speak of, smilodons and cave bears, are your contemporaries. You do not speak of them as though that were true, and you are sufficiently different in behavior from the specimens taken by our makers to make it reasonable to suppose you are from the future of that planet. If you are, do not tell us anything about the future, because we do not want to know."

"Smart robot," muttered Fargo, when he heard the translation.

"We are in trouble," said Jeff, carefully refraining from comment on what the robot had said about the future. "We need to know who you are and what you are doing on Jamya."

"We Mentors," said the robot, "were activated by the main computer in the castle. It is our task to bioengineer the most promising species on this planet and to train them to become civilized and self-sufficient. You have met the Jamyn?"

"We've seen them. Large animals."

"Too large. And too stupid. We'll change that, though, for they have definite possibilities. For that, we need a simple planet like this with one landmass and one intelligent species. We are here to keep-to keep-a home going."

The big robot looked down at his feet, as if he were emotionally upset. Jeff thought it wasn't any wonder that Norby had emotive circuits.

"A home for the Others?" Jeff said.

The robot's huge head turned up to Jeff. "You know of the Others? I referred to them only as our makers."

"Only that they exist. What are they like? When will they return here?"

"I am disappointed," said the Mentor. "I had hoped you would know. Before they left the castle and its computer on this planet, Jamya, they erased from the computer all knowledge of their appearance and former history. All that is left in the computer is the bare fact that they existed, and were here for a time. After they left, the computer activated us and we began our work, but we wonder about the Others. We would like to know the organic creatures who made us."

"How do you know they were organic? Perhaps they were robots, too."

"There is physical evidence that they were organic. There were the remains of food-preparing machines. There were cremation ashes which we analyzed and which seemed to show residues of proteins and nucleic acids such as those in the living creatures of this planet and, no doubt, in you."

"Could you deduce anything about the appearance of the Others?"

"They could not have looked like you because your bodies have the wrong shape to use their equipment, but that is about all we can say. It is a problem that bothers us considerably."

"Jeff," whispered Fargo with clear worry, "I think we've got to know. Ask him if the Others bioengineered the primitive human beings they found on Ice-Age Earth, and if that's what he meant by saying we were different from the people that were found there."