“It isn’t good,” he said for them.

“That is correct. The neural folds have closed to form the neural tube, but there is no nerve tissue within it. It therefore seems likely that the baby will be born without a brain.”

Ariel had been prepared to hear those words. She took a deep breath, let it out, and said, “Not this baby, it won’t. Abort it.”

The medical robot whom she had addressed backed up a pace and stammered, “I, I cannot do that.”

“You can and you will. You just told me it won’t have a brain. That means it won’t be human, and it isn’t human now. I want it out of me.”

Slowly the robot said, “I have been programmed to consider anything with the proper genetic code to be human. No matter what deformities it may have, the embryo you carry is human by that definition.”

“Well I’m changing the definition! I tell you it won’t be, and I order you to abort it!”

The robot lost its balance, caught itself, and whispered, “I am sorry. I cannot.” It tried to back away, but lost its balance again and toppled over, dead.

“Frost, I don’t need this,” Ariel muttered. She pointed to another medical robot. “You. Listen to me. I-”

“Wait,” Derec interrupted. “You’ll get the same result with that one. Let me try changing its definition directly.” He turned to the robot. “What is your designation?”

“I am Human Medical 3,” the robot responded. Was that a trace of nervousness Derec heard in its voice? He’d as much as said he was going to reach into its brain and stir. The robot’s Second Law obligation to follow human orders overrode his normal Third Law reluctance to allow it, especially now that Avery had reinforced the Second Law, but that didn’t mean the robot couldn’t still fear for its own existence.

“I won’t harm you,” Derec said for its benefit. Central core. Update programming for Human Medical 3. Definition of human as follows: Any sentient organic being. This is not to include undeveloped beings.

Acknowledged.

“Now, remove the embryo.”

Human Medical 3 obediently reached toward a tray of instruments, but he stopped halfway. “I am experiencing…difficulty,” he said in a halting voice.

“What’s the problem? It’s not human. You know it’s not human. It has no chance of becoming human. Why can’t you do it?”

“I-am programmed to care for human life. All such life. The oath of Hippocrates, which human doctors customarily take before beginning practice, specifically states that they will protect life ‘from the moment of conception., I am not bound by that oath, but it is a definition that I cannot ignore. Nor can I ignore the definition given every robot in the city yesterday by Doctor Avery. Now you add a third definition. It is the most recent one, but it is not the only one. My brain is an analog device, not digital; it is composed of positron pathways, each with a varying potential. Past potentials may weaken, but they never disappear. I cannot forget completely. I now have three conflicting potentials, and a life lies in the balance. Please, do not order me to take it.”

Derec fumed. Ariel had taken the news stoically, but it had to have been a blow for her. This arguing with the medical robots wasn’t helping her a bit.

But it was obvious that ordering the robot to do it would only result in another dead robot, and that wouldn’t help either.

“Cancel,” he growled. Over the comlink, he sent, Get me Avery.

A moment later, he heard Avery’s voice in his head. What is it?

We ’ re in the exam room. Can you come down here?

How important is it? I ’ m in the middle of something here.

It ’ s important.

Avery sighed audibly. All right. Be right there.

›“Avery’s coming,” Derec said to Ariel.

This time she didn’t say anything snide. They both knew that Avery was a better roboticist than Derec; if anybody could convince a robot to abort a malformed embryo, he could.

But it appeared, after they explained the situation to him and he tried reprogramming and re-reprogramming the medical robots, that he couldn’t do the job, either. The robots had had one too many redefinitions already, and they couldn’t handle another. Avery sent the single survivor away in frustration.

Ariel had gotten up from the examination table and was now standing beside Derec, their arms around one another and her head resting against his shoulder. Avery looked up at her from his chair before the computer terminal where he had attempted the reprogramming and said, “I’m sorry, my dear. It looks like you ‘II have to wait until we return to the original Robot City, or to Aurora.”

She nodded. Avery made to get up, but Ariel suddenly asked, “Can’t we make another medical robot, one with a narrow definition of human from the start?”

Avery looked embarrassed. “I would have thought of that eventually.” He turned back to the computer and began entering commands.

I have a question,a voice said in Derec’s head.

Who is this?

Lucius.

Lucius! Where are you?Derec turned his head from side to side, trying to get a fix, but the impression was fuzzy, as if coming from a wide area. Were all three robots transmitting simultaneously, to mask their locations?

Nearby. I have been monitoring your efforts.

You ’ ve been spying on us?

You could call it that, yes. I prefer to think that I am continuing to research the Laws of Humanics. Before you abort the embryo Ariel carries, I need to ask a question that you may not have considered yet.

What question?

If the baby were to grow to term, then be provided with a positronic brain, would it then be human by your definition?

Derec’s answer was instinctive, but no less correct for that. He shook his head violently. No!

“What’s the matter?” Ariel asked.

“Lucius,” Derec whispered. “He’s talking to me.”

“Is he-”

Why not?

“Just a minute.” It wouldn ’ t be human because it wouldn ’ t have a human brain, that ’ s why not! That ’ s the most important part.

You seem quite certain of this.

Of course, I ’ m certain.

I am unconvinced.

This time it was Ariel who flinched, but it wasn’t from anything Lucius said. She pulled away from Derec, shouting, “A rat!”

“Where?” Avery demanded.

She pointed toward the doorway, where a whiskered face was just peeking around the jamb.

“That’s mine!” Avery shouted, jumping up from his chair and lunging for it. The face disappeared with a squeak

“Stop! “ Avery ran out into the corridor, but his footsteps ceased abruptly. Derec and Ariel heard him laugh. He came back into the room holding the rat by the tail. It didn’t hang the way a rat normally did, with its feet spread wide. It looked more like a toy rat molded into a running position.

Avery laid it on its back on the exam table. “Stand up,” he said to it, and it obediently rolled over and stood on its feet.

“Squeak.”

The rat squeaked.

“Lift your right front paw.”

The rat lifted its right front paw.

“I’d say we have our answer,” he said to Derec. “You replace an organic brain cell by cell with a robot brain, and you still wind up with a robot.” To the rat, he said, “Go wait for me in the lab.” He pointed toward the door, and the rat jumped down from the table and scurried away through it.

I am convinced,Lucius sent.

Yousaw that?

I did.

How did you manage that?

If I reveal myself, will you promise that I will not be harmed?

Why should I promise you that?

Because I ask it as a friend. And I offer my help as a friend.