"That is not so," said R. Daneel, quietly.

"Yes? We'll let the Doctor decide. Dr. Gerrigel?"

"Mr. Baley?" The roboticist, whose glance had been alternating wildly between the plain-clothes man and the robot as they spoke, let it come to rest upon the human being.

"I've asked you here for an authoritative analysis of this robot. I can arrange to have you use the laboratories of the City Bureau of Standards. If you need any piece of equipment they don't have, I'll get it for you. What I want is a quick and definite answer and hang the expense and trouble."

Baley rose. His words had emerged calmly enough, but he felt a rising hysteria behind them. At the moment, he felt that if he could only seize Dr. Gerrigel by the throat and choke the necessary statements out of him, he would forgo all science.

He said, "Well, Dr. Gerrigel?"

Dr. Gerrigel tittered nervously and said, "My dear Mr. Baley, I won't need a laboratory."

"Why not?" asked Baley apprehensively. He stood there, muscles tense, feeling himself twitch.

"It's not difficult to test the First Law. I've never had to, you understand, but it's simple enough."

Baley pulled air in through his mouth and let it out slowly. He said, "Would you explain what you mean? Are you saying that you can test him here?"

"Yes, of course. Look, Mr. Baley, I'll give you an analogy. If I were a Doctor of Medicine and had to test a patient's blood sugar, I'd need a chemical laboratory. If I needed to measure his basal metabolic rate, or test his cortical function, or check his genes to pinpoint a congenital malfunction, I'd need elaborate equipment. On the other hand, I could check whether he were blind by merely passing my hand before his eyes and I could test whether he were dead by merely feeling for his pulse.

"What I'm getting at is that the more important and fundamental the property being tested, the simpler the needed equipment. It's the same in a robot. The First Law is fundamental. It affects everything. If it were absent, the robot could not react properly in two dozen obvious ways."

As he spoke, he took out a flat, black object which expanded into a small book-viewer. He inserted a well-worn spool into the receptacle. He then took out a stop watch and a series of white, plastic slivers that fitted together to form something that looked like a slide rule with three independent movable scales. The notations upon it struck no chord of familiarity to Baley.

Dr. Gerrigel tapped his book-viewer and smiled a little, as though the prospect of a bit of field work cheered him.

He said, "It's my Handbook of Robotics. I never go anywhere without it. It's part of my clothes." He giggled self-consciously.

He put the eyepiece of the viewer to his eyes and his finger dealt delicately with the controls. The viewer whirred and stopped, whirred and stopped.

"Built-in index," the roboticist said, proudly, his voice a little muffled because of the way in which the viewer covered his mouth. "I constructed it myself. It saves a great deal of time. But then, that's not the point now, is it? Let's see. Umm, won't you move your chair near me, Daneel."

R. Daneel did so. During the roboticist's preparations, he had watched closely and unemotionally.

Baley shifted his blaster.

What followed confused and disappointed him. Dr. Gerrigel proceeded to ask questions and perform actions that seemed without meaning, punctuated by references to his triple slide rule and occasionally to the viewer.

At one time, he asked, "If I have two cousins, five years apart in age, and the younger is a girl, what sex is the older?"

Daneel answered (inevitably, Baley thought), "It is impossible to say on the information given."

To which Dr. Gerrigel's only response, aside from a glance at his stop watch, was to extend his right hand as far as he could sideways and to say, "Would you touch the tip of my middle finger with the tip of the third finger of your left hand?"

Daneel did that promptly and easily.

In fifteen minutes, not more, Dr. Gerrigel was finished. He used his slide rule for a last silent calculation, then disassembled it with a series of snaps. He put away his stop watch, withdrew the Handbook from the viewer, and collapsed the latter.

"Is that all?" said Baley, frowning.

"That's all."

"But it's ridiculous. You've asked nothing that pertains to the First Law."

"Oh, my dear Mr. Baley, when a doctor hits your knee with a little rubber mallet and it jerks, don't you accept the fact that it gives information concerning the presence or absence of some degenerative nerve disease? When he looks closely at your eyes and considers the reaction of your iris to light, are you surprised that he can tell you something concerning your possible addiction to the use of certain alkaloids?"

Baley said, "Well, then? What's your decision?"

"Daneel is fully equipped with the First Law!" The roboticist jerked his head in a sharp affirmative.

"You can't be right," said Baley huskily.

Baley would not have thought that Dr. Gerrigel could stiffen into a rigidity that was greater than his usual position. He did so, however, visibly. The man's eyes grew narrow and hard.

"Are you teaching me my job?"

"I don't mean you're incompetent," said Baley. He put out a large, pleading hand. "But couldn't you be mistaken? You've said yourself nobody knows anything about the theory of non-Asenion robots. A blind man could read by using Braille or a sound-scriber. Suppose you didn't know that Braille or sound-scribing existed. Couldn't you, in all honesty, say that a man had eyes because he knew the contents of a certain book-film, and be mistaken?"

"Yes," the roboticist grew genial again, "I see your point. But still a blind man could not read by use of his eyes and it is that which I was testing, if I may continue the analogy. Take my word for it, regardless of what a non-Asenion robot could or could not do, it is certain that R. Daneel is equipped with First Law."

"Couldn't he have falsified his answers?" Baley was floundering, and knew it.

"Of course not. That is the difference between a robot and a man. A human brain, or any mammalian brain, cannot be completely analyzed by any mathematical discipline now known. No response can therefore be counted upon as a certainty. The robot brain is completely analyzable, or it could not be constructed. We know exactly what the responses to given stimuli must be. No robot can truly falsify answers. The thing you call falsification just doesn't exist in the robot's mental horizon."

"Then let's get down to cases. R. Daneel did point a blaster at a crowd of human beings. I saw that. I was there. Granted that he didn't shoot, wouldn't the First Law still have forced him into a kind of neurosis? It didn't, you know. He was perfectly normal afterward."

The roboticist put a hesitant hand to his chin. "That is anomalous."

"Not at all," said R. Daneel, suddenly. "Partner Elijah, would you look at the blaster that you took from me?"

Baley looked down upon the blaster he held cradled in his left hand.

"Break open the charge chamber," urged R. Daneel. "Inspect it." Baley weighed his chances, then slowly put his own blaster on the table beside him. With a quick movement, he opened the robot's blaster.

"It's empty," he said, blankly.

"There is no charge in it," agreed R. Daneel. "If you will look closer, you will see that there has never been a charge in it. The blaster has no ignition bud and cannot be used."

Baley said, "You held an uncharged blaster on the crowd?"

"I had to have a blaster or fail in my role as plain-clothes man," said R. Daneel. "Yet to carry a charged and usable blaster might have made it possible for me to hurt a human being by accident, a thing which is, of course, unthinkable. I would have explained this at the time, but you were angry and would not listen."

Baley stared bleakly at the useless blaster in his hand and said in a low voice, "I think that's all, Dr. Gerrigel. Thank you for helping out."

Baley sent out for lunch, but when it came (yeast-nut cake and a rather extravagant slice of fried chicken on cracker) he could only stare at it.

Round and round went the currents of his mind. The lines on his long face were etched in deep gloom.

He was living in an unreal world, a cruel, topsy-turvy world.

How had it happened? The immediate past stretched behind him like a misty improbable dream dating back to the moment he had stepped into Julius Enderby's office and found himself suddenly immersed in a nightmare of murder and robotics.

Jehoshaphat! It had begun only fifty hours before.

Persistently, he had sought the solution in Spacetown. Twice he had accused R. Daneel, once as a human being in disguise, and once as an admitted and actual robot, each time as a murderer. Twice the accusation had been bent back and broken.

He was being driven back. Against his will he was forced to turn his thoughts into the City, and since last night he dared not. Certain questions battered at his conscious mind, but he would not listen; he felt he could not. If he heard them, he couldn't help but answer them and, oh God, he didn't want to face the answers.

"Lije! Lije!" A hand shook Baley's shoulder roughly.

Baley stirred and said, "What's up, Phil?"

Philip Norris, Plain-clothes man C-5, sat down, put his hands on his knees, and leaned forward, peering at Baley's face. "What happened to you? Been living on knockout drops lately? You were sitting there with your eyes open and, near as I could make out, you were dead."

He rubbed his thinning, pale blond hair, and his close-set eyes appraised Baley's cooling lunch greedily. "Chicken!" he said. "It's getting so you can't get it without a doctor's prescription."

"Take some," said Baley, listlessly.

Decorum won out and Norris said, "Oh, well, I'm going out to eat in a minute. You keep it. - Say, what's doing with the Commish?"

"What?"

Norris attempted a casual attitude, but his hands were restless. He said, "Go on. You know what I mean. You've been living with him ever since he got back. What's up? A promotion in the works?"

Baley frowned and felt reality return somewhat at the touch of office politics. Norris had approximately his own seniority and he was bound to watch most assiduously for any sign of official preference in Baley's direction.

Baley said, "No promotion. Believe me. It's nothing. Nothing. And if it's the Commissioner you're wanting, I wish I could give him to you. Jehoshaphat! Take him!"

Norris said, "Don't get me wrong. I don't care if you get promoted. I just mean that if you've got any pull with the Commish, how about using it for the kid?"

"What kid?"

There was no need of any answer to that. Vincent Barrett, the youngster who had been moved out of his job to make room for R. Sammy, was shuffling up from an unnoticed corner of the room. A skull cap turned restlessly in his hands and the skin over his high cheekbones moved as he tried to smile.

"Hello, Mr. Baley."

"Oh, hello, Vince. How're you doing?"

"Not so good, Mr. Baley."

He was looking about hungrily. Baley thought: He looks lost, half dead - declassified.

Then, savagely, his lips almost moving with the force of his emotion, he thought: But what does he want from me?

He said, "I'm sorry, kid." What else was there to say?

"I keep thinking - maybe something has turned up."

Norris moved in close and spoke into Baley's ear. "Someone's got to stop this sort of thing. They're going to move out Chenlow now."

"What?"

"Haven't you heard?"

"No, I haven't. Damn it, he's a C-3. He's got ten years behind him."

"I grant that. But a machine with legs can do his work. Who's next?"

Young Vince Barrett was oblivious to the whispers. He said out of the depths of his own thinking, "Mr. Baley?"

"Yes, Vince?"

"You know what they say? They say Lynane Millane, the subethenics dancer, is really a robot."

"That's silly."

"Is it? They say they can make robots look just like humans; with a special plastic skin, sort of."

Baley thought guiltily of R. Daneel and found no words. He shook his head.

The boy said, "Do you suppose anyone will mind if I just walk around. It makes me feel better to see the old place."

"Go ahead, kid."

The youngster wandered off. Baley and Norris watched him go.

Norris said, "It looks as though the Medievalists are right."

"You mean back to the soil? Is that it, Phil?"

"No. I mean about the robots. Back to the soil. Huh! Old Earth has an unlimited future. We don't need robots, that's all."

Baley muttered, "Eight billion people and the uranium running out! What's unlimited about it?"

"What if the uranium does run out. We'll import it. Or we'll discover other nuclear processes. There's no way you can stop mankind, Lije. You've got to be optimistic about it and have faith in the old human brain. Our greatest resource is ingenuity and we'll never run out of that, Lije."

He was fairly started now. He went on, "For one thing, we can use sunpower and that's good for billions of years. We can build space stations inside Mercury's orbit to act as energy accumulators. We'll transmit energy to Earth by direct beam."

This project was not new to Baley. The speculative fringe of science had been playing with the notion for a hundred and fifty years at least. What was holding it up was the impossibility so far of projecting a beam tight enough to reach fifty million miles without dispersal to uselessness. Baley said as much.

Norris said, "When it's necessary, it'll be done. Why worry?"

Baley had the picture of an Earth of unlimited energy. Population could continue to increase. The yeast farms could expand, hydroponic culture intensify. Energy was the only thing indispensable. The raw minerals could be brought in from the uninhabited rocks of the System. If ever water became a bottleneck, more could be brought in from the moons of Jupiter. Hell, the oceans could be frozen and dragged out into Space where they could circle Earth as moonlets of ice. There they would be, always available for use, while the ocean bottoms would represent more land for exploitation, more room to live. Even carbon and oxygen could be maintained and increased on Earth through utilization of the methane atmosphere of Titan and the frozen oxygen of Umbriel.

Earth's population could reach a trillion or two. Why not? There was a time when the current population of eight billion would have been viewed as impossible. There was a time when a population of a single billion would have been unthinkable. There had always been prophets of Malthusian doom in every generation since Medieval times and they had always proven wrong.

But what would Fastolfe say? A world of a trillion? Surely! But they would be dependent on imported air and water and upon an energy supply from complicated storehouses fifty million miles away. How incredibly unstable that would be. Earth would be, and remain, a feather's weight away from complete catastrophe at the slightest failure of any part of the System-wide mechanism.

Baley said, "I think it would be easier to ship off some of the surplus population, myself." It was more an answer to the picture he had himself conjured up than to anything Norris had said.

"Who'd have us?" said Norris with a bitter lightness.

"Any uninhabited planet."

Norris rose, patted Baley on the shoulder. "Lije, you eat your chicken, and recover. You must be living on knockout pills." He left, chuckling.

Baley watched him leave with a humorless twist to his mouth. Norris would spread the news and it would be weeks before the humor boys of the office (every office has them) would lay off. But at least it got him off the subject of young Vince, of robots, of declassification.

He sighed as he put a fork into the now cold and somewhat stringy chicken.

Baley finished the last of the yeast-nut and it was only then that R. Daneel left his own desk (assigned him that morning) and approached.

Baley eyed him uncomfortably. "Well?"

R. Daneel said, "The Commissioner is not in his office and it is not known when he'll be back. I've told R. Sammy we will use it and that he is to allow no one but the Commissioner to enter."

"What are we going to use it for?"

"Greater privacy. Surely you agree that we must plan our next move. After all, you do not intend to abandon the investigation, do you?"

That was precisely what Baley most longed to do, but obviously, he could not say so. He rose and led the way to Enderby's office.

Once in the office, Baley said, "All right, Daneel. What is it?" The robot said, "Partner Elijah, since last night, you are not yourself. There is a definite alteration in your mental aura."

A horrible thought sprang full-grown into Baley's mind. He cried, "Are you telepathic?"

It was not a possibility he would have considered at a less disturbed moment.

"No. Of course not," said R. Daneel.

Baley's panic ebbed. He said, "Then what the devil do you mean by talking about my mental aura?"

"It is merely an expression I use to describe a sensation that you do not share with me."

"What sensation?"

"It is difficult to explain, Elijah. You will recall that I was originally designed to study human psychology for our people back in Spacetown."

"Yes, I know. You were adjusted to detective work by the simple installation of a justice-desire circuit." Baley did not try to keep the sarcasm out of his voice.

"Exactly, Elijah. But my original design remains essentially unaltered. I was constructed for the purpose of cerebroanalysis."

"For analyzing brain waves?"

"Why, yes. It can be done by field-measurements without the necessity of direct electrode contact, if the proper receiver exists. My mind is such a receiver. Is that principle not applied on Earth?"

Baley didn't know. He ignored the question and said, cautiously, "If you measure the brain waves, what do you get out of it?"

"Not thoughts, Elijah. I get a glimpse of emotion and most of all, I can analyze temperament, the underlying drives and attitudes of a man. For instance, it was I who was able to ascertain that Commissioner Enderby was incapable of killing a man under the circumstances prevailing at the time of the murder."

"And they eliminated him as a suspect on your say-so."

"Yes. It was safe enough to do so. I am a very delicate machine in that respect."

Again a thought struck Baley. "Wait! Commissioner Enderby didn't know he was being cerebroanalyzed, did he?"

"There was no necessity of hurting his feelings."

"I mean you just stood there and looked at him. No machinery. No electrodes. No needles and graphs."

"Certainly not. I am a self-contained unit."

Baley bit his lower lip in anger and chagrin. It had been the one remaining inconsistency, the one loophole through which a forlorn stab might yet be made in an attempt to pin the crime on Spacetown.

R. Daneel had stated that the Commissioner had been cerebroanalyzed and one hour later the Commissioner himself had, with apparent candor, denied any knowledge of the term. Certainly no man could have undergone the shattering experience of electroencephalographic measurements by electrode and graph under the suspicion of murder without an unmistakable impression of what cerebroanalysis must be.

But now that discrepancy had evaporated. The Commissioner had been cerebroanalyzed and had never known it. R. Daneel told the truth; so had the Commissioner.

"Well," said Baley, sharply, "what does cerebroanahysis tell you about me?"

"You are disturbed."

"That's a great discovery, isn't it? Of course, I'm disturbed."

"Specifically, though, your disturbance is due to a clash between motivations within you. On the one hand your devotion to the principles of your profession urges you to look deeply into this conspiracy of Earthmen who lay siege to us last night. Another motivation, equally strong, forces you in the opposite direction. This much is clearly written in the electric field of your cerebral cells."

"My cerebral cells, nuts," said Baley, feverishly. "Look, I'll tell you why there's no point in investigating your so-called conspiracy. It has nothing to do with the murder. I thought it might have. I'll admit that. Yesterday in the kitchen, I thought we were in danger. But what happened? They followed us out, were quickly lost on the strips, and that was that. That was not the action of well-organized and desperate men.

"My own son found out where we were staying easily enough. He called the Department. He didn't even have to identify himself. Our precious conspirators could have done the same if they had really wanted to hurt us."

"Didn't they?"

"Obviously not. If they had wanted riots, they could have started one at the shoe counter, and yet they backed out tamely enough before one man and a blaster. One robot, and a blaster which they must have known you would be unable to fire once they recognized what you were. They're Medievalists. They're harmless crackpots. You wouldn't know that, but I should have. And I would have, if it weren't for the fact that this whole business has me thinking in - in foolish melodramatic terms.

"I tell you I know the type of people that become Medievalists. They're soft, dreamy people who find life too hard for them here and get lost in an ideal world of the past that never really existed. If you could cerebroanalyze a movement as you do an individual, you would find they are no more capable of murder than Julius Enderby himself."

R. Daneel said slowly, "I cannot accept your statements at face value."

"What do you mean?"

"Your conversion to this view is too sudden. There are certain discrepancies, too. You arranged the appointment with Dr. Gerrigel hours before the evening meal. You did not know of my food sac then and could not have suspected me as the murderer. Why did you call him, then?"

"I suspected you even then."

"And last night you spoke as you slept." Baley's eyes widened. "What did I say?"

"Merely the one word 'Jessie' several times repeated. I believe you were referring to your wife."

Baley let his tight muscles loosen. He said, shakily, "I had a nightmare. Do you know what that is?"

"I do not know by personal experience, of course. The dictionary definition has it that it is a bad dream."

"And do you know what a dream is?"

"Again, the dictionary definition only. It is an illusion of reality experienced during the temporary suspension of conscious thought which you call sleep."

"All right. I'll buy that. An illusion. Sometimes the illusions can seem damned real. Well, I dreamed my wife was in danger. It's the sort of dream people often have. I called her name. That happens under such circumstances, too. You can take my word for it."

"I am only too glad to do so. But it brings up a thought. How did Jessie find out I was a robot?"

Baley's forehead went moist again. "We're not going into that again, are we? The rumor - "

"I am sorry to interrupt, partner Elijah, but there is no rumor. If there were, the City would be alive with unrest today. I have checked reports coming into the Department and this is not so. There simply is no rumor. Therefore, how did your wife find out?"

"Jehoshaphat! What are you trying to say? Do you think my wife is one of the members of - of..."

"Yes, Elijah."

Baley gripped his hands together tightly. "Well, she isn't, and we won't discuss that point any further."

"This is not like you, Elijah. In the course of duty, you accused me of murder twice."

"And is this your way of getting even?"

"I am not sure I understand what you mean by the phrase. Certainly, I approve your readiness to suspect me. You had your reasons. They were wrong, but they might easily have been right. Equally strong evidence points to your wife."

"As a murderess? Why, damn you, Jessie wouldn't hurt her worst enemy. She couldn't set foot outside the City. She couldn't..." - Why, if you were flesh and blood I'd - "

"I merely say that she is a member of the conspiracy. I say that she should be questioned."

"Not on your life. Not on whatever it is you call your life. Now, listen to me. The Medievalists aren't after our blood. It's not the way they do things. But they are trying to get you out of the City. That much is obvious. And they're trying to do it by a kind of psychological attack. They're trying to make life unpleasant for you and for me, since I'm with you. They could easily have found out Jessie was my wife, and it was an obvious move for them to let the news leak to her. She's like any other human being. She doesn't like robots. She wouldn't want me to associate with one, especially if she thought it involved danger, and surely they would imply that. I tell you it worked. She begged all night to have me abandon the case or to get you out of the City somehow."

"Presumably," said R. Daneel, "you have a very strong urge to protect your wife against questioning. It seems obvious to me that you are constructing this line of argument without really believing it."

"What the hell do you think you are?" ground out Baley. "You're not a detective. You're a cerebroanalysis machine like the electroencephalographs we have in this building. You've got arms, legs, a head, and can talk, but you're not one inch more than that machine. Putting a lousy circuit into you doesn't make you a detective, so what do you know? You keep your mouth shut, and let me do the figuring out."

The robot said quietly, "I think it would be better if you lowered your voice, Elijah. Granted that I am not a detective in the sense that you are, I would still like to bring one small item to your attention."

"I'm not interested in listening."

"Please do. If I am wrong, you will tell me so, and it will do no harm. It is only this. Last night you left our room to call Jessie by corridor phone. I suggested that your son go in your place. You told me it was not the custom among Earthmen for a father to send his son into danger. Is it then the custom for a mother to do so?"

"No, of cour - " began Baley, and stopped.

"You see my point," said R. Daneel. "Ordinarily, if Jessie feared for your safety and wished to warn you, she would risk her own life, not send her son. The fact that she did send Bentley could only mean that she felt that he would be safe while she herself would not. If the conspiracy consisted of people unknown to Jessie, that would not be the case, or at least she would have no reason to think it to be the case. On the other hand, if she were a member of the conspiracy, she would know, she would know, Elijah, that she would be watched for and recognized, whereas Bentley might get through unnoticed."

"Wait now," said Baley, sick at heart, "that's feather-fine reasoning."

There was no need to wait. The signal on the Commissioner's desk was flickering madly. R. Daneel waited for Baley to answer, but the latter could only stare at it helplessly. The robot closed contact.

"What is it?"

R. Sammy's slurring voice said, "There is a lady here who wishes to see Lije. I told her he was busy, but she will not go away. She says her name is Jessie."

"Let her in," said R. Daneel calmly, and his brown eyes rose unemotionally to meet the panicky glare of Baley's.