Attlebish interposed frigidly. “You are ignorant of the matter, Earthman. Whether we would or would not doesn’t matter. The fact is that Dr. Delmarre himself would not allow seeing, I assure you. If anyone came into his personal presence, regardless of how valued and long-standing a friendship there was between them, Dr. Delmarre would order him away and, if necessary, call robots to help with the ejection.”

“True,” said Baley, “if Dr. Delmarre were aware that personal presence was involved.”

“What do you mean by that?” demanded Dr. Thool in surprise, his voice quavering.

“When you treated Mrs. Delmarre at the scene of the murder,” replied Baley, looking full at his questioner, “she assumed you were viewing her, until you actually touched her. So she told me and so I believe. I am, myself, accustomed only to seeing. When I arrived at Solaria and met Security Head Gruer, I assumed I was seeing him. When at the end of our interview, Gruer disappeared, I was taken completely by surprise.

“Now assume the reverse. Suppose that for all a man’s adult life, he had been viewing only; never seeing anyone, except on rare occasions his wife. Now suppose someone other than his wife walked up to him in personal presence. Would he not automatically assume that it was a matter of viewing, particularly if a robot had been instructed to advise Delmarre that viewing contact was being set up?”

“Not for a minute,” said Quemot. “The sameness of background would give it away.”

“Maybe, but how many of you are aware of background now? There would be a minute or so, at least, before Dr. Delmarre would grow aware that something was wrong and in that time, his friend, whoever he was, could walk up to him, raise a club, and bring it down.”

“Impossible,” said Quemot stubbornly.

“I think not,” said Baley. “1 think opportunity must be canceled out as absolute proof that Mrs. Delmarre is the murderess. She had opportunity, but so might others.”

Baley waited again. He felt perspiration on his forehead, but wiping it away would have made him look weak. He must maintain absolute charge of the proceedings. The person at whom he was aiming must be placed in self-convinced inferiority. It was hard for an Earthman to do that to a Spacer.

Baley looked from face to face and decided that matters were at least progressing satisfactorily. Even Attlebish looked quite humanly concerned.

“And so we come,” he said, “to means, and that is the most puzzling factor of all. The weapon with which the murder was committed was never found.”

“We know that,” said Attlebish. “If it were not for that point, we would have considered the case against Mrs. Delmarre conclusive. We would never have required an investigation.”

“Perhaps,” said Baley. “Let’s analyze the matter of means, then.

There are two possibilities. Either Mrs. Delmarre committed the murder, or someone else did. If Mrs. Delmarre committed the murder, the weapon would have had to remain at the scene of the crime, unless it were removed later. It has been suggested by my partner, Mr. Olivaw of Aurora, who is not present at the moment, that Dr. Thool had the opportunity to remove the weapon. I ask Dr. Thool now, in the presence of all of us, if he did this, if he removed a weapon while examining the unconscious Mrs. Delmarre?”

Dr. Thool was shaking. “No, no. I swear it. I’ll abide any questioning. I swear I removed nothing.”

Baley said, “Is there anyone who wishes to suggest at this point that Dr. Thool is lying?”

There was a silence, during which Leebig looked at an object outside of Baley’s field of vision and muttered something about the time.

Baley said, “The second possibility is that someone else committed the crime and carried the weapon off with him. But if that were so, one must ask why. Carrying the weapon away is an advertisement of the fact that Mrs. Delmarre was not the murderess. If an outsider were the murderer, he would have to be a complete imbecile not to leave the weapon with the corpse to convict Mrs. Delmarre. Either way, then, the weapon—must be there! Yet it was not seen.”

Attlebish said, “Do you take us for fools or for blind men?”

“I take you for Solarians,” said Baley calmly, “and therefore incapable of recognizing the particular weapon that was left at the scene of the crime as a weapon.”

“I don’t understand a word,” muttered Klorissa in distress.

Even Gladia, who had scarcely moved a muscle during the course of the meeting, was staring at Baley in surprise.

Baley said, “Dead husband and unconscious wife were not the only individuals on the scene. There was also a disorganized robot.”

“Well?” said Leebig angrily.

“Isn’t it obvious, then, that, in having eliminated the impossible, what remains, however improbable, is the truth. The robot at the scene of the crime was the murder weapon, a murder weapon none of you could recognize by force of your training.”

They all talked at once; all but Gladia, who simply stared.

Baley raised his arms. “Hold it. Quiet! Let me explain!” And once again he told the story of the attempt on Gruer’s life and the method

by which it could have been accomplished. This time he added the attempt on his own life at the baby farm.

Leebig said impatiently, “I suppose that was managed by having one robot poison an arrow without knowing it was using poison, and having a second robot hand the poisoned arrow to the boy after telling him that you were an Earthman, without its knowing that the arrow was poisoned.”

“Something like that. Both robots would be completely instructed.”

“Very farfetched,” said Leebig.

Quemot was pale and looked as though he might be sick at any moment. “No Solarian could possibly use robots to harm a human.”

“Maybe so,” said Baley with a shrug, “but the point is that robots can be so manipulated. Ask Dr. Leebig. He is the roboticist.”

Leebig said, “It does not apply to the murder of Dr. Delmarre. I told you that yesterday. How can anyone arrange to have a robot smash a man’s skull?”

“Shall I explain how?”

“Do so if you can.”

Baley said, “It was a new-model robot that Dr. Delmarre was testing. The significance of that wasn’t plain to me until last evening, when I had occasion to say to a robot, in asking for his help in rising out of a chair, ‘Give me a hand!’ The robot looked at his own hand in confusion as though he thought he was expected to detach it and give it to me. I had to repeat my order less idiomatically. But it reminded me of something Dr. Leebig had told me earlier that day. There was experimentation among robots with replaceable limbs.

“Suppose this robot that Dr. Delmarre had been testing was one such, capable of using any of a number of interchangeable limbs of various shapes for different kinds of specialized tasks. Suppose the murderer knew this and suddenly said to the robot, ‘Give me your arm.’ The robot would detach its arm and give it to him. The detached arm would make a splendid weapon. With Dr. Delmarre dead, it could be snapped back into place.”

Stunned horror gave way to a babble of objection as Baley talked. His last sentence had to be shouted, and, even so, was all but drowned Out.

Attlebish, face flushed, raised himself from his chair and stepped forward. “Even if what you say is so, then Mrs. Delmarre is the murderess. She was there, she quarreled with him, she would be watching her husband working with the robot, and would know of the replaceable-limb situation—which I don’t believe, by the way. No matter what you do, Earthman, everything points to her.”

Gladia began to weep softly.

Baley did not look at her. He said, “On the contrary, it is easy to show that, whoever committed the murder, Mrs. Delmarre did not.

Jothan Leebig suddenly folded his arms and allowed an expression of contempt to settle on his face.