"I don't say even the thought of killing you, Daneel, was a pleasant one. He would have had R. Sammy do it, I imagine, if you didn't look so human that a primitive robot such as Sammy could not have told the difference, or understood it. First Law would stop him. Or the Commissioner would have had another human do it if he, himself, were not the only one who had ready access to Spacetown at all times.
"Let me reconstruct what the Commissioner's plan might have been. I'm guessing, I admit, but I think I'm close. He made the appointment with Dr. Sarton, but deliberately came early, at dawn, in fact. Dr. Sarton would be sleeping, I imagine, but you, Daneel, would be awake. I assume, by the way, you were living with Dr. Sarton, Daneel."
The robot nodded. "You are quite right, partner Elijah."
Baley said, "Then let me go on. You would come to the dome door, Daneel, receive a blaster charge in the chest or head, and be done with. The Commissioner would leave quickly, through the deserted streets of Spacetown's dawn, and back to where R. Sammy waited. He would give him back the blaster, then slowly walk again to Dr. Sarton's dome. If necessary, he would 'discover' the body himself, though he would prefer to have someone else do that. If questioned concerning his early arrival, he could say, I suppose, that he had come to tell Dr. Sarton of rumors of a Medievalist attack on Spacetown, urge him to take secret precautions to avoid open trouble between Spacers and Earthmen. The dead robot would lend point to his words.
"If they asked about the long interval between your entering Spacetown, Commissioner, and your arrival at Dr. Sarton's dome, you could say - let's see - that you saw someone lurking through the streets and heading for open country. You pursued for a while. That would also encourage them along a false path. As for R. Sammy, no one would notice him. A robot among the truck farms outside the City is just another robot.
"How close am I, Commissioner?"
Enderby writhed, "I didn't - "
"No," said Baley, "you didn't kill Daneel. He's here, and in all the time he's been in the City, you haven't been able to look him in the face or address him by name. Look at him now, Commissioner."
Enderby couldn't. He covered his face with shaking hands.
Baley's shaking hands almost dropped his transmitter. He had found it.
The image was now centered upon the main door to Dr. Sarton's dome. The door was open; it had been slid into its wall receptacle along its shining metal runner grooves. Down within them. There! There!
The sparkle was unmistakable.
"I'll tell you what happened," said Baley. "You were at the dome when you dropped your glasses. You must have been nervous and I've seen you when you're nervous. You take them off; you wipe them. You did that then. But your hands were shaking and you dropped them; maybe you stepped on them. Anyway, they were broken, and just then, the door opened and a figure that looked like Daneel faced you.
"You blasted him, scrabbled up the remains of your glasses, and ran. They found the body, not you, and when they came to find you, you discovered that it was not Daneel, but the early-rising Dr. Sarton, that you had killed. Dr. Sarton had designed Daneel in his own image, to his great misfortune, and without your glasses in that moment of tension, you could not tell them apart.
"And if you want the tangible proof, it's there!" The image of Sarton's dome quivered and Baley put the transmitter carefully upon the desk, his hand tightly upon it.
Commissioner Enderby's face was distorted with terror and Baley's with tension. R. Daneel seemed indifferent.
Baley's finger was pointing. "That glitter in the grooves of the door. What was it, Daneel?"
"Two small slivers of glass," said the robot, coolly. "It meant nothing to us."
"It will now. They're portions of concave lenses. Measure their optical properties and compare them with those of the glasses Enderby is wearing now. Don't smash them, Commissioner!"
He lunged at the Commissioner and wrenched the spectacles from the other's hand. He held them out to R. Daneel, panting, "That's proof enough, I think, that he was at the dome earlier than he was thought to be."
R. Daneel said, "I am quite convinced. I can see now that I was thrown completely off the scent by the Commissioner's cerebroanalysis. I congratulate you, partner Elijah."
Baley's watch said 24:00. A new day was beginning.
Slowly, the Commissioner's head went down on his arms. His words were muffled wails. "It was a mistake. A mistake. I never meant to kill him?" Without warning, he slipped from the chair and lay crumpled on the floor.
R. Daneel sprang to him, saying, "You have hurt him, Elijah. That is too bad."
"He isn't dead, is he?"
"No. But unconscious."
"He'll come to. It was too much for him, I suppose. I had to do it, Daneel, I had to. I had no evidence that would stand up in court, only inferences. I had to badger him and badger him and let it out little by little, hoping he would break down. He did, Daneel. You heard him confess, didn't you?"
"Yes."
"Now, then, I promised this would be to the benefit of Spacetown's project, so - Wait, he's coming to."
The Commissioner groaned. His eyes fluttered and opened. He stared speechlessly at the two.
Baley said, "Commissioner, do you hear me?"
The Commissioner nodded listlessly.
"All right, then. Now, the Spacers have more on their minds than your prosecution. If you co-operate with them - "
"What? What?" There was a dawning flicker of hope in the Commissioner's eyes.
"You must be a big wheel in New York's Medievalist organization, maybe even in the planetary setup. Maneuver them in the direction of the colonization of space. You can see the propaganda line, can't you? We can go back to the soil all right - but on other planets."