"I take it Earth is useless as a source of supply."
"Unfortunately, that is so, sir. Our positronic brains are as sensitive to radioactivity as human proteins are."
"You use the plural, and this mansion before us seems, large, beautiful, and elaborate-at least as seen from the outside. There are then other beings on the moon. Humans? Robots?"
"Yes, sir. We have a complete ecology on the moon and a vast and complex hollow within which that ecology exists. The intelligent beings are all robots, however, more or less like myself. You will see none of them, however. As for this mansion, it is used by myself only and it is an establishment that is modeled exactly on one I used to live in twenty thousand years ago."
"Which you remember in detail, do you?"
"Perfectly, sir. I was manufactured, and existed for a time-how brief a time it seems to me, now-on the Spacer world of Aurora."
"The one with the-" Trevize paused.
"Yes, sir. The one with the dogs."
"You know about that?"
"Yes, sir."
"How do you come to be here, then, if you lived at first on Aurora?"
"Sir, it was to prevent the creation of a radioactive Earth that I came here in the very beginnings of the settlement of the Galaxy. There was another robot with me, named Giskard, who could sense and adjust minds."
"As Bliss can?"
"Yes, sir. We failed, in a way, and Giskard ceased to operate. Before the cessation, however, he made it possible for me to have his talent and left it to me to care for the Galaxy; for Earth, particularly."
"Why Earth, particularly?"
"In part because of a man named Elijah Baley, an Earthman."
Pelorat put in excitedly, "He is the culture-hero I mentioned some time ago, Golan."
"A culture-hero, sir?"
"What Dr. Pelorat means," said Trevize, "is that he is a person to whom much was attributed, and who may have been an amalgamation of many men in actual history, or who may be an invented person altogether."
Daneel considered for a moment, and then said, quite calmly, "That is not so, sirs. Elijah Baley was a real man and he was one man. I do not know what your legends say of him, but in actual history, the Galaxy might never have been settled without him. In his honor, I did my best to salvage what I could of Earth after it began to turn radioactive. My fellow-robots were distributed over the Galaxy in an effort to influence a person here-a person there. At one time I maneuvered a beginning to the recycling of Earth's soil. At another much later time, I maneuvered a beginning to the terraforming of a world circling the nearby star, now called Alpha. In neither case was I truly successful. I could never adjust human minds entirely as I wished, for there was always the chance that I might do harm to the various humans who were adjusted. I was bound, you see-and am bound to this day-by the Laws of Robotics."
"Yes?"
It did not necessarily take a being with Daneel's mental power to detect uncertainty in that monosyllable.
"The First Law," he said, "is this, sir: 'A robot may not injure a human being or, through inaction, allow a human being to come to harm.' The Second Law: 'A robot must obey the orders given it by human beings except where such orders would conflict with the First Law.' The Third Law: 'A robot must protect its own existence, as long as such protection does not conflict with the First or Second Law.'Naturally, I give you these laws in the approximation of language. In actual fact they represent complicated mathematical configurations of our positronic brain-paths."
"Do you find it difficult to deal with those Laws?"
"I must, sir. The First Law is an absolute that almost forbids the use of my mental talents altogether. When dealing with the Galaxy it is not likely that any course of action will prevent harm altogether. Always, some people, perhaps many people, will suffer so that a robot must choose minimum harm. Yet, the complexity of possibilities is such that it takes time to make that choice and one is, even then, never certain."
"I see that," said Trevize.
"All through Galactic history," said Daneel, "I tried to ameliorate the worst aspects of the strife and disaster that perpetually made itself felt in the Galaxy. I may have succeeded, on occasion, and to some extent, but if you know your Galactic history, you will know that I did not succeed often, or by much."
"That much I know," said Trevize, with a wry smile.
"Just before Giskard's end, he conceived of a robotic law that superseded even the first. We called it the 'Zeroth Law' out of an inability to think of any other name that made sense. The Zeroth Law is: 'A robot may not injure humanity or, through inaction, allow humanity to come to harm.' This automatically means that the First Law must be modified to be: 'A robot may not injure a human being, or, through inaction, allow a human being to come to harm, except where that would conflict with the Zeroth Law.' And similar modifications must be made in the Second and Third Laws."
Trevize frowned. "How do you decide what is injurious, or not injurious, to humanity as a whole?"
"Precisely, sir," said Daneel. "In theory, the Zeroth Law was the answer to our problems. In practice, we could never decide. A human being is a concrete object. Injury to a person can be estimated and judged. Humanity is an abstraction. How do we deal with it?"
"I don't know," said Trevize.
"Wait," said Pelorat. "You could convert humanity into a single organism. Gaia."
"That is what I tried to do, sir. I engineered the founding of Gaia. If humanity could be made a single organism, it would become a concrete object, and it could be dealt with. It was, however, not as easy to create a superorganism as I had hoped. In the first place, it could not be done unless human beings valued the superorganism more than their individuality, and I had to find a mind-cast that would allow that. It was a long time before I thought of the Laws of Robotics."