There was another question I wanted to ask of McGuire. "McGuire, you are not supposed to allow Mr. Oak to come to any harm. Yet you did so. Why?" I was wondering how he'd managed to let Brentwood get away with his attack on me, without at least warning me.

"Mr. Oak was in no danger, sir. He has come to no harm."

"What about Brentwood's attack?"

"Mr. Brentwood did not attack Mr. Oak, sir; Mr. Oak attacked Mr. Brentwood."

The other three looked at me. "In a way, he's right," I said quickly. "When I saw Brentwood standing there with the hypospray, I jumped him."

"That's another one of our problems," said Felder. "How do you define 'harm'? If you broke your arm and a doctor tried to set it without an anesthetic, what would McGuire think when you yelled? Could you and I engage in a friendly boxing match? And since McGuire is supposed to prevent harm, he has to be able to define it in advance. Oh, we've had a lot of fun with that one, I'll tell you." There was a thin edge of bitterness in his voice.

"You see what this means, don't you?" Videnski asked, eying me through a cloud of blue cigarette smoke.

"Sure," I whispered. "It means that McGuire will go right on accelerating until I tell him to stop, and I can't tell him that until my larynx heals—if it ever does."

"If it takes a week or two, which is likely," Vivian said, "we'll be saying good-by to the Solar System."

"By the time this heals," I said, "we'll be so far out we won't be able to come back. At that distance, the amount of sunlight McGuire will be able to pick up will be negligible, and the atomic fuel will be gone."