Doc did not turn his head.

Mack stood stunned. It is a frightening thing to lay out everything you have, to finish, and have no response. He didn’t know what to do next. He said loudly, “Doc!”

“Hello,” said Doc.

“Don’t you feel good?”

“Sure, Mack. How much do you want?”

“Two dollars.”

Doc reached in his hip pocket for his wallet without lifting his eyes. Mack’s great performance had been wasted. He might just as well have simply come in and asked for the money. He knew he could never reach such a height again. A sudden anger came over him, and he considered refusing the money, but his natural good sense saved him. He stood there rolling the dollar bills between his fingers. “What’s got into you, Doc?” he said.

Doc turned slowly toward him. “There’s going to be one great difficulty,” he said. “How am I going to light them? It’s always a problem, but in this case it might be insuperable.”

“Light what, Doc?”

“We start with two obvious problems,” Doc continued. “First, they can’t stand heat, and second, they are to a certain extent photophobic. I don’t know how I’m going to get enough cold light on them. Would it be possible, do you suppose, to condition them, to light them constantly, so that the photophobia subsides?”

“Oh sure,” said Mack uneasily.

“Don’t be too sure,” said Doc. “The very process of conditioning might, if it did not kill them, change their normal reactions. It’s always difficult to evaluate responses that approximate emotions. If I place them in an abnormal situation, can I trust the response to be normal?”

“No,” said Mack.

“You cannot dissect for emotion,” Doc went on. “If a human body were found by another species and dissected, there would be no possible way of knowing about its emotions or its thoughts. Now, it occurs to me that the rage, or rather the symptom that seems like rage, must be fairly abnormal in itself. I have seen it happen in aquariums. Does it occur on the sea bottom? Is the observed phenomenon not perhaps limited to the aquarium? No, I can’t permit myself to believe that, or my whole thesis falls.”