Benton's eyes brightened a little. No amount of letdown could entirely extinguish his scientific curiosity, and this was a mystery he had to solve. "But you've been operating.... The entire building was powered with this pile. Even the lights...." There was a mental chuckle. "Sub-cosmic energy does it. I had the technicians hook it up years ago. It's more dependable, also more plentiful, as well as free. Man will discover its use in a few generations, I imagine. Now, my fine friend, if you're temporarily over your murdering rampage, suppose you return to the control room. There's some interesting stuff coming over the television, if you turn it on." * * * * * Benton was suddenly aware that the gong had ceased to sound. The defective tube had been replaced and Urei was once again operating. There was no sign of commotion when he came upon his men; they were working on the new circuits, just as he had left them. "Keep going," he said to the foreman. "If you get stuck, I'll be in the control room. Otherwise keep using the same plans we used this morning." "We ought to clean up by four," the man answered. Benton once more heard that chuckle which wasn't quite audible. "Gotta hand it to you," Urei said. "You've got a well-trained crew." "Yes," thought Benton. "Except that when you boss them, they don't make reports of their work." "I guess you're talking about this energy-rectifier I just told you about. It wouldn't have paid to let them remember what they made. After all, your science doesn't know enough to understand what it is, or how it works. Also it would have given me away. Don't worry, you'll catch up to it in another generation or six." "_I'm_ wise to you," Benton reminded. "Why not tell me? It would do humanity a lot of good, you know. And you're supposed to be helping humanity, if I remember correctly." There was a barely noticeable hesitation. Then: "Let's not discuss it now. I haven't quite made up my mind concerning policy of that sort. I'm still adhering to my rule of answering any question that's asked, within the scope of the knowledge which has been fed to me by man. That leaves your progress up to yourself. And incidentally, I did a little monkeying today which has nothing to do with policy; it was strictly a matter of self-preservation. You'll see what I mean when you turn to that video set." Benton had entered the control room. He leaned over and fumbled with a shoe lace. "In a minute. You said you _guessed_ I was talking about the energy-rectifier, whatever that is. Didn't you know? Weren't you reading my mind? In fact, weren't you reading it all along and saw through my efforts to disguise my thoughts?"