"Are you willing to let us give you a small dose--something less than the level given Harper and his men--and then tell us what you find out about it?" Nat Holt looked hesitant. "If you think you know what you're talking about. There's no point in my getting in a condition like Harper's." "We'll pull you out before you get anywhere near that far." Still dubious, he took a seat amid the mass of pulse generating equipment and electro-encephalograph recorders. A single pair of feedback terminals were fitted to his skull. The generator was set to duplicate his own feedback impulse taken from a moment of failure. Paul switched on the circuits and advanced the controls carefully. A look of pain and regret crossed Holt's face. He cried out with a whimper. "Turn it off!" "A second more--," Paul said. He advanced the control a hair and waited. The technologist began to cry suddenly in a low, sobbing voice. Paul cut the switch. For a moment Holt continued to slump in the chair, his shoulders jerking. Then he looked up, half-bewildered, half-furious. "What did you do to me?" he demanded. "You did it to yourself," Paul reminded him. "That's your own feedback pulse just beefed up a little, remember. How did it feel?" "Terrible! No wonder a guy dodges that. It's enough to make him wreck a space station to avoid the full blast of it." "What would you call it?" "I don't know--," Holt hesitated. "Grief, maybe. Regret--anxiety. But regret, mostly, I guess." "That's your feedback," Paul said as he removed the terminals and turned to the others. "These feedback pulses we've isolated are nothing but stabs of pure emotion." He turned with a faint smile to Holt. "You and Harper and the rest of the iron-bowelled boys were so convinced that the pure mechanical man would be utterly devoid of all emotional responses and content! And I was so sure that a warm, responsive, emotional human being could never respond like a cold machine! "And we were both utterly wrong. The human being does both. He operates on true cybernetic principles. But the content of his feedback control pulses is sheer emotion! "A small error, a stab of regret. It's repeated, magnified, or diminished until the action gets back on the track that brings predicted results. Ignored, the error builds up until the whole structure goes smash. "And we're _taught_ to ignore it! It's the noble, brave and manly thing to ignore the human feelings that surge through us. Be steel, be glass, be electrons--anything but a responsive, emotional human being! That's the way to be a superman! We've tried to find the way to perfection and have fought tooth and nail against the only means of achieving it."