But the most awe-inspiring and, to Lee, foreboding sights, were the "C.P.F.'s" as the guards called them, the "Critical-Parts-Factories." On a superficial glance they looked ordinary modern plants: staggered rows of machine tools sprouting from the main stem of the assembly line. There was the familiar din of steel, the piercing screeches of the multiple drills, the heavy pantings of the hydraulic presses. But after a minute or so the visitors felt a vague uneasiness and then the realization dawned that there was something missing and that this something was human life. "Aren't there even machine tenders or supervisors? Isn't there _anybody_?" "Not a soul," the answer came. "It's all automatic. Full automatic down here." They stared at the end of the assembly line; every twenty seconds it spit out a fractional horsepower motor onto a transport band which nursed the newborn engine into the rows of testing machines. * * * * * The elevator brought them back to the communication center where the Terminal Cafeteria was ablaze with lights and where Dr. Scriven, received his honored guests. The guests were seated after the manner of a French restaurant, all in one row, and as they raised expectant faces in the direction of the service entrance "Gog and Magog" entered the room carrying trays with refreshments which they served with the skill and the dignity of accomplished waiters. Gog and Magog were products of two assembly lines down in the Thorax. Robots, still in an experimental stage, yet of remarkable perfection. Both of them were about human size and approximately human-shaped but the design of the two was different. Gog, the "light-duty" robot, balanced itself by a gyroscope on a pair of stumpy legs, while the "heavy-duty" Magog crawled noiselessly and rapidly on caterpillar rubbertracks like a miniature tank. Of both types the arms were uncommonly long and simian-like, but the remarkable progress made in the engineering of prothesis after the Second World War had lent them perfect articulation and sensitivity down to the last hydraulically operated fingerjoint. The photoelectric cells of their eyes looked pale and repulsive; the square audion-screens of their ears however made up for that by the comical precision with which they turned in every direction at the sound of a commanding human voice. Their understanding of any given order appeared perfect. "Congratulations, Dr. Scriven, you've got the country's servant problem licked at last." "I wonder whether one could buy one and how much he would be?" "First waiter who ever came when I called him." "What a butler Gog would make, the perfect Jeeves. Could he learn to answer the phone?" "I bet he would even make a fourth at bridge." "Magog, the check please." "See, how he understands. He shakes his head; he says it's on the house." "Let's try to tip him: Gog, here's fifty cents for you; no he won't take it."