Sometime in the past Benton had read a story about a telepath who was balked in his effort to read the hero's mind when that worthy assiduously worked mental arithmetic problems. His surface thoughts being carefully under control, and clearly readable, the man was able to plan a course of action against the telepath, undetected. In the story it had worked, but that Urei could be baffled in such a way, Benton doubted. However it was the only defense he could think of, and worth a try. For hours he pondered, hoping that the numerous circuit equations he worked and solved would appear to Urei's inquiring mind to be a legitimate intellectual occupation in the middle of the night. He had little faith that Urei lacked the power to read those submerged thoughts, once he realized that the stronger ones were a mask. It was the latter thought which made Benton feel butterflies in the pit of his stomach so persistently that they seemed to have become permanent residents in his abdominal cavity. Twice he thought he was sufficiently fatigued to sleep; but when he tried to compose himself Benton found his thoughts dwelling too strongly on his plans, and he had to return to his equations. A shower and fresh linen worked a partial restoration but Benton knew that his vitality was at a low ebb when he finally sallied forth in the morning sunshine. Yet he was fortified with a certain amount of satisfaction that his night's work had not been wasted. He had a plan, and he was certain that it would not be recognized as such by Urei, no matter how thoroughly his mind was probed. Benton had worked it out in snatches, never allowing it to crystallize as a whole; yet he was certain that it would unfold itself in appropriate action once he started it going. No one but he, or perhaps Dr. Albie, could have devised such a plan. Its beauty lay in the fact that all the steps required were things he might do in the normal discharge of his duties. All but one--and that one Benton wouldn't allow himself to think about. Yet when the steps had been taken, they would be irreversible. Not only to Urei, but to all the scientists and technicians who tended the machine; there would never be another Urei, at least not in this century. Even on the way to his work, the one place in the world where he must carefully guard his thoughts, Benton's mind refused to leave the subject. But perhaps that was to the good. For while he doubted that Urei would be fooled by his working of circuit equations, it would be perfectly safe to be occupied mentally with certain phases of the situation. The business of Urei's independence of his mechanical appurtenances, for instance: Benton could dwell on that with safety, for Urei would expect him to be shocked by the information.