* * * * * One by one, the top engineers of the Base went through the breakdown test. Some broke down with an emotional storm as Harper had, others simply ended in a swirl of confusion that put lights flashing all over the panels. But all of them had a breaking point of some kind that could be measured in a small number of hours. The test was a stab in the dark. It was based on an old and well-known principle that repeated tactile contact under command will break down the motor responses of the body in a matter of hours. Paul did not know whether it would actually provide a fertile lead to the problem of error or not, but it seemed the closest possible approach at present. Nat Holt, however, was astonished at the reaction of the men. He insisted on trying it himself, determined that he would not break down no matter what happened. He lasted six hours before the panel lit up like a Christmas tree. He subjected the resulting curves to an analyzer, and to his own he gave the most detailed attention. At the end of a full week of study on it, he called Paul with an excitement he could not suppress in his voice. "It looks like you owe that dinner," he said. "We've got what we were looking for!" "What are you talking about?" Paul demanded. "We've got proof that a human being is nothing more nor less than a simple cybernetic gadget. It's a laugh--people trying to build a mechanical man all these years. That's the only kind there is!" "You still aren't making sense." "Come on over and see for yourself." Puzzled and irritated, Paul left his office and went down to the analyzer laboratory. There he found Holt and his staff in a buzz of excitement. The multiple recorder sheets were laid out on long tables, being studied intensely. Paul followed Holt to one series that was separated from the rest. "We didn't know we had anything at first," said Holt. "The pulse was so low in amplitude that it was hard to pick out of the noise, but the analyzer showed it was consistently present under certain conditions of the subject." "What conditions?" said Paul. "At the exact moment of committing an error! I should say it occurs between the moment of making the decision to carry out an erroneous act and the triggering of the motor impulse that executes it." Paul frowned. "How can you be sure it doesn't occur at any other time as well?" "Because we've run every set of charts through the analyzer and this particular impulse comes out no other place." "It looks very interesting," Paul said. "But why did you say you've got proof that a human being is nothing but a cybernetic gadget? I don't see what this has got to do with it." "I didn't give you quite all the story," Holt said smugly. "I should have said that the pulse occurred every time there was an _intent_ to perform an error. Sometimes that intent was not carried out." "I don't understand."