It was a foolish thing to do, perhaps, but once The Guesser had set his mind on something, it took a lot more than a long walk to dissuade him from his purpose. He saw he was not the only spaceman out on the town; one of the Class Five taverns he passed was filled with boisterous singing, and he could see a crowd of men standing around three crewmen who were leading them in a distinctly off-color ballad. The Guesser smiled a little to himself. Let them have their fun while they were on-planet; their lives weren't exactly bright aboard ship. Of course, they got as much as was good for them in the way of entertainment, but a little binge gave them something to look forward to, and a good nerve-burning would sober them up fast enough if they made the mistake of coming back drunk. Nerve-burning didn't really bother a Five much, after all; they were big, tough, work-hardened clods, whose minds and brains simply didn't have the sensitivity to be hurt by that sort of treatment. Oh, they screamed as loud as anyone when they were in the burner, but it really didn't have much effect on them. They were just too thick-skulled to have it make much difference to them one way or the other. On the other hand, an Exec would probably go all to pieces in a burner. If it didn't kill him outright, he'd at least be sick for days. They were too soft to take even a touch of it. No Class One, so far as The Guesser knew, had ever been subjected to that sort of treatment, and a Two only got it rarely. They just weren't used to it; they wouldn't have the stamina to take it. His thoughts were interrupted suddenly by the familiar warning that rang in his mind like a bell. He realized suddenly, as he became blazingly aware of his surroundings, that he had somehow wandered into a definitely low-class neighborhood. Around him were the stark, plain housing groups of Class Six families. The streets were more dimly lit, and there was almost no one on the street, since it was after curfew time for Sixes. The nearest pedestrian was a block off and moving away. All that took him but a fraction of a second to notice, and he knew that it was not his surroundings which had sparked the warning in his mind. There was something behind him--moving. What had told him? Almost nothing. The merest touch of a foot on the soft pavement--the faintest rustle of clothing--the whisper of something moving through the air. Almost nothing--but enough. To a man who had played blindfold baseball, it was plenty. He knew that someone not ten paces behind him had thrown something heavy, and he knew its exact trajectory to within a thousandth of a millimeter, and he knew exactly how to move his head to avoid the missile. He moved it, at the same time jerking his body to one side. It had only been a guess--but what more did a Guesser need? From the first hint of warning to the beginning of the dodging motion, less than half a second had passed.