There were twenty-five or thirty passengers wedged into the middle section of the train, all standing in slightly cramped postures and most of them unsmiling. I knew exactly how they felt. Not being able to get a seat in an off-hour in the evening can be irritating. But right at the moment there was no room in my mind for annoyance. A slow, hard-to-pin-down uneasiness was creeping over me again, as if a pendulum were swinging back and forth somewhere close to me, ticking out a warning in rhythm--and I couldn't shut out the sound of it. Just my over-strained nerves, of course. How could it have been anything else? I turned and looked at the man standing next to me. He was middle-aged, conservatively dressed, and had a square-jawed, rather handsome face, with a dusting of gray at his temples. He was frowning slightly and his expression didn't change when I broke the rule of silence which was customarily observed in the Underground. "No reason for all the seats to be gone at this hour," I said. The crazy kind of over-exuberance mixed with peevishness that makes some people say things like that to total strangers a dozen times a day had always seemed inexcusable to me. But when you're under tension you sometimes break all the habits of rational behavior you've imposed on yourself in small matters. My excuse was that I simply wanted to test the firmness and steadiness of my own voice, to make sure that, deep down, I wasn't nearly as apprehensive as I was beginning to feel. "Yes, I know," the gray-templed man agreed. "It burns me up a little too. But I guess it just can't be helped at times. Operating an Underground this size must be an awful train-scheduling headache." "Headache or not," I said. "There's no excuse for it." He smiled abruptly, exposing large, white teeth and I noticed that there was something almost birdlike in the way his eyes lighted up. Small, black, very bright eyes they were, under short-lashed lids, and quite suddenly he made me think of a magpie alighting on a limb, taking off and alighting again, hardly able to restrain an impulse to chatter. "What it boils down to," he said, "is the old quarrel between a pedestrian and a man in a car. Neither can understand or sympathize with the other's point of view. Fifteen million people ride this Underground every day and to them it's a poor slob's service at best. That's because they feel themselves to be the victims, at the receiving end. But you've got to remember that safety precautions pose a problem. Avoiding accidents comes first and the New Chicago Transportation System, considering its colossal size, does pretty well in that respect."