These were ironic aspects Joe hadn't thought about before, just as he hadn't thought about the need to defend the Platform while it was being built. Defending it was Sally's father's job, and he wouldn't have a popular time. Joe wondered idly how Sally liked living out where the most important job on Earth was being done. She was a nice kid. He remembered appreciatively that she'd grown up to be a very good-looking girl. He tended to remember her mostly as the tomboy who could beat him swimming, but the last time he'd seen her, come to think of it, he'd been startled to observe how pretty she'd grown. He didn't know anybody who ought to be better-looking.... She was a really swell girl.... He came to himself again. There was a change in the look of the sky ahead. There was no actual horizon, of course. There was a white haze that blended imperceptibly into the cloud layer so that it was impossible to tell where the sky ended and the clouds or earth began. But presently there were holes in the clouds. The ship droned on, and suddenly it floated over the edge of such a hole, and looking down was very much like looking over the edge of a cliff at solid earth illimitably far below. The holes increased in number. Then there were no holes at all, but only clouds breaking up the clear view of the ground beneath. And presently again even the clouds were left behind and the air was clear--but still there was no horizon--and there was brownish earth with small green patches and beyond was sere brown range. At seventeen thousand feet there were simply no details. Soon the clouds were merely a white-tipped elevation of the white haze to the sides and behind. And then there came a new sound above the droning roar of the motors. Joe heard it--and then he saw. Something had flashed down from nowhere. It flashed on ahead and banked steeply. It was a fighter jet, and for an instant Joe saw the distant range seem to ripple and dance in its exhaust blast. It circled watchfully. The transport pilot manipulated something. There was a change in the sound of the motors. Joe followed the co-pilot's eyes. The jet fighter was coming up astern, dive brakes extended to reduce its speed. It overhauled the transport very slowly. And then the transport's pilot touched one of the separate prop-controls gently, and again, and again. Joe, looking at the jet, saw it through the whirling blades. There was an extraordinary stroboscopic effect. One of the two starboard propellers, seen through the other, abruptly took on a look which was not that of mistiness at all, but of writhing, gyrating solidity. The peculiar appearance vanished, and came again, and vanished and appeared yet again before it disappeared completely. The jet shot on ahead. Its dive brakes retracted. It made a graceful, wallowing, shallow dive, and then climbed almost vertically. It went out of sight.