Reentering the ship they took it aloft and skimmed over Earth's surface, presently coming above a large city. A Terran would have recognized it as Chicago. Eye-stalks pressed to the quartz window, the alien pair scrutinized closely each building they passed over. "There's one!" exclaimed Koosh. He pointed with the longest three of his nine tendril-like appendages. "See it, Thuko?" "I see it. Yes, it is obviously empty of life and has been for some time. Set down the sphere, Koosh." Ten minutes later they were standing on a gravelled rooftop, sucking in more of the wonderful air of this hospitable world. "And so we begin our vacation on Earth," Koosh murmured softly, reverently. "A year, Thuko! a year of breathing this nectar ... of stuffing our poor starved bodies with fine foods unknown to Mars' barren soil. A year of abundance!" Vacation. The Martians had acquired, however dishonestly, the means of travel through interplanetary space, and could think of no better purpose for it than hauling them to vacations on Earth, a world they had long known to be rich in those things vital to life. Unfortunately for the masses of Mars, the sphere could only carry two passengers a trip, with one acting as pilot. Therefore its use had been strictly limited to high officials. Too bad for the masses; but lucky for Koosh and Thuko, since they both held important offices. They were merely the Shisti and Assistant Shisti, respectively. The Assistant Shisti spoke now, the round orifice in the center of his face rapidly dilating and contracting. Ignoring the other's ecstatic bubblings, he said, "This will be fine, Koosh. Little could happen to the ship here, unless the building collapsed. And of course we need not worry too much about the place remaining untenanted. That really makes small difference." * * * * * Koosh drooped his eye-stalks in agreement. "Except that the chances of accident would be increased somewhat. But now, let us leave here. This gravel punches through my sandal and hurts my foot." On the street, they paused to consider their next move. While they stood there debating, a seedy, stoop-shouldered human came shuffling along the walk and passed between them unheedingly, mumbling something about, "Need dough. Gotta get wine money...." The Shisti casually watched him out of sight around the corner, then said, "Astounding, Thuko, astounding. He gave no indication of having seen us. I must admit I don't completely understand it." "Who does?" countered Thuko. "It is something that science cannot satisfactorily explain. All the savants know is that most of these Earthlings do not believe in our existence, and somehow that nonbelief acts to prevent them from acknowledging the evidence of their senses that we are among them. Furthermore, wherever we go, if even one human in the immediate vicinity refuses to accept our reality, then we are apparent to none, though we stand before a thousand.