 What was thought to be used as an indication to settle the confusion between the crew and the two humans in moon-town?
Not only would there be life traces on that little moon, but it would be a lively place. Naturally they did not get results at once, nor did they expect to; it required a fine adjustment. But they were disappointed that they found nothing for several hours as they hovered high over the rotation. As though there were but one city, if that is its form. There was one more test to run, one very tricky and difficult of analysis, that with the Extraordinary Perception Locator. But this might be so varied or so unfamiliar that often both the machine and the designer of it were puzzled as to how to read the results. But when the Locator had refused to read Positive when turned on the inventor himself, bad blood developed between machine and man. It was for this reason that Glaser used that model no more, but built others more amenable. And it was for this reason also that the owners of Little Probe had acquired the original machine so cheaply. And there was no denying that the Extraordinary Perception Locator (or Eppel) was a contrary machine. On Earth it had read Positive on a number of crack-pots, including Waxey Sax, a jazz tootler who could not even read music. But it had also read Positive on ninety per cent of the acknowledged superior minds of the Earth. In space it had been a sound guide to the unusual intelligences encountered. He then narrowed to a smaller area (apparently one individual, though this could not be certain) and got very definite action. So among the intelligences there was at least one that might be extraordinary, though possibly in a crackpot way. Dawn did not come to the moon-town. The Little Probe hovered stationary in the light and the moon-town came up under the dawn. "Not a building, not two sticks or stones placed together. And those two ... why, they could well be Earth-people. Timidity has never been an efficacious tool with us." And one could only wish that all people were like them. There was a man and a woman, and they were clothed either in very bright garments or in no garments at all, but only in a very bright light. "And very little else," said Father Briton, "though that light trick does serve a purpose. The captain was a little puzzled by this, but he went on doggedly: "Ha-Adamah, what do you think that we are? "You are not anything till I name you.
 A game of checkers
 An inquisition about knowledge  A game of checkers  A contest of preternatural intellect  A physical test