question:  Why was the cave the only place that was not visited?
context: EVERYTHING IT HAD WAS IN THE GARDEN BY R. A. LAFFERTY 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. 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. On Earth it had read Positive on a number of crack-pots, including Waxey Sax, a jazz tootler who could not even read music. 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. They called it the "You tell me light." So among the intelligences there was at least one that might be extraordinary, though possibly in a crackpot way. If we find no others then we will go down boldly and visit this." 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. 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. It was water, but water that excelled, cool and with all its original bubbles like the first water ever made. I don't understand that light that surrounds them.
output:  The serpent lives there and the crew was told that he was cranky.
options:  The cave was only a reflective illusion from the bright light.  The crew ran out of time but planned to examine it upon their next arrival  Adam, or Ha-Adamah, told the crew that it was much to dangerous as there were evil creatures living inside.  The serpent lives there and the crew was told that he was cranky.