"Close up it had a corrugated, hoary look, as if it had bubbled up out of the ground when the moon had a molten crust and been fused into a mound by fire and earthquake. "But when I halted directly in front of it I saw that it wasn't as solid as it looked. It was riddled with little dark holes, as though a woodpecker had spent at least a month making a wreck of it. And at its base there was a wide, dark, tunnel-like opening. "Another man might have thought of a hundred excuses for not crawling through that tunnel on his hands and knees. But when my curiosity is aroused I'm a very special kind of idiot. "The tunnel was about twenty feet in length. I crawled along through the darkness with my atomic blaster slapping against my hip, my heart hammering against my ribs. "When the smothering feeling you get in tunnels began to wear thin I knew that it would be safe for me to stand up. You can feel a stone wall arching above you without touching it, and I knew suddenly that I was in the clear. "When I got to my feet and stared about me I could see the dark end of the tunnel and what appeared to be stone walls hemming me in. The walls arched away into shadows, and were faintly luminous. "I've spent as many hours underground as there are seeds in a watermelon--so I can take a cave interior in my stride. But the mound wasn't just hollow and cavelike and filled with wavering shadows. It was--occupied! "He was sitting on a projecting ledge in deep shadows. But the wall behind him glowed, and I could see him clearly. He was wearing a space-suit exactly like my own, but it was all shriveled up over him. "Take a little monkey--a lemur or a spectral tarsier will do--and put him inside a cumbersome space-suit, and let his bright eyes shine out through the viewpane. Do that--and you'll have as clear a picture of him as I could give you if I rambled on for ten minutes. "I couldn't see the little fellow's face through the pane. It was all a shadowy blue. But I could see his bright eyes, and I could tell he was little by the way the suit overlapped, and bulged out in the wrong places. "You know how a kid of eight or ten looks when he puts on a man's suit on Hallowe'en? But this wasn't Hallowe'en, and he wasn't trying to scare anyone! "He was too scared himself. He was shaking all over and when he saw me his eyes got even brighter, and he started to get up. He was trembling so I had to help him to his feet. "I steadied him with one arm and lifted off the helmet with my free hand. As you know, you can stay outside a suit on the moon without getting frost-bitten for about half a minute. "When his face came into view and his eyes looked straight into mine I was so startled that fifteen seconds were lost right at the start--before a single word could be exchanged between us. But at least I had a chance to get a good look at him.