Dawn bolted deer-like over the black hills of Ganymede, and as if it had never interrupted its work, the distant sun beat down upon the frozen landscape with renewed vigor. A lone earth figure rolled over and groaned. Shakily it got to its feet and took a few trembling steps. John Hall, exhausted physically and mentally was all right again. The madness of the preceding night had left him, almost as suddenly as it had come upon him. It was almost as if kind nature had blotted out the portion of his brain which preserved memory, and left his mind, dulled, numb. In a daze, his once proud figure tripped along the devious mountain passes. Too tired to leap--barely capable of moving, John Hall threaded his tortuous way through regions only half recalled. No thoughts, simply a guiding instinct that urged him, warned him, that he must go this way to return to the space ship, and food--maybe rescue. And a hundred yards behind him, unnoticed, trailed multiple, black, ungainly creatures, who stumbled when he stumbled, fell when he fell. It was nearing twilight again when John Hall panted back into the region of his space ship. Barely cognizant of what he was doing, he smashed a can of beans against the steel hull of the ship and devoured them without ceremony, animal-like. Then he sat wearily down upon a ruined metal bench and tried to relax. Weakly, but nevertheless desperately, he fought with himself. Trying to clear the cobwebs that cluttered up his brain and reason rationally again. Thoughts, like flitting ghosts, aroused tantilizingly, only to whisk down some hidden channel of his mind before he could fully grasp and comprehend them. One of the grotesque things, creatures, objects, whatever they were, drew close to him, its bulging eyes peering not inquisitively, but _fearfully_ into his. He knew! The eluding coherency of thought came. The answer to the enigma lay in his own mind! His powerful earth mind. Scientists had always been aware that the mind radiates energy thoughts away from it. That one mind is capable of hypnotizing another, even across great distances. These inhabitants of Ganymede, with their acute mental receptivity, were slaves to his more powerful will--his every thought. And against their own desires they followed and imitated him. And through some unknown chemical reaction even took the form, momentarily, of some wished-for object. It was clear. But now again it wasn't. His mind was failing. Falling back into the abyss of blackness and incoherency! He stared a moment at one of the peculiar faces before him and as he stared it changed, grew smooth, black, ebony black--and God--blank! Blank like his mind--part of his mind, for through the rest of it swirled a fantasmagoria of images, and disconnected phrases. He was alone, or almost so. Those things were still here. It was getting darker ... colder ... so cold ... was this all a dream? Then he stopped! For over the blank face of the thing in front of him flickered