Ralph, sitting on the roof of his tower, was oblivious to all about him. He was unable to dismiss from his mind the lovely face of the girl whose life he had just been the means of saving. The soft tones of her voice were in his ears. Heretofore engrossed in his work, his scientific mind had been oblivious to women. They had played no part in his life. Science had been his mistress, and a laboratory his home. And now, in one short half hour, for him the whole world had become a new place. Two dark eyes, a bewitching pair of lips, a voice that had stirred the very core of his being-- Ralph shook himself. It was not for him to think of these things, he told himself. He was but a tool, a tool to advance science, to benefit humanity. He belonged, not to himself, but to the Government--the Government, who fed and clothed him, and whose doctors guarded his health with every precaution. He had to pay the penalty of his +. To be sure, he had everything. He had but to ask and his wish was law--if it did not interfere with his work. There were times he grew restive under the restraint, he longed to smoke the tobacco forbidden him by watchful doctors, and to indulge in those little vices which vary the monotony of existence for the ordinary individual. There were times when he most ardently wished that he were an ordinary individual. He was not allowed to make dangerous tests personally, thereby endangering a life invaluable to the Government. That institution would supply him with some criminal under sentence of death who would be compelled to undergo the test for him. If the criminal were killed during the experiment, nothing was lost; if he did not perish, he would be imprisoned for life. Being a true scientist, Ralph wanted to make his own dangerous experiments. Not to do this took away the very spice of life for him, and on occasion he rebelled. He would call up the Planet Governor, the ruler of 15 billion human beings, and demand that he be relieved of his work. "I can't stand it," he would protest. "This constraint which I am forced to endure maddens me, I feel that I am being hampered." The Governor, a wise man, and a kindly one, would often call upon him in person, and for a long time they would discuss the question, Ralph protesting, the Governor reasoning with him. "I am nothing but a prisoner," Ralph stormed once. "You are a great inventor," smiled the Governor, "and a tremendous factor in the world's advancement. You are invaluable to humanity, and--you are irreplaceable. You belong to the world--not to yourself." Many times in the past few years he recalled, had the two been over the same ground, and many times had the diplomatic Governor convinced the scientist that in sacrifice of self and devotion to the world's future lay his great reward. The voice of his manservant interrupted his reverie. "Sir," he said, "your presence in the transmission-room would be appreciated."