Donovan left him, keeping the secret of his identity. When he returned to his home he looked in the mirror, and the face of a rose-cheeked 20-year-old youngster stared back at him. Fifty years of happy living in the 20th century! It would soon be necessary to return to the 25th century so that Blascomb could reverse the antibiotic catalytic process that had set him growing younger. It was impossible to stay in his present youthful state much longer. In a few years he would be a child.
With a sigh he walked to his desk, took out paper and pen, and began to draw the diagrams for the apparatus which would send him forward into the 25th century.
For three hours he worked confidently, and then the sweat began to drip from his forehead and his heart began to pound fearfully. "It is not possible," he said, uneasily. "It will all come back to me soon. Now what the devil did Blascomb tell me?"
He had become lazy, and his brain was not used to hard work. He said this to himself but he could not shake off the sense of fear. He took a cold shower, rubbing himself briskly, then shot a stimulant into his blood stream. Preparing the desk once more, he began to work.
The papers gathered, the pencils broke, and the night gradually turned to morning. The finished sketch of the cycle travellers was basically correct, but the most important operating mechanism was still missing. Try as he could, he was unable to bring it up from his memory.
"By the solar system," he swore, "what is the matter with me? I have forgotten every detail."
He tried to think back. At one time he had known the mechanism thoroughly. As an engineer he was completely familiar with every single plate and tube, but now he couldn't remember anything but the general appearance of the finished machine. Fear spurred his mind as he hunted for a solution. Something was happening to his mind. He began to think of his stories. The same thing had happened there. At one time he remembered every detail of life in the 25th century, and could describe them easily. Now events were dim and he knew now why his recent stories were poor. They were not written from actual memory of the future, but were the ordinary stories one might expect from a 20-year-old boy. The past was dim and memory faded. Blascomb and Crane, Crane and Blascomb, which was the C.D. agent, and what was C.D. anyway?
Enough of the details remained to shock him into an awareness of his desperate plight. The rejuvenation process had worked too well, for Donovan had waited dangerously long. As the body grew younger the tissue cells were consumed and youthful cells replaced them. The process that had worked for body cells did the same for the cells of the brain. Those portions of the brain containing the knowledge and ability of a 70-year-old man were gradually being replaced with new, untrained cells. He had failed to re-educate himself as new cells replaced the old, and had come to the brink of disaster. Sufficient intelligence and manual dexterity remained to compensate for that, but in a few years the task would be hopeless.
Excitedly, for he knew his life depended on it, he rummaged through his book shelves looking for a copy of his first story, "Turn Backward, O Time!" It contained, he remembered, a concise, accurate description of the mechanism for the time-machine. The magazine itself was old, the sheets turning brown and the pages breaking. He read the story in haste, vaguely remembering the plot. The actual description of the operating mechanism, he found to his consternation, was missing. "I will cut one or two paragraphs," the editor had said, "They are not convincing, technically ... they lack verisimilitude!"