Philip K. Dick : The Variable Man: He was a man from the past. And he could fix things.

Philip K. Dick wrote some great Science Fiction and here is an example. Published in 1953, in Space Science Fiction, this story explores an earth that is rigidly bound both by centuries of single minded focus on war, and on what happens when humans have learned to depend entirely on a mechanical calculator/computer to tell them what to do. There is no room for a factor outside known factors, something to throw all calculations off. A man from the past. He fixed things—clocks, refrigerators, vidsenders and destinies. But he had no business in the future, where the calculators could not handle him. He was Earth’s only hope—and its sure failure!