Back in the early 1980's, when I was living in the Sierra Foothills region of California about three hours' drive inland from San Francisco, I got invited to a summer study held at the Goddard Space Center in Maryland. It was attended by people from NASA, the academic world, various space-related industries, and a science-fiction writer. The object was to explore what roles computers might play in advanced space missions over the next twenty years and beyond. One of the topics considered was the concept of a self-replicating lunar factory. Essentially, the idea is to land a starter kit "seed" package on the lunar surface consisting of a factory system and robot workforce whose first task is to locate and deliver materials that the factory uses to produce more robots. When a critical size is reached, a migrant robot force relocates to commence construction of a second factory, a duplicate of the first. The pattern repeats in a multiplying progression until it becomes possible to divert surplus capacity into supplying the manufacturing needs of Earth from lunar resources. Analysis of the applicable numbers led to the astonishing conclusion that after twenty years the annual output could exceed the entire production of all Earth's present industries combined.
I had long been toying with something of a tongue-in-cheek story idea involving an upside-down world in which the "natural" inhabitants were machines and things like houses, tools, and other artifacts were organic, cultivated artificially by an intelligent, dominant species. But the problem I'd never been able to solve satisfactorily was, how it got started in the first place. It was only when I was on the plane back to California that I made the obvious connection: an advanced, alien, interstellar version of the lunar factory idea which somehow goes out of control. I started writing that very evening, and the Prologue to Code of the Lifemaker was completed by the end of the next day. A number of readers have written since to say that it alone was worth the price of the book.