[David Owen is a staff writer for the New Yorker and the author of"Copies in Seconds," a history of the Xerox machine.]

Like most modern investigative bodies, the 9/11 commission did much of its work by studying documents — roughly 2.5 million pages' worth of them. The vast majority of those documents were produced (and then, during the course of the investigation, repeatedly reproduced) by a remarkable process that is so much a part of our lives we no longer think of it as remarkable. That process is xerography, and it is responsible for the vast majority of the printed pages that most of us handle in the course of an ordinary working day because it is the basis not only of virtually all office copiers but also of laser printers.

People often assume that xerography must be related to conventional photography, but it's not. It is based on an obscure combination of photoconductivity and electrostatics — a combination so unlikely that the man who conceived it, a shy, humble patent attorney named Chester Carlson, spent years trying to find anyone who would take him seriously. Carlson came up with his idea in 1937 while reading a technical journal in the New York Public Library, then pitched it to IBM, RCA, Bell & Howell, General Electric and Eastman Kodak, among many others; all responded with what Carlson would describe later as"an enthusiastic lack of interest." So persistent was this failure of capitalistic vision that by the time the first true xerographic office copier went into production in 1960, Carlson's original patent had expired (he had others).

The company that created that epochal machine was a little-known manufacturer of photographic supplies that was originally called the Haloid Co.; since 1961, it has been known as Xerox Corp.

My kids, who were born in the '80s and have never known a time when copying someone else's notes for a test was more bothersome than walking across the room and pressing a button, view our home copier, a Xerox XC1045, with about as much awestruck wonder as they view our washing machine. Only with a heroic exertion of sympathetic brain power can they imagine what life must have been like in the days when copying an interesting news story consisted of calling your grandmother and asking her if she had already thrown away her newspaper.

When I needed a copy of my sixth-grade science fair report, back in the mid-1960s, my mother sent the original to work with my father, whose employer had one of the early Xerox machines. My father's access to that machine (or, rather, his access to the secretary who was the machine's sole authorized operator) was another of the semi-supernatural powers he possessed as a result of wearing a suit and working downtown. Yet, to my children, this all seems like something out of"Little House on the Prairie."

Xerographic copiers have been around for less than 50 years, and laser printers for little more than 30, yet xerography has had a huge effect on human communication, comparable to that of Gutenberg's printing press. It has given ordinary people a simple means of reproducing and sharing printed information, and, by doing so, it has reduced the ability of the strong to keep secrets from the weak. (Without photocopying, there could have been no Pentagon Papers, for example.) A telling indication of xerography's significance is that in the former Soviet Union, whose rulers maintained their power in part by monopolizing access to information, copiers were guarded more closely than computers, and individual copies were numbered so that they could be traced....