Like most people who use computers but rarely think about them, I had not heard of Richard Stallman, and might never have if I hadn't tried to get into the Stata Center at MIT one day last fall. That's the postmodernist building, designed by Frank Gehry, that looks as if it's bursting apart at its metal seams.
Unfortunately, the front doors were locked tight.

"I can get you in," said a pleasant voice from somewhere behind me. I wheeled around and discovered a plump, wildly unkempt middle-aged man. My first thought was that he should be institutionalized. But then I remembered this was MIT, and he was probably some genius. "It will just take me a moment." He proceeded to pull from his pocket not a proper swipe card, but rather a strange gadget that looked like a miniature football wrapped in duct tape. He waved it slowly over the card reader, as if some magic were involved.

After about a minute, the doors clicked open, and he ushered me inside. We exchanged pleasantries, and then, a good 50 feet in, he turned to me and asked, "Now, why are you here?"

I explained I was interested in the building, which reassured him. "But how about you?" I asked. "Do you work here?"

He replied that he was Richard Stallman, head of the Free Software Foundation and the co-creator of the Linux operating system. He had an office upstairs.

"Then why don't you have a swipe card?"

A pause.

"I don't like them to track my movements."

Bill Gates and Paul Allen at Microsoft, Steve Jobs at Apple—these are the heads on the Mount Rushmore of computing. Yet there's also a fourth, forgotten man on the mountaintop, whose contribution perhaps exceeds the others'. The most momentous product of Stallman's genius, Linux, was the first operating system to feature software that was entirely free. That is, anyone could see its code, improve upon its applications, and copy it, gratis. Stallman's role in its creation is akin to building the Golden Gate Bridge single-handed. But his greatest achievement is that Linux soon became more than an operating system, mere competition to Microsoft's Windows or Apple's Mac OS. It became a computing philosophy. Its manifestations are everywhere; while you may not know it, you interact with it every day. Lawrence Lessig, a Stanford University law professor and former board member of the Electronic Frontier Foundation, a nonprofit that for nearly two decades has been at the vanguard of all things digital, says Stallman is a "visionary," and thinks that, in free software, he's behind nothing less than "the most important social movement of the 21st century."

The interesting thing about Stallman—and one reason he is the forgotten head on the mountain—is that he never sought to profit from Linux. Stallman detests wealth. That's why, upon entering the William H. Gates Building at MIT, he often turns to Gates's name on the wall and gives him the finger, vigorously, really shoving it up there. (When I observed this, he recruited me, a couple of graduate students, and a man I took to be a Korean tourist to do the same.) Making people buy a product that constrains their use of it would be anathema, because to Stallman freedom is more than an ideal; it is a code of conduct. It means being free to live outside society's norms and the government's vigilant eye, free to go where you please, without detection of any sort. Unlike the other forefathers of the computer industry, Stallman is not living off his one big idea. He is living out its ethos.

Of course, the pursuit of absolute freedom means Stallman sometimes acts a little weird, at least by any standard but his own. He travels the world as a free software evangelist for more than two-thirds of the year, and at last count had been to 65 countries. He has talked up free software at the Yale Political Union debate society, argued for it at the technology-related IADIS conference in Spain, and lobbied on behalf of its virtues with the president-elect of Ecuador.

When on the road, he carries exactly (and inexplicably) 52 pounds in his rolling suitcase, including an air mattress (to counter any hard beds), books, chocolate, tea, and roasted nuts. He lives off the meager stipends and paltry honoraria that come with his trips. "I've avoided the big expenses in life," he says proudly. He owns no real estate, no car, no TV, not even a bicycle (which he doesn't know how to ride). At this point, his most valuable possession is probably the laptop he received for free from the One Laptop Per Child initiative that grew out of MIT's Media Lab. He is generally assumed to live in his cramped office at MIT; Stallman's homemade business card—which he calls his "pleasure card"—gives the room as his address. He has use of it, at no charge, despite his lack of any official university appointment, because of his long associations and close colleagues there.

To avoid detection by "Big Brother"—a phrase he uses without irony—he tries to pay cash for everything; avoids Amtrak now that it demands the usual photo ID that Stallman, ever on the lookout for fascism, calls his "papers"; shuffles Charlie Cards with other people so that no single RFID (the radio-based ID system embedded in the cards) is linked to him; and, just in case, wraps Charlie in aluminum foil to mute the transmissions. Why would the MBTA care where he went? "I don't know why," Stallman replies, taken aback. "But they do. There's this philosophy of ‘Let's keep track of people absolutely as much as possible.'" And once they have it, they have it forever, he observes. "The record is permanent."

Stallman also owns no cell phone, but will borrow one, if need be. He says he's leery of the always-on GPS homing signal that some believe has allowed the CIA to off any number of Al Qaeda higher‑ups. "It's on even when the phone's off. You have to take the batteries out." He pauses. "I learned that from the Palestinian Information Technology Association. They have important reasons to know if their cell phones can tell where they are. They could get killed."

Of course, most of these precautions are pointless, since he outs himself every time he offers up ID to board a plane, then writes about every inch of his travels on his blog. So why bother with all the inconveniences?

"Fuck convenience," Stallman snaps. "If you won't sacrifice a little convenience for your freedom, you're going to lose it."