Richard Stallman, a software advocate affiliated with MIT, doesn’t really wear hats, but he’s been known to don tinfoil. In 2005, while attending a U.N. technology summit in Tunisia, he received a photo badge with a radio-frequency identification chip. Disgusted, he purchased a roll of aluminum foil, covered his badge, and handed sheets out to others. Tunisian security nearly blocked him from giving his talk. “By covering our badges,” he later noted, “we could prevent our movements within the summit, and our movements outside, from being scanned; we could also make a visible protest against the surveillance society that many governments are trying to impose.” A fellow delegate blogged that Stallman had “a legitimate gripe, handled with Richard’s usual highly visible, guileless, and absolutely unsubtle style of nonviolent protest.”

Stallman has been concerned about digital privacy since the 1990s, but it’s just one of the many issues (alongside censorship, copyright, and others) that motivate his push to shake up the software landscape. He aims for the world to use only “free” software (“think ‘free speech,’ not ‘free beer’”) whose source code can be freely studied, altered, and shared by its users. Nearly all the software on our phones and computers, as well as on other machines, is nonfree or “proprietary” software and is riddled with spyware and back doors installed by Apple, Google, Microsoft, and the like. In the 1980s, Stallman started a movement to support free software. In the process, he and others created a free operating system, GNU, currently running on tens of millions of computers, including nearly every web server. If you’ve heard of open source (free software’s practice sans its moral stance) or Linux (really GNU, plus a program called Linux), you can thank Stallman.

By using proprietary software, Stallman believes, we are forfeiting control of our computers, and thus of our digital lives. In his denunciation of all nonfree software as inherently abusive and unethical, he has alienated many possible allies and followers. But he is not here to make friends. He is here to save us from a software industry he considers predatory in ways we’ve yet to recognize.

Richard Stallman is a hacker’s hacker—in skills, , and temperament. For a while he lived in his lab. He doesn’t use keycards to unlock doors for of being tracked. He deploys puns mercilessly. He often carries a recorder (the musical instrument) in his pocket to play when the mood strikes him. His emails begin with this boilerplate: “To any NSA and FBI agents reading my email…” He’s received a MacArthur “genius” grant and 15 honorary doctorates.

To appreciate Stallman’s message, you have to look past his personal quirks—one online video shows him answering audience questions while picking something off his bare foot—but to understand how someone has achieved what he has, it helps to look at the whole person. So I visited him at MIT, where he has worked since the early 1970s. I reached the elaborate–Frank Gehry–designed home of MIT’s Computer Science and Laboratory (CSAIL), and Stallman padded downstairs to meet me in black dress socks, brown Dockers, and a burgundy polo shirt stretched over his belly, before leading me back up to a table outside his third-floor office, which was off limits but revealed tight shelves packed to the ceiling with books and CDs.

Talking with Stallman is a little unnerving at first. He has piercing olive eyes that don’t look away, even during long pauses between points. To determine when he has finished speaking and is ready for another question requires patience and close ; beware making the wrong call (“Please let me tell the story!”). He bites his nails, picks his teeth, and perpetually fiddles with and chews on the split ends of his long, graying hair.

A few minutes into our conversation, a student returns to his laptop at the table. Stallman eyes the offending Mac. “That’s a horrible ,” he tells the young man. “That’s a nonfree operating system. It tramples your freedom just by being there.” Stallman explains that the operating system he helped birth can be swapped in. “I hope you will escape from Apple’s power.”

He began writing this OS in 1984, calling it GNU, pronounced with a hard and recursively short for “GNU’s Not Unix.” He wanted a free alternative to Unix, and soon afterward founded the Free Software Foundation (FSF) to support its collaborative development. Free software adheres to four main principles: Users must be able to use it however they want, to study its source code, to share it, and to share modified versions. They can sell copies if they want, as long as they meet the other criteria. Stallman often calls proprietary software “user-subjugating software.”

At GNU.org, Stallman documents the ways in which nonfree software installed in phones, laptops, cars, and elsewhere controls its users. It can spy on them. Corporations can restrict which software or hardware is compatible with it. Back doors allow companies to install or modify programs or data. Corporations can censor content. Software includes bugs or security holes that users aren’t allowed to fix. Nor can users add new features or remove unwanted ones. Most poetically, Amazon once remotely deleted purchased—but unauthorized—copies of George Orwell’s 1984 from customers’ Kindles (or, says Stallman, “Swindles”).

By 1991, most of GNU’s critical pieces were finished when a young programmer in Finland named Linus Torvalds wrote the last essential part of the OS, a piece called the “kernel.” This kernel became known simply as Linux, and eventually the whole GNU/Linux package became known as Linux, even though by a couple of counts the lines of GNU code outnumbered those of Linux ten-to-one. To secure Stallman’s participation in this article, I agreed to call the operating system “GNU/Linux.” Stallman insists on this name, both to give credit to the GNU programmers and to maintain focus on the principles of freedom that drove its development.

At MIT, I asked the Mac-using student what he knew about Stallman and free software. He had some familiarity but made the critical mistake of referring to “open source” software. (I also promised to adhere to Stallman’s requirement to call such software “free” instead of “open source.”) “Calling it ‘open source,’” Stallman told him, “is a way that people who disagree with me try to cause the ethical issues to be forgotten.” In 1998, a faction of the free software movement split off. This subgroup liked the idea of sharing and collaborating on code, but did it for practical reasons, not principled ones. They wanted a term other than “free,” both because they didn’t mean to imply that the alternative was unjust, and also because “free” confused people (“free beer”), so they settled on “open source.”

“One of the reasons I don’t use the name ‘free software,’” Torvalds told me, is that “that whole ‘freedom’ thing comes with too much emotional baggage. You can’t discuss things rationally.” Eric Raymond, who cofounded the Open Source Initiative in 1998, says, “The free software crowd sound like moralists.” He argues that the best way to change most people’s behavior is “not to try to mess with their value premises,” but to offer practical incentives; they’ll then self-supply new values to rationalize their new behavior.

But for Stallman, moralism is the whole point. If you write or use free software only for practical reasons, you’ll stop when it’s inconvenient, and freedom will disappear.

I first heard Stallman speak 15 years ago at MIT. On entering the lecture hall, he exchanged heated words with the host, then began yelling and flailing his arms. He would not let his talk be webcast using RealPlayer, because that would have imposed the use of a proprietary program on his home viewers. “Why are you being so obstinately obtuse?” he demanded. “Why do you insist on not understanding what I’m telling you?” Once RealPlayer was off the table and some people had left out of discomfort, he gave the lecture—on the “Draconian restriction” known as copyright. A one-time use of RealPlayer seems a harmless convenience, but “if I don’t show that I take my principles seriously,” he told the audience, “I can’t expect anybody else to take them seriously.”

When yelling at a lecture host or insisting on the name GNU/Linux, Stallman may seem like an entitled child, but “Richard has very little in the way of personal ego,” Raymond says. “What he has is a commitment to his ideas that is utterly total. And it’s very important to him that people not only behave in the way he wants them to behave but think in the way he wants them to think.” He summarizes: “Most of the community respect Richard but don’t buy all of his premises.”

Stallman is used to his premises going unsold. He grew up in New York City, interested in math, science, and history. He was reading calculus textbooks by age 7 and later enjoyed math puzzles and model rockets, according to his biography, Free as in Freedom—written by Sam Williams in 2002 and revised by Stallman eight years later. In middle school he used an IBM manual to write computer programs on paper. Others made fun of him, even in the Columbia Science Honors Program that he attended on Saturdays. “It hurt horribly when I was teased,” he says.

While he’s since grown a thicker skin, as a child he found little solace with his parents. “I thought of my parents as tyrants,” he says. “And I resented their power.” I asked if that was simply because of his disregard for authority or if other parents might have been more agreeable. He couldn’t be sure. “Although I’ve seen families that get along with each other, it’s almost incomprehensible for me.” It wasn’t until he settled into his residential house at Harvard, as a physics undergraduate, that he felt as if he had a home.

During his freshman year, he was searching Cambridge for interesting computers to study and landed at MIT’s AI lab, where he found a second home—among its hackers. (“Hacking” was an MIT term applied to various kinds of playful cleverness.) The lab’s ethos was formative. For instance, they didn’t write security code for the lab’s machines because it could be used against them. “They decided not to put chains around their necks and hand them to the administrators,” Stallman says.

There was also an unofficial policy of not locking your office at night if it contained a computer terminal that others might need. Unobliging faculty members led Stallman to become something of a cat burglar, by way of Robin Hood. Upon arrival at the lab, he was shown a makeshift battering ram they’d used to open locked doors. Other hackers sometimes lifted the ceiling tiles and climbed over the wall and down into offices, but the fiberglass would make their skin itch for days. Stallman devised a method of lifting just a couple of tiles and lowering a loop of tape to lasso and turn the inside doorknob. “The place had a unique free spirit at that time,” Stallman recalls. They subverted rules, but only in the service of communal . “I found that powerfully inspiring.”

After graduating from Harvard in 1974, Stallman began a graduate degree in physics at MIT. But a year later, he injured his knee and could no longer participate in regular folk dancing, his great joy, as well as his one way of meeting women. (He has never married but currently has a girlfriend.) “That took all the joy out of my life,” he says. “I just collapsed in misery.” He lost his to study physics and dropped out, but he saw ways he could be useful with programming and continued to work in the AI lab.

Around 1980, an incident occurred that has become something of his origin story as a movement leader. Xerox had given MIT a laser printer, and Stallman hoped to hack it to prevent paper jams. MIT hadn’t received the source code, so Stallman visited a programmer at Carnegie Mellon who had worked on the machine. But when he asked for the code, the man refused, citing a nondisclosure agreement. Stallman was so stunned, he left the man’s office without saying a word. “I couldn’t think of a thing to say that would do justice to it,” he says. “And I didn’t want to treat him with the normal courtesy I would for a decent person.” The betrayal provoked the next step in his ideological evolution. “All my experiences at MIT taught me how nice it was to be in a place with free software. But the printer incident helped me to see that nonfree software was actually an injustice.”

Stallman the moralistic freedom-fighter often obscures the rest of his character. I asked Eben Moglen—a law professor at Columbia, the FSF’s general counsel, and a collaborator with Stallman for a quarter century—what people might not know about him. “He has a winsome and childlike ,” he says. There’s that recorder he carries around, and a button he made in the 1970s and still wears that says “Impeach God.” He also sometimes carries zero-dollar bills, which he uses to bribe people, including passport agents. As Stallman says, “It’s legally valid and any U.S. agency will give you zero dollars in gold for it.” He gave one to Barney Frank hoping he’d vote no on the Digital Millennium Copyright Act, which bans breaking digital restrictions . (Frank voted yes, and Stallman “lost all respect for him.” Plus Frank kept the cash.)

Wordplay entertains Stallman endlessly. When I visited MIT he said he’d just come up with the best joke of his life, about Theresa May, the British prime minister, who has a history of backing surveillance: “They put up a sculpture of Theresa May, and everyone in the area thought it was watching them. So someone attacked it with a hammer and was fined ‘statue Tory’ damages.” Puns plus are Stallman’s sweet spot. (He then quoted the Labour politician Aneurin Bevan: “The Tories are lower than vermin.” That one has less of a ring to it.)

Moglen shared a story from 2006, when a large number of people in the free software movement were meeting at MIT to discuss the latest version of the GNU Public License, or GPL. The GPL, first released in 1989, is the text that people attach to free software projects to keep them free. It basically says that you can’t make the code proprietary, and if it’s used in another project, then that project can’t be made proprietary either. It’s a brilliant use of the copyright system: All code automatically falls under copyright, but those who own a copyright can dictate how their material is used. Typically they insert terms specifying that the material cannot be modified or distributed without their permission. But in a jiu-jitsu move, Stallman inserted terms specifying that such “do not copy” terms cannot be inserted, thus keeping the software and its descendants free forever. The GPL is perhaps the greatest hack of Stallman’s life. Others have since applied similar copyright terms to books, music, and art, a practice now known as “copyleft.”

So, Moglen says, this GPL meeting was “the beginning of a carefully plotted process we had spent a year getting ready for.” They’d printed several hundred copies of the discussion draft and were ready to hand them out and simultaneously release the document online. But in the previous version, Stallman had included in the support material a reference to a fictional CEO named Ty Coon. Someone judged the name politically incorrect and changed it. Stallman noticed the switch backstage, and said he would have to denounce the license. “And so we’re standing there, everybody absolutely dumbfounded and terrified,” Moglen says. “I thought to myself, How could it be complete, after all these years of work and careful preparation, how could it be more appropriately complete than by Richard Stallman coming in and denouncing his own work?” He talked Stallman out of his obstinacy, but Stallman told me, “That is the way I’m likely to react to someone who tries to censor my jokes.”

Moglen recalled another story, about a speech Stallman gave in India. He was on stage before thousands of people with the chief minister of Kerala, an Indian state of 35 million, as well as academics and dignitaries. At the end of the day, when it was time for Stallman’s climactic address, he stood up and said it was too hot and he was too tired and he would speak the next morning. “I thought, in a sense, we were in exactly the right part of the world for him to do this,” Moglen says, “because Richard was another holy man who had his own way of doing things.”

And yet Stallman likes to mock that holy man persona with a character he calls St. IGNUcius of the Church of Emacs. (Emacs is a text editor he wrote that’s earned devotion from its users.) At the end of many of his talks, he dons a robe and a halo made of a large computer disc and recites a litany of free software jokes bridging technology and theology.

For another perspective on Stallman’s character, his friend and fellow hacker Michele Metts says, “He’s one of the few people I know who does the right thing. He is not fearful of being an outsider.” He’s also “the kindest, gentlest human being.” I had tried to picture him as a parent and asked him about kids. He never wanted them, but he said, “I sometimes have more maternal than paternal feelings toward a child.” How so? “I think of paternal as being harsh”—perhaps because his father drank and verbally abused his stepmother—“and these feelings are just a matter of kindness and concern. I wouldn’t express them by saying, ‘No, no, no.’” (He clarifies that his frequent admonishments to others are matters of concerned advisory, not force.)

For a thorough look at Stallman’s way of life, you might skim his lecture rider, which makes Van Halen’s request for no brown M&M’s look inattentive to detail. This 9,000-word document, drawing from past mishaps, specifies everything from the topic and length of the talk, to the temperature he prefers when , to the foods and music he dislikes (egg yolk, rock), to what words to avoid saying, to how to screen reporters for interviews, to the method in which to book his hotel (don’t use his name, and in any case he prefers someone’s couch as it’s more fun). He specifies that he likes parrots, but please don’t buy one for him, and (to avoid a third such incident) certainly don’t buy a captured wild parrot: “Meeting that sad animal is not an agreeable surprise.” He also makes it clear that you should not “offer help all the time,” especially when it comes to breakfast (“Please just do not bring it up”) or crossing the street (“Please just leave me alone when I cross streets”).

I mentioned the rider as we chatted, and he explained that people with “rigid politeness programming” prevent things from getting done. “You can see I have a very low opinion of politeness,” he says, between split ends. “It has little in common with consideration.”

Despite the dislikes listed on his rider, Stallman is an adventurous eater and a connoisseur of Chinese food. At MIT, Metts picked us up and drove us to Chinatown for dinner. Metts is about Stallman’s age (he’s 63), African-American with greying dreadlocks, and a 28-year veteran of punk and metal bands. She wore hot pink sunglasses, and they exchanged impromptu puns as we crossed the bridge into Boston. Stallman, on users of the mobile game Pokémon Go, which tracks players: “They’ve been put in the pokey.” He notes that all cellphone users can be tracked, however, which is one reason he doesn’t carry one.)

And more puns at dinner, before digging into a plate of baby leeks, Stallman says, “We should honor Snowden when we eat this dish.” Edward Snowden has already honored Stallman. On a trip to London, Stallman was invited for a social chat by Julian Assange, the head of WikiLeaks, to the Ecuadorian embassy, where he’s taking refuge. During the visit, Assange read aloud an appreciative greeting from the whistleblower.

Stallman used to come to Chinatown late at night with his fellow MIT hackers—until they stopped inviting him, a snub presaging a bitter rivalry among his colleagues, what he calls “the civil war.” In telling the story of his own life, Stallman points to three books. The first is the saga of Njál, an Icelander who became embroiled in a feud and was burned to death in his home. The second is the true story of Ishi, a Native American who became the last of his tribe when his family was killed. The third is Floating Worlds, a science fiction novel about a woman who defiantly remains on Earth after its inhabitants are forced to leave. All evoke a destructive period in his life, one that led to great creation but still haunts him. “The experience of losing my community changed me,” he says over dinner, “and I’m scared that people will reject me.”

Around 1980, two companies, Symbolics and LMI, were spun out of the AI lab to sell computers called Lisp machines. Stallman didn’t like that his friends spent less time in the lab. For a while, the two companies and MIT shared code, but in 1982 Symbolics stopped sharing, hoping to run the smaller LMI out of business. They compelled each MIT user to choose a side; to punish that, Stallman chose the side against Symbolics. “What they had done was a betrayal that destroyed the last of my home,” he says between dumplings. Metts pipes in: “And I thought punk rock was treacherous.”

In his outrage, Stallman spent nearly two years single-handedly re-creating (and sometimes besting) every new Symbolics feature in the MIT code, keeping LMI alive. The feat astounded his fellow software designers. As Moglen, FSF’s attorney, told me, “Richard Stallman, like Isaac Newton, is a great focused thinker, with a mind like a nuclear furnace that can melt down anything.” Eventually Stallman saw there was no future in Lisp machines and decided to do something constructive rather than vengeful. “And that’s GNU,” he says. “But the fact that I had succeeded in outdoing all of my former colleagues together gave me the great strength of that I could do a very big project.”

Don't confuse all Stallman's ambition for . He never expected the free software movement to make such progress, and he can’t name an uplifting book to accompany the tragic trio describing his life. “The world is getting worse and worse, in regard to freedom in general,” he says, “and in regard to how computing treats people,” by deleting their books, and so on. But his stance on pronouns is instructive. “I absolutely will not use they as singular,” he told me. “It fills me with revulsion. I will not stand for it.” Instead he sometimes uses person, per, and pers, following the writer Marge Piercy. When asked if he sees these options catching on, he says, “If you give up on trying to promote something because it hasn’t already caught on, you’re surrendering to a self-fulfilling prophesy.”

So he stands nearly alone in his absolute dedication to free software, expressing at those who make nonfree software and pity or frustration at the “fools” who use it (you and me). In various ways I pushed the argument that some people have different values and should be allowed to trade freedom for convenience if they choose. There’s no free equivalent of the iPhone. He says the fact that an agreement is voluntary doesn’t mean it’s legitimate—look at feudalism—and argues that we need inalienable rights to avoid oppression. Using nonfree software will eventually hurt you (by exposing you to manipulation), and it perpetuates a norm that hurts others. Users “don’t see the connection between what they’re doing and the pain that results,” he says, “but I do.”

We’re short-term thinkers, Stallman says. “Do you remember when Microsoft said, ‘Where do you want to go today?’ I said, ‘How do you want to live in five or 10 years?’ That’s our question.” I expressed that a free software community could ever match the rich software ecosystem powered by capitalism. He shared my pessimism, but says, “So what? That ‘rich ecosystem’ is no substitute for freedom.”

Stallman is unforgiving in his rhetoric, “but he is also a man who understands that there are complexities of human motivations,” Moglen says. “So let us assume that Richard’s language may be blunt, but I would not necessarily conclude that the idea behind it is quite so un-nuanced.” He adds, “It is still, however, judgmental.” As I paid for dinner with a credit card, Stallman thanked me but encouraged me to use cash. I cited skepticism that a record of the meal would be used against me, plus the convenience and flier miles that come with plastic. To which he switched from “politeness” to (I guess) consideration and asked me, “How easily can you be bought?”

Stallman cares about surveillance because he sees it as a threat to democracy. Here’s the logic: The state holds secrets. To control the state, citizens need those secrets. To obtain them, we need whistleblowers. But surveillance lets the state identify and imprison whistleblowers. Thus, he says: “Democracy depends on reducing the level of general surveillance to the point where the state cannot identify the whistleblowers.” In that statement, he says, “I claim to have presented a theorem about the maximum level of surveillance that is compatible with democracy.”

Puns and a fake halo may not supply enough honey to draw the masses to Stallman’s cause, given the general acridity of his sermonizing. But he travels most of the year, giving talks around the world. (His position at MIT carries no responsibilities. He doesn’t even program anymore—because, he says, “I have been involuntarily self-promoted into management. That’s meant to be a joke.”) He’s still in demand, and, whether you find him charming or shrill, his ideas remain vital.

As Moglen told me, he’s made some great software, written some great licenses, and created a small foundation. “But the idea of copyleft and the proposition that social and political freedom can’t happen in a society without technological freedom—those are his long-term meanings. And humanity will be aware of those meanings for centuries, whatever it does about them.”

Matthew Hutson is a science writer and author of The 7 Laws of Magical Thinking.

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