The master wears an amulet with a blue eye in the center. Before him, a candidate kneels in the candlelit room, surrounded by microscopes and surgical implements. The year is roughly 1746. The initiation has begun.

The master places a piece of paper in front of the candidate and orders him to put on a pair of eyeglasses. "Read," the master commands. The candidate squints, but it's an impossible task. The page is blank.

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The candidate is told not to panic; there is hope for his vision to improve. The master wipes the candidate's eyes with a cloth and orders preparation for the surgery to commence. He selects a pair of tweezers from the table. The other members in attendance raise their candles.

The master starts plucking hairs from the candidate's eyebrow. This is a ritualistic procedure; no flesh is cut. But these are "symbolic actions out of which none are without meaning," the master assures the candidate. The candidate places his hand on the master's amulet. Try reading again, the master says, replacing the first page with another. This page is filled with handwritten text. Congratulations, brother, the members say. Now you can see.

For more than 260 years, the contents of that page—and the details of this ritual—remained a secret. They were hidden in a coded manuscript, one of thousands produced by secret societies in the 18th and 19th centuries. At the peak of their power, these clandestine organizations, most notably the Freemasons, had hundreds of thousands of adherents, from colonial New York to imperial St. Petersburg. Dismissed today as fodder for conspiracy theorists and History Channel specials, they once served an important purpose: Their lodges were safe houses where freethinkers could explore everything from the laws of physics to the rights of man to the nature of God, all hidden from the oppressive, authoritarian eyes of church and state. But largely because they were so secretive, little is known about most of these organizations. Membership in all but the biggest died out over a century ago, and many of their encrypted texts have remained uncracked, dismissed by historians as impenetrable novelties.

It was actually an accident that brought to light the symbolic "sight-restoring" ritual. The decoding effort started as a sort of game between two friends that eventually engulfed a team of experts in disciplines ranging from machine translation to intellectual history. Its significance goes far beyond the contents of a single cipher. Hidden within coded manuscripts like these is a secret history of how esoteric, often radical notions of science, politics, and religion spread underground. At least that's what experts believe. The only way to know for sure is to break the codes.

In this case, as it happens, the cracking began in a restaurant in Germany.

For years, Christiane Schaefer and Wolfgang Hock would meet regularly at an Italian bistro in Berlin. He would order pizza, and she would get the penne all'arrabbiata. The two philologists—experts in ancient writings—would talk for hours about dead languages and obscure manuscripts.

It was the fall of 1998, and Schaefer was about to leave Berlin to take a job in the linguistics department at Uppsala University, north of Stockholm. Hock announced that he had a going-away present for Schaefer.

She was a little surprised—a parting gift seemed an oddly personal gesture for such a reserved colleague. Still more surprising was the present itself: a large brown paper envelope marked with the words top secret and a series of strange symbols.

Schaefer opened it. Inside was a note that read, "Something for those long Swedish winter nights." It was paper-clipped to 100 or so photocopied pages filled with a handwritten script that made no sense to her whatsoever:

Arrows, shapes, and runes. Mathematical symbols and Roman letters, alternately accented and unadorned. Clearly it was some kind of cipher. Schaefer pelted Hock with questions about the manuscript's contents. Hock deflected her with laughter, mentioning only that the original text might be Albanian. Other than that, Hock said, she'd have to find her own answers.

A few days later, on the train to Uppsala, Schaefer turned to her present again. The cipher's complexity was overwhelming: symbols for Saturn and Venus, Greek letters like pi and gamma, oversize ovals and pentagrams. Only two phrases were left unencoded: "Philipp 1866," written at the start of the manuscript, and "Copiales 3" at the end. Philipp was traditionally how Germans spelled the name. Copiales looked like a variation of the Latin word for "to copy." Schaefer had no idea what to make of these clues.

She tried a few times to catalog the symbols, in hopes of figuring out how often each one appeared. This kind of frequency analysis is one of the most basic techniques for deciphering a coded alphabet. But after 40 or 50 symbols, she'd lose track. After a few months, Schaefer put the cipher on a shelf.

Thirteen years later, in January 2011, Schaefer attended an Uppsala conference on computational linguistics. Ordinarily talks like this gave her a headache. She preferred musty books to new technologies and didn't even have an Internet connection at home. But this lecture was different. The featured speaker was Kevin Knight, a University of Southern California specialist in machine translation—the use of algorithms to automatically translate one language into another. With his stylish rectangular glasses, mop of prematurely white hair, and wiry surfer's build, he didn't look like a typical quant. Knight spoke in a near whisper yet with intensity and passion. His projects were endearingly quirky too. He built an algorithm that would translate Dante's Inferno based on the user's choice of meter and rhyme scheme. Soon he hoped to cook up software that could understand the meaning of poems and even generate verses of its own.

Knight was part of an extremely small group of machine-translation researchers who treated foreign languages like ciphers—as if Russian, for example, were just a series of cryptological symbols representing English words. In code-breaking, he explained, the central job is to figure out the set of rules for turning the cipher's text into plain words: which letters should be swapped, when to turn a phrase on its head, when to ignore a word altogether. Establishing that type of rule set, or "key," is the main goal of machine translators too. Except that the key for translating Russian into English is far more complex. Words have multiple meanings, depending on context. Grammar varies widely from language to language. And there are billions of possible word combinations.

But there are ways to make all of this more manageable. We know the rules and statistics of English: which words go together, which sounds the language employs, and which pairs of letters appear most often. (Q is usually followed by a u, for example, and "quiet" is rarely followed by "bulldozer.") There are only so many translation schemes that will work with these grammatical parameters. That narrows the number of possible keys from billions to merely millions.

The next step is to take a whole lot of educated guesses about what the key might be. Knight uses what’s called an expectation-maximization algorithm to do that. Instead of relying on a predefined dictionary, it runs through every possible English translation of those Russian words, no matter how ridiculous; it’ll interpret as “yes,” “horse,” “to break dance,” and “quiet!” Then, for each one of those possible interpretations, the algorithm invents a key for transforming an entire document into English—what would the text look like if meant “break dancing”?

The algorithm’s first few thousand attempts are always way, way off. But with every pass, it figures out a few words. And those isolated answers inch the algorithm closer and closer to the correct key. Eventually the computer finds the most statistically likely set of translation rules, the one that properly interprets as “yes” and as “quiet.”

The algorithm can also help break codes, Knight told the Uppsala conference—generally, the longer the cipher, the better they perform. So he casually told the audience, “If you’ve got a long coded text to share, let me know.”

Funny, Schaefer said to Knight at a reception afterward. I have just the thing.

Niedersä chsisches Landesarchiv-Staatsarchiv Wolfenbüttel

A copy of the cipher arrived at Knight’s office a few weeks later. Despite his comments at the conference, Knight was hesitant to start the project; alleged ciphers often turned out to be hoaxes. But Schaefer’s note stapled to the coded pages was hard to resist. “Here comes the ‘top-secret’ manuscript!!” she wrote. “It seems more suitable for long dark Swedish winter nights than for sunny California days—but then you’ve got your hardworking and patient machines!”

Unfortunately for Knight, there was a lot of human grunt work to do first. For the next two weeks, he went through the cipher, developing a scheme to transcribe the coded script into easy-to-type, machine-readable text. He found 88 symbols and gave them each a unique code: became “lip,” became “o..,” became “zs.” By early March he had entered the first 16 pages of the cipher into his computer.

Next Knight turned to his expectation-maximization algorithm. He asked the program what the manuscript’s symbols had in common. It generated clusters of letters that behaved alike—appearing in similar contexts. For example, letters with circumflexes ( ) were usually preceded by or . There were at least 10 identifiable character clusters that repeated throughout the document. The only way groups of letters would look and act largely the same was if this was a genuine cipher—one he could break. “This is not a hoax; this is not random. I can solve this one,” he told himself.

A particular cluster caught his eye: the cipher’s unaccented Roman letters used by English, Spanish, and other European languages. Knight did a separate frequency analysis to see which of those letters appeared most often. The results were typical for a Western language. It suggested that this document might be the most basic of ciphers, in which one letter is swapped for another—a kid’s decoder ring, basically. Maybe, Knight thought, the real code was in the Roman alphabet, and all the funny astronomical signs and accented letters were there just to throw the reader off the scent.

Of course, a substitution cipher was only simple if you knew what language it was in. The German Philipp, the Latin copiales, and Hock’s allusion to Albanian all hinted at different tongues.

Knight asked his algorithm to guess the manuscript’s original language. Five times, it compared the entire cryptotext to 80 languages. The results were slow in coming—the algorithm is so computationally intense that each language comparison took five hours. Finally the computer gave the slightest preference for German. Given the spelling of Philipp, that seemed as good an assumption as any. Knight didn’t speak a word of German, but he didn’t need to. As long as he could learn some basic rules about the language—which letters appeared in what frequency—the machine would do the rest.

While his family got ready for spring vacation—a “history tour” of the East Coast—Knight looked for patterns in the cipher. He saw that one common cipher letter, , was often followed by a second symbol, . They appeared together 99 times; a frequently came after: .

Knight reviewed common German letter combinations. He noticed that C is almost always followed by H, and CH is often followed by T. This sequence is used all the time in German words like licht (“light”) and macht (“power”). , Knight guessed, might be cht. It was his first major break.

During his vacation, as his daughters played on their iPads at night in the hotel room, Knight scribbled in his orange notebook, tinkering with possible solutions to the cipher. So far what he had was a simple substitution code. But that left scores of cipher symbols with no German equivalent.

So one evening Knight shifted his approach. He tried assuming that the manuscript used a more complex code—one that used multiple symbols to stand for a single German letter.

Knight put his theory to the test. He assumed, for example, that , , and all stood for I. It worked. He found others, and soon he started assembling small words, like or der (“the” in German), which Knight recognized from World War II movies. Then he got his first big word: , or candidat, followed by , or antwortet (“the candidate answers”). The cipher’s wall of secrecy was crumbling.

But some of the cipher’s symbols—especially iconic ones like , , and —remained baffling. Worse, he couldn’t get German translations for any of the cipher’s standard Roman letters.

On March 26, Knight reviewed his notebook. The words of his first phrase—Der candidat antwortet—were separated by an and an . That made no sense if the coded and stood for German letters. That’s when Knight realized how wrong his initial assumption had been. The unaccented Roman letters didn’t spell out the code. They were the spaces that separated the words of the real message, which was actually written in the glyphs and accented text.

Niedersä Landesarchiv-Staatsarchiv Wolfenbüttel

On March 31, Knight sent an email to Schaefer and her boss, Beáta Megyesi, head of Uppsala's department of linguistics and philology, who was also interested in the manuscript. "I think I've been making some progress," he wrote, and included two lines from the cipher: dieser schlag id das zeiche und der anfang de jenige vertraulichheit die der bruder von jetzo an als geselle von uns zunerwar ...

Schaefer stared at the screen. She had spent a dozen years with the cipher. Knight had broken the whole thing open in just a few weeks.

The message in these two lines was almost as remarkable. Schaefer made a few tweaks and sent back a tentative translation: "This stroke is the sign/the symbol and the beginning of the confidentiality/familiarity that the brother, from now on companion, can expect of us ..."

It was an initiation ritual, Schaefer said. Geselle literally means a "companion." But she knew the term was also used in fraternal orders—clandestine societies like the Freemasons. In this context, a geselle was a rank in a secret society.

Schaefer's boss, Megyesi—a 41-year-old Hungarian-migré—was especially taken by the cipher's contents. "I would not mind being chased by a secret org," she emailed Knight. At night, after she was done managing her department of 450 courses and 25 professors and after she put her twins to bed, Megyesi sat at the computer, turning the symbols into text. She and Knight started emailing multiple times a day about the cipher—and signing their emails in Copiale cipher text.

But they still hadn't cracked the code's big symbols—especially , which they transcribed as "lip." Megyesi and Schaefer were pretty sure it stood for a word, not a letter. But they weren't sure what word it meant.

Then one night in the middle of April, while Megyesi was working late in her office, she stared absentmindedly at the neatly arranged folders on her desk. She looked at a page containing the lip symbol. Schaefer walked into her office just as she was thinking about this. Megyesi looked up. "This symbol," Megyesi said to Schaefer, "it's not a lip. It's an eye."

Niedersä Landesarchiv-Staatsarchiv Wolfenbüttel

As it turned out, Schaefer had made a discovery of her own. A phrase in the Copiale text, a reference to the "light hand" required to be a master of the society, had seemed familiar to her. So she dug up an academic article she had read some time before about a secret order in Germany that called itself the Great Enlightened Society of Oculists. The "light hand" was mentioned in their bylaws.

It was a massive breakthrough. Active in the mid-18th century, the Oculists fixated on both the anatomy and symbolism of the eye. They focused on sight as a metaphor for knowledge. And they performed surgery on the eye. "We exceed all other [healers] by being able to pierce all cataracts, whether they're fully developed or not," the group boasted in its public—and uncoded—bylaws.

Centered in the town of Wolfenbüttel, Germany, the Oculists, it was believed, played the role of gatekeepers to the burgeoning field of ophthalmology. They kept out the "charlatans" who could cause someone to "lose their eyesight forever."

On their crest, the Oculists featured a cataract needle and three cats (which, of course, can see in near darkness). In their bylaws, the Oculists' emphasis on the master's "light hand" seemed to be a reference to members' surgical skill. And they appeared to have a rather progressive attitude; women could be Oculists, just like men.

Schaefer contacted the state archives in Wolfenbüttel, which housed a collection of Oculist materials. The archives had a coded text just like the Copiale—and some cool amulets too.

Megyesi plunged even deeper into the cipher. But the text confused her. The weird rituals it described didn't exactly seem like medical school classes. Although the Copiale mentioned the master's "light hand," Megyesi couldn't find anything in the coded text about eye surgery or cataracts.

Instead the Copiale noted that the master had to "show his skill in reading and writing of our cipher." These Oculists might have been presenting themselves as ophthalmologists in public. But inside the order's chambers, the light hand must have meant something else. Could it have been about keeping secrets through cryptology?

Even with its code broken, the Copiale's swirl of ritual and double-talk was getting harder and harder to follow—especially for someone whose experience with secret orders was drawn mainly from cheesy movies. Megyesi knew she needed help figuring out what these societies were all about. So she asked around for someone who could tell her what really happened in those candlelit initiation rooms.

Courtesy of Uppsala University

Officially, Andreas Önnerfors is a historian of ideas. But he spends a lot of his time as one of 50 or so university researchers in the world seriously examining the historical and cultural impact of secret societies. When Megyesi contacted him, Önnerfors readily agreed to read this newly decoded document from a clandestine order. "Like the kid who sees candies, I could not resist," he says, tugging gently at his ascot. "Plus, my boss wasn't there."

They agreed to meet in September in the castlelike university library in Lund, Önnerfors' cobblestoned hometown in southern Sweden. Megyesi and Schaefer came down from Uppsala with the Copiale manuscript. Knight flew in from California.

Hundreds of thousands of Europeans belonged to secret societies in the 18th century, Önnerfors explained to Megyesi; in Sweden alone, there were more than a hundred orders. Though they were clandestine, they were often remarkably inclusive. Many welcomed noblemen and merchants alike—a rare egalitarian practice in an era of strict social hierarchies. That made the orders dangerous to the state. They also frequently didn't care about their adherents' Christian denomination, making these orders—especially the biggest of them, Freemasonry—an implicit threat to the authority of the Catholic Church. In 1738 Pope Clement XII forbade all Catholics from joining a Masonic lodge. Others implied that the male-only groups might be hotbeds of sodomy. Not long after, rumors started that members of these orders actually worshipped the devil.

These societies were the incubators of democracy, modern science, and ecumenical religion. They elected their own leaders and drew up constitutions to govern their operations. It wasn't an accident that Voltaire, George Washington, and Ben Franklin were all active members. And just like today's networked radicals, much of their power was wrapped up in their ability to stay anonymous and keep their communications secret.

After reading the Oculists' cipher, Önnerfors suggested that it described one of the more extreme groups. Forget the implicit threats to the state or church. In part of the Copiale, there's explicit talk about slaying the tyrannical "three-headed monster" who "deprive[s] man of his natural freedom." There's even a call for a "general revolt." Remember, Önnerfors told the code-breakers, this book was written in the 1740s—30 years before the Declaration of Independence. "To someone at the time," he added, "this would be like reading a manifesto from a terrorist organization."

To Önnerfors, decoding the Copiale was a significant achievement. Traditionally, historians have just ignored documents like this, because they don't have the tools to make sense of them. That's why the Oculists passed as early surgeons for so long. But there are scores of these enciphered documents—many in Lund alone. Some concern new rites of a fraternal order; others could detail political movements. There's no way to tell for sure, because they're cryptologically sealed. There's a whole secret history of the West waiting to be told. There are so many more codes.

Decoding the Copiale ——————–

Cracking the so-called Copiale cipher was a three-step process. First the characters had to be rendered as machine-readable text: became "eh," and became "lip." Next, software analyzed the behavior of the cipher letters and guessed that the Copiale's original language was German. The code-breaking team then was able to translate the text into German and finally into English, revealing a secret manual of an esoteric society. Here's how it worked.

Sample of original text

Machine-readable text z ns eh n hd iot hk tri j ns ah b mal tri nu h z ih plus c ni three bar d r. ki mu del oh s z uh three zs lip o.. pi iot oh r g zzz ni x. ns ah j iot del gam zzz y.. lam l iot hk p z eh plus f plus uu cross c. iot bas uu c del grr cross c. oh arr lam f h. nu x. uh : j sqp lam e m. ns r. gs m. c. : uu h tri sqi : lam gs grr y.. ru ah ds bar p. arr uh b m. oh c. : uu h tri sqi c. tri bar n z grr bar m. ah x. uu o m. grr iot c. n bar ns uh c x. ih hd zzz y.. plus zs del eh hd n. c. lam uu

German results die historie von dem ursprunge der *lip* *o..* die neugierigkeit ist dem meNschlicheN geschlecht an geerbt wir wolleN offt eine sache wisseN blos des wegeN weil sie geheim gehalteN

English translation The history of the origin of the Oculist society. Curiosity is the inheritance of mankind. Frequently we want to know something only because it needs to be kept secret.

These unaccented Roman letters appeared with the frequency you'd expect in a European language. But they don't represent letters—they mark the spaces between words.Algorithmic analysis showed that letters that looked alike also acted alike. These all actually stand for the letter E. It's a way to confuse codebreakers.The Copiale's more unusual symbols denote words, not letters—in this case, "Oculist" and "society."On October 25, 2011, The New York Times published a story about the Copiale, focusing on Knight's code-cracking techniques. A flood of media attention followed—along with hundreds of emails from people who claimed to have ancient ciphers of their own. In December, when I visited Knight, he had just received a picture from Yemen. Some Bedouins had found a stone with an unknown, squarish script. Perhaps Knight could tell them what it said?

This was unfamiliar turf. Knight and the other members of the Copiale team weren't used to such attention. And not all of it was positive: There were also miffed Masons telling him he didn't understand the full picture, and warnings from the fringe set telling them to stop spilling dusty secrets or claiming that Lucifer was really the Freemason god.

Back in Lund, Önnerfors grew surprised too as he continued to plumb the Copiale. In the midst of the descriptions about Oculist rituals, the document took a narrative turn. It described a meeting of "a few good friends" who talked about people's desire to "know something only because it needs to be kept secret." The friends decided to use this curiosity to play a little prank. They set up a fraternity and "would agree immediately as they would like to pretend that a great secret would be behind their unification." They called this farce, this hoax, this grand psychological experiment Freemasonry. In other words, the Oculists were making an outrageous claim: that they founded Freemasonry ... as a joke.

That certainly wasn't true, but at the very least the Oculists seemed to be watching Freemasonry's every move. Starting on page 27 and continuing for the remaining 78 pages, the cipher detailed the rituals performed by the highest degrees of the Masonic order—rites unknown to ordinary Masons at the time. Nothing was omitted from the Copiale's descriptions of these top-level rituals. Not the skulls. Not the coffins. Not removal of undergarments nor the nooses nor the veneration of Hiram Abiff, builder of the Great Temple of Jerusalem, whose decomposed body became the alchemical emblem for turning something rotten into something miraculous and golden.

Decades later, most of these practices became widely known as the Freemasons' secrets seeped out. But in the 1740s they were still well concealed—except to the Oculists. The Oculists were a secret society that had burrowed deep into another secret society. Önnerfors noted that the cats on the Oculists' insignia were watching over mice. It could be another Oculist joke — or a sign that they were spies.

Niedersä Landesarchiv-Staatsarchiv Wolfenbüttel

Before their cipher was broken, the Oculists were practically unknown. The main thing historians in Wolfenbüttel knew about the group was that it was led by a count named Friedrich August von Veltheim, who died in April 1775. Like many aristocrats of his day, he belonged to multiple secret societies, including an Order of the Golden Poodles, which likely sounded as goofy back then as it does today. But in his will, his Oculist heirlooms merited special instructions. He had locked all of the Oculists' objects in a leather trunk and ordered his son to make sure the seals remained unbroken until the local duke (or one of the duke's descendants) said otherwise. If the count's goal was to make sure that whatever was inside that trunk faded into obscurity, he succeeded. The trunk wasn't opened until 1918. Its contents—now at the state archives in Wolfenbüttel—have rarely been examined since.

After months of talking about the Oculists with Knight, Schaefer, Megyesi, and Önnerfors, I decided this past winter to see Count von Veltheim's trove for myself.

Unable to make the trip personally,Önnerfors arranged for his mentor—a professor named Jan Snoek—to meet me at the archives. Snoek is a high-degree Mason who has designed his own rituals for the order. We met at the archives in Wolfenbüttel and found a series of rectangular boxes waiting for us.

Snoek and I took them into a private reading room with circular windows that overlooked a browning forest. Inside the first box was the silver-dollar-sized seal of the Oculists; its watchful cats and pince-nez perfectly preserved thanks to almost two and a half centuries of near isolation. Another box revealed a bone-handled cataract needle and the luminescent green aprons that members wore. Inside a third box were five oval amulets bearing raised blue eyes so anatomically correct I half expected them to wink.

There was also a tiny cylinder, covered in jade and gold—the colors of the Copiale itself. I screwed it open to find a tortoise-shell cup holding an eye made of ivory and horn. The model came apart like a Russian doll: pupil inside lens, iris on top of pupil, cornea resting on iris. Each layer was more exquisite than the next.

Niedersä Landesarchiv-Staatsarchiv Wolfenbüttel

The artifacts laid out in the reading room also undercut the idea that the Oculists were sleeper agents on a mission to expose Freemasonry. Why would spies need all these extra rituals? Or be so interested in anatomy?

Put yourself in a Mason's shoes, Snoek explained. The Catholic Church has outlawed your order—and every other secret society. You don't want to give up your Freemasonry, but you don't want to be accused of sodomy. Even in a largely Protestant country like Germany, that was a withering accusation at the time. So "you hide it in a veil," Snoek said. You start a new set of rituals, to layer on top of the old—and make it impregnable to Vatican attacks.

Perhaps the Oculists weren't spying on Freemasonry so much as keeping it alive.

"As a Mason you are not allowed to write down—let alone publish—your rituals," Snoek said. So how do you spread your ideas? You publish esoteric rites as if they are exposures—public outings of Masonry. Except you publish in code, so only an elite cadre of fellow Masons can read the dangerous things you have to say. And when your mission is over, you stuff all the evidence into a box that doesn't get opened for nearly 150 years. The Oculists guarded and transmitted the Masons' deepest secrets, Snoek believes, using a mixture of ritual, misdirection, and cryptography.

Eventually we turned to the last items in the Oculist trove: nine copies of a four-page document written in a mixture of old German, Latin, and the Copiale's coded script. The message was more or less identical in every set. "Die Algebra," it said at the top of page one, a primer on the "old way of calculating." Rows of cipher letters lay beneath. The document seemed to add them up as if they were numbers. The third page mentioned the Jewish Cabala—the mystical system in which meaning is derived from the numerical value of letters.

It would appear that the Copiale symbols don't represent just words and letters, they stand for numbers too. But if they do, Knight, Megyesi, and Schaefer haven't been able to tease out the meaning. The Oculist master apparently understood these coded documents in a way that today's interpreters do not. Despite years' worth of attacks on their cipher, the Oculists' secrets have not been pried loose, at least not fully. What they saw in their initiation chambers may never again be seen.

Contributing editor Noah Shachtman (noah.shachtman@gmail.com) wrote about Russian cybersecurity mogul Eugene Kaspersky in issue 20.08.