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The letter X: Marks the spot

Photo:  Wolfgang Rattay (Reuters)
Photo: Wolfgang Rattay (Reuters)

The alphabet’s wayward child

The letter “X,” the 24th letter of the English alphabet, is something of a rebel.

Read more

A marker of the mysterious, the explicit, and the extraordinary, both a letter and a numeral—“X” is simply an unparalleled symbol (no pun intended).

On a test, it is a wrong answer, but at the bottom of a letter, it denotes affection. It means a strike in a bowling alley, a cancellation on a flight board, or an unsolved quantity in an equation.

In English, it is pronounced like a “Z” (“xylophone”) or “KS” (“fox”) or “GZ” (“exit”), or in borrowed forms, it sometimes becomes silent altogether (“faux pas”). With all this variation, it’s no wonder that the mutable letter is popular for branding, naming, and the labeling of discoveries.

Let’s see what else we can dig up—“X,” after all, marks the spot.

Origin story

How the letter “X” came to be

Some linguists theorize it comes from the Phoenician letter samekh, pronounced with a hard “s,” the meaning of which (pdf) may have been something akin to “pillar,” “peg,” “support,” or quite literally “fish,” given its resemblance to a fish skeleton.

According to one theory, the Greeks borrowed samekh, which became chi (X) in the Ionic alphabet and was pronounced with a hard “K” sound. The Etruscans, and later the Romans, adopted the Ionic letter, but paired it with the “X” sound (pronounced “ks”) used by the Chalcidians of western Greece, forming the letter “X” in the Latin language.

The evolution of “X” likely took place over thousands of years, with the Phoenician writing system emerging around 1050 BCE, the Roman alphabet around 800 BCE, and the Latinate letters we are familiar with today around the 7th century CE.

Fun fact!

Long before “XXX” became a mark of explicit material, it was a symbol found on another taboo commodity: moonshine. During Prohibition, the triple “X” label indicated the bootleg was triple distilled, and therefore had a higher, purer alcohol content. This explains why you tend to see it on bottle labels in old cartoons.

Explain it like I’m 5!

X, the unsolved symbol

“X” may have started as a letter, but it eventually it found its way into mathematics. There are two leading theories as to how that came to be.

The first theory dates back about 1,200 years ago, to a mathematical treatise by Persian polymath and so-called father of algebra, al-Khwārizmī. In his work, the Arabic word for “thing,” shay’, is used to refer to unknown quantities. That in turn was translated into medieval Spanish and written as xei, which may have eventually been abbreviated to just “X.”

A competing theory is that the use of “X” in math originated with French philosopher René Descartes in his treatise La Géométrie (1637), which used lowercase letters at the end of the alphabet—x, y, and z—to signify unknown quantities. While Descartes may not have come up with the idea first (he has a record of poaching ideas from others), it could be that he popularized the convention.

Portrait of interest

Image:  John Singer Sargent
Image: John Singer Sargent

Madame X

The painting Portrait of Madame X (1883-1884) by American artist John Singer Sargent caused quite the stir among the Parisian beau monde when it was exhibited in the famous Salon of the Academie des Beaux-Arts in 1884.

The sensual and mysterious depiction of its subject, socialite Virginie Amélie Avegno Gautreau, was met with mixed reviews. The original painting showed a sparkling strap on her dress slipping suggestively down one shoulder, and the overall vision was so bold for its time, and caused such a controversy, that Sargent was compelled to move to London permanently.

Originally the painting was named Portrait de Mme ***, but Sargent later changed it to Madame X, lending that extra je ne sais quoi. In 1916, when Sargent sold the painting to the Metropolitan Museum of Art in New York City, he reportedly said: “I suppose it is the best thing I have done.”

Pop quiz

Which “X”-named individual said: “You know I believe true balance lies somewhere between rage and serenity.”

A. Malcolm X

B. Xenophon

C. Pope Pius X

D. Professor X

The x-act answer can be found at the bottom.

Watch this!

The hunt for treasure

The famous line “X marks the spot” was once delivered by none other than Harrison Ford in the film Indiana Jones And The Last Crusade (1989). Here’s a clip of that scene, and while you’re at it, check out John Williams’s original song of the same name, composed for the film.


Elon Musk’s X obsession

“X” is a popular letter to use for branding—just look at Xerox, Xbox, Roblox, Clorox, Xfinity, Gas-X, to name a few. But there is no greater devotee to the letter, perhaps, than Elon Musk.

X.com: The domain was claimed in 1999 by Musk and three business partners who were founders of an online bank. Following a merger with Confinity in 2000, Peter Thiel took over the company and it was renamed PayPal. Musk bought back the domain from PayPal in 2017. The site still remains blank.

SpaceX: Musk’s ambitions to enter the space industry took off in 2002 with the founding of the private spacecraft and satellite company.

Model X: The name given to one of Musk’s Tesla models that began production in 2015.

X Corp: The Twitter owner recently renamed the social media platform X Corp in alignment with his ambition of creating an “everything app.”

X: That superapp, which takes a page from China’s WeChat, has been dubbed “X”—though much else about the project remains a mystery. Musk has said his Twitter purchase was all part of a grander plan.

X Æ A-12: A different category entirely, this string of letters and numbers is in fact the name of one of Musk’s children with Canadian singer Grimes. The child’s first name is “X,” and full name is pronounced “X Ash A Twelve.” Their second child was named “Exa Dark Sideræl Musk,” but that name has reportedly been changed by Grimes to simply the letter “Y.” Musk’s eldest child, Saxon, also received an “X” in his name.


Which is the superior “X” logo?

Make your X on the line by answering our poll (it’ll just take a few seconds).

💬Let’s talk!

In last week’s poll about happiness, you were basically evenly split between being happy as a clam, happy as a room without a roof, and happy as a 50-year-old making $127,000 per year (statistically, the ideal scenario).

🐤 Tweet this!

🤔 What did you think of today’s email?

💡 What should we obsess over next?

Today’s email was written by Julia Malleck (a relates-heavily-with-Mulder X-Files fan), edited and produced by Annaliese Griffin (lacks a middle name and occasionally uses “X” as a middle initial on forms), and, of course, brought to you by the letter X.

The correct answer is D., Professor X, a.k.a. Charles Xavier from X-Men.

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