In one of Warren G. Harding’s torrid love letters to his mistress Carrie Fulton Phillips, sent during the 1910s and ’20s, the future US president enclosed a long list of code words that the couple could use to communicate secretly. “Cloudy” meant “message not clear.” “Repair” meant “arrive in New York on [Date].” “Grateful” stood for “all my love to the last precious drop.”
Like Harding and Phillips, lovers throughout history have needed to conceal their messages from spouses, parents, even from the authorities, and have come up with a variety of creative ways to do so: codes, ciphers, word games, or playful acronyms and abbreviations. There's a broad spectrum between codes to which only two people know the key, like "grateful," and ones that are more widely understood, like modern-day texting shorthands "ILY" or "143." Some codes are created from deadly necessity, others to show off one's cleverness in wordplay. Either way, there's something about the creation of a secret, shared language—one writing in code, the other holding the key to decipher it—that gets at the very heart of what it means to write your lover in the first place.
While Marie Antoinette was imprisoned in the Tuileries during the French Revolution, she sent a number of letters to the Swedish Count Axel von Fersen, who had assisted in her failed escape attempt. Some were written in invisible ink; others were written in an alphabetic-substitution cipher relying on an encryption table that Fersen and the queen probably each had a copy of. According to recent research by French cryptographers, the queen wrote to Fersen not just to plead for his aid, but also to reassure him of her enduring love. "I cannot write any more but nothing in the world could stop me to adore you up to the death," she wrote in code, as the researchers translate it.
Other famous love-letter writers have faced less fatal threats, but still found reasons to encrypt their words. Prolific 19th-century English diarist Anne Lister created a Greek-influenced code that she used to keep her letters to female lovers private. A historian recently discovered that Edward Everett Hale, the prominent (and married) Boston-born 19th-century Unitarian minister and writer, was sending secret love notes in an arcane shorthand, Towndrow script, to a much younger woman named Harriet Freeman. Sometimes codes designed for romantic purposes have ended up useful in quite different situations: A British prisoner of war in Nazi Germany, Captain Pat Reid, used the linguistic codes he'd designed to write letters to his various girlfriends back home to baffle the Germans in letters about troop movements. Other codes have provided romantic continuity across a lifetime. The Globe ran a story last summer about a couple, separated for 60 years, who reunited when one wrote the other a love note using the alphabet-based cipher she had taught him as a teenager.
In the 18th and 19th centuries, one playful way to show your affection on Valentine's Day was to compose an acrostic poem, the first letter of each line spelling out your beloved's name. Newspapers ran examples, and poets like Edgar Allen Poe wrote them (and received them: Poe's wife Virginia wrote him an acrostic Valentine the year before she died). These were generally public displays of linguistic dazzle, not private codes only shared between two people, but there could still be an aspect of mystery. A short story published in the Feb. 16, 1889, Lincoln, Neb., Capital City Courier tells the tale of a girl whose mother disapproves of her boyfriend and cuts off all communication. He manages to slip her a Valentine poem by telegram, its acrostic spelling out a secret message directing her to the post office. There she finds his real letter—asking her to marry him.
Soldiers during the World Wars had to contend with both loneliness at the front and censors reading all of their mail. In the abbreviation-happy early 20th-century, this meant the creation of a number of clever and/or salacious acronyms, which could be written on the envelope of an anodyne letter home, perhaps next to an upside-down stamp indicating love. CYK (consider yourself kissed) and SWAK (sealed with a kiss) existed as early as 1915 and are collected in a contemporary study by Percy W. Long. Other wartime favorites included, according to slang lexicographer Jonathon Green, HOLLAND (“hope our love lasts and never dies”); BOLTOP, often written over an “x” (“better on lips than on paper”); BURMA (“be undressed, ready, my angel”), and several others that are rather less SFW. Of course, Green said, some of these codes grew famous enough to defeat the purpose: “Every censorship officer who looked at these would say, ugh, another [BURMA].”
Today's texting and instant messaging codes are similarly public. Although abbreviations like "143" (from pager days, for the number of letters in each word of "I love you") or parental-censor-evaders like "MOS" ("mom over shoulder") were invented to shield private messages, most of them have long been cracked, or can be with a simple online search. Now, though, there are apps that can quickly do the work of Marie Antoinette and her Swedish courtier's elaborate encryption tables. The Cipher Sender app puts text messages into a variety of different ciphers, and then unencrypts them at the other end. And Send.Morse allows you to do the same in Morse code—perfect for texting an old-timey acrostic Valentine to your modern-day sweetheart.
Britt Peterson is an Ideas columnist. She lives in Washington, D.C. Follow her on Twitter @brittkpeterson.