The Poison-Detecting Secret Weapon of the Middle Ages: Unicorn Horn

A woodcut of a unicorn from 1551
A woodcut of a unicorn from 1551

In the Middle Ages and into the Renaissance, Europeans knew that unicorns were real. After all, their horns were the treasured possessions of royalty, nobility, and even clergy. Charles VI of France had one, as did Lorenzo de Medici, and Danish rulers sat on a throne carved out of them. Queen Elizabeth I had a fully intact horn she used as a scepter; it was valued at 10,000 pounds—roughly the cost of a castle in her day. In fact, unicorn horns were considered so valuable the Elizabethan dramatist John Dekker wrote that one was "worth a city."

But unicorns horns weren't prized just for their beauty or rarity, or as tokens of extreme wealth. They were believed to be powerful defense against disease—and poison.

Fierce But Pure

Oil painting of a woman and unicorn by a follower of Timoteo Viti
Chastity, oil painting by a follower of Timoteo Viti

For an animal that never existed, the unicorn got around. The ancient myths of India and China mention unicorn-like animals, as did the tales Greek travelers brought back from India and other far-flung lands. The earliest Greek description is from the historian Ctesias, who wrote around 400 BCE of a large, agile animal with a white body, dark red head, and a long horn on its forehead. About a hundred years later, scholars translating the Old Testament interpreted a horned animal known in Hebrew as re'em as a unicorn (though modern translators prefer the term auroch, an extinct species of cattle). Writing in the first century CE, Pliny the Elder described the unicorn is "the fiercest animal, and it is said that it is impossible to capture one alive. It has the body of a horse, the head of a stag, the feet of an elephant, the tail of a boar, and a single black horn three feet long in the middle of its forehead.”

From the beginning, accounts of the unicorn emphasized their healing and purifying properties. Ctesias wrote, "Those who drink out of these horns, made into drinking vessels, are not subject, they say, to convulsions or to the holy disease [epilepsy]. Indeed, they are immune even to poisons if, either before or after swallowing such, they drink wine, water, or anything else from these beakers." Similar accounts appeared for centuries: Around the 3rd century CE, the Greek intellectual Philostratus wrote that "the Indians make drinking-cups from this horn, which have such virtue that the man who drinks from one will for one whole day neither fall ill, nor feel pain if wounded, nor be burned by passing through fire, nor even be affected by poisons which he could not swallow at any other time without harm."

By the 12th century, a German nun known for her saintly visions, Hildegard of Bingen, recommended a paste of powdered unicorn liver and egg yolk as a cure for leprosy, although she conveniently noted that it could fail if the "leper in question happens to be one whom death is determined to have or else one whom God does not wish to be cured." Unicorn hide was also recommended in boots and belts, partly as prevention for that greatest scourge of the Middle Ages: plague.

Belief in the healing powers of the unicorn focused especially on its mysterious, twisting horn. The substance, often called alicorn, was associated with great purity as well as healing, sometimes with religious overtones (the purity of the white animal was thought to be connected to Jesus Christ, and the horn to his cross). Hunters in search of a unicorn were supposed to lure the animal with a female virgin, capturing the animal once it fell asleep in her lap.

A Common Deception

Narwhal tusk
A narwhal tusk

Of course, no such hunters were ever successful. Objects portrayed as being made from unicorn sometimes came from rhinoceroses or mammoth fossils but most often in Europe from narwhals, which were hunted by the Vikings in the North Atlantic. The Vikings harvested the narwhals’ spiraling tusks and sold them on to traders who either didn't know, or didn't care, about their true origins in the sea.

Once obtained, alicorn could be taken in many forms. Powdered, it was applied to dog bites and other wounds or consumed as treatment for plague, gout, and other diseases. The influential German physician Johann Schröder recommended it for childhood epilepsy. And although other physicians numbered among the earliest skeptics, apothecaries used unicorns widely in their potions. Eau de licorn—water purified by the introduction of unicorn’s horn or by being poured through a hollowed-out segment of horn—was also widely sold and reputed to have health benefits.

While the extraordinary cost of the intact horns made them showpieces for the rich, powdered unicorn horn was an affordable remedy for the average citizen. This was largely because other substances could be easily substituted: horse hoofs, fossils, and other types of horn. In fact, the widespread problem of fraud led to frequent tests of the authenticity of the horn itself, including presenting it to spiders and scorpions and observing to see if they avoided it or died. If they did, the item was thought to be genuine horn.

Poison-Proof

A page from a 17th-century French medical text discussing unicorns
A page from a 17th-century French medical text discussing unicorns

Poisoning was particularly feared during the Middle Ages and into the Renaissance by the back-stabbing royalty and nobility keen to maintain their positions, not to mention their lives. Such an insidious crime required extraordinary measures: While European royalty kept other poison-detectors, including rubies, bezoar stones, and griffin claws, unicorn horn was a favored material for protection as well.

Whole unicorn horns were deployed on dining tables as poison detectors, while fragments of horn, called touches by the French, could be touched or dipped to plates of food to detect the presence of toxins. They could also be hung on chains or mounts of precious metal (actually less valuable materials, pound for pound, than the horn itself). French royalty had utensils made with alicorn, while other members of the European nobility had the horn inset into jewelry. The horn was expected to provide an alert to the presence of poison by changing color, sweating beads of moisture, or actually steaming. Alicorn might also be dipped into water or run over the actual linens and wall hangings in a banquet hall. Goblets fashioned from unicorn horn were also made across the continent; some believed these would shatter upon contact with a contaminated beverage.

While some medical writers, such as the famed French surgeon Ambroise Paré, were skeptical of the powers of the unicorn horn, many others believed in its merits. The Italian scholar and naturalist Andrea Bacci wrote a defense of the horn's use in 1573, telling the story of a man who consumed a poisoned cherry but was saved thanks to unicorn horn dissolved in wine. He also described an experiment in which two pigeons were fed arsenic, but the one who was given some scrapings of unicorn horn recovered and lived. The other died two hours after being fed the toxin [PDF].

But by the 17th century, the myth of the unicorn had begun to tarnish. European travelers to the Arctic brought back tales of the living narwhal, and further missions to other continents disproved the existence of unicorns by process of elimination, since no such animal was ever sighted. In July 1661, the men of the newly formed Royal Society put unicorn horn to the test: They placed a spider in a circle of powdered unicorn’s horn to see what would happen. From from being repelled by the horn, as writers had long claimed, the spider immediately scurried across the powder to escape. The men repeated the experiment several times, each with the same results. Their trial helped sound the death knell for credulous belief in the magical properties of unicorn horn.

The loss of value resulted in the disappearance or destruction of many precious specimens. Items once said to be made from unicorn horn are still in some museum collections, and very occasionally turn up for sale—still bearing their historical value, though no longer imbued with the mysterious properties that once made them worth a city or a castle.

11 Facts About John James Audubon

John James Audubon Center at Mill Grove and the Montgomery County Audubon Collection, Audubon.org // Public Domain
John James Audubon Center at Mill Grove and the Montgomery County Audubon Collection, Audubon.org // Public Domain

You might be familiar with the name John James Audubon from the bird conservation-focused Audubon Society—which he had nothing to do with founding—or the famous illustrations in his groundbreaking natural history collection, The Birds of America. But there are a few surprising bits of history about this quintessential American naturalist ... like the fact that, originally, he was neither American nor named Audubon.

1. John James Audubon immigrated to America to avoid serving in Napoleon Bonaparte’s army.

John James Audubon was born Jean Rabin in April 1785 in the French colony of Saint-Domingue (now Haiti). He was an illegitimate son of a French naval officer/plantation owner, Jean Audubon, and a chambermaid named Jeanne Rabin, who died soon after he was born. In 1791, after Jean Audubon had returned to live in France, he arranged for his son and another illegitimate child to be sent there so he could formally adopt them. Jean Rabin was renamed Jean-Jacques Fougère Audubon.

In 1803, his father sent 18-year-old Jean-Jacques Audubon to Pennsylvania to avoid his conscription into Napoleon’s armies. There, he anglicized his name to John James Audubon.

2. America’s leading ornithologist had a beef with John James Audubon.

Eastern screech-owls from John James Audubon's Birds of America
John James Audubon Center at Mill Grove and the Montgomery County Audubon Collection, Audubon.org // Public Domain

In 1810, before he became a full-time artist, Audubon and his business partner Ferdinand Rozier owned a shop in Louisville, Kentucky. One day, in strolled Alexander Wilson, an eminent ornithologist who was seeking subscriptions for his magnum opus in progress, American Ornithology. (At the time it was common for authors to seek subscriptions from members of the public that would pay for the completion of the work.) As Audubon looked at the engravings, Rozier said in French, “My dear Audubon, what induces you to subscribe to this work? Your drawings are certainly far better.” Audubon ended up taking Wilson on a few hunting trips, but did not subscribe. Wilson would later write about Louisville, “Science or literature has not one friend in this place.”

While Wilson died in 1813—leaving his book unfinished—Audubon was just getting started traveling the country and illustrating birds. When he arrived in Philadelphia, the country’s intellectual capital, he got a chilly reception from Wilson’s colleagues. “[Naturalist] George Ord was so afraid that Audubon would totally bury the great, respected Alexander Wilson,” Roberta Olson, curator of drawings at the New-York Historical Society, told Mental Floss in 2017, that he “arranged for Philadelphia to basically close down [to Audubon], so he could not publish there.” The snub forced Audubon to seek his own subscribers in the UK when he decided to publish The Birds of America.

3. Another Bonaparte tried to help John James Audubon’s artistic career.

In 1824, Audubon met Napoleon’s nephew Charles Lucien Bonaparte, a respected ornithologist. Bonaparte was, ironically, working to complete Wilson’s American Ornithology and was interested in Audubon’s art. Bonaparte even bought his drawing of a great crow-blackbird (now called the boat-tailed grackle) for use in his book. But according to legend, when Bonaparte took Audubon’s drawing to be engraved, the engraver sniffed, “I think your work extraordinary for one self-taught, but we in Philadelphia are used to seeing very correct drawing.” The engraving was made nonetheless, and Bonaparte proclaimed it “a faithful representation of both sexes … drawn by that zealous observer of nature and skilful artist Mr. John J. Audubon.”

4. At first, nobody thought The Birds of America would succeed.

Green herons from John James Audubon's Birds of America
John James Audubon Center at Mill Grove and the Montgomery County Audubon Collection, Audubon.org // Public Domain

After Audubon’s lack of success in Philadelphia, he traveled to Europe to attempt to find subscribers and printers for the hundreds of bird paintings that would become the Birds of America in book form. Audubon had the idea to print his artwork life-size on double elephant paper, measuring around 39.5 inches by 26.5 inches. Initially, the reaction to Audubon’s plan was muted. A bookseller named Mr. Bohn explained that such a giant book would never sell, since it would take up so much space on a table that it would either shame all the other books or render the table useless.

But that was before he saw the drawings. Several days later Audubon met the bookseller again and showed him his work. “Mr. Bohn was at first simply surprised, then became enthusiastic, and finally said they must be published the full size of life,” Audubon wrote. The resulting book, featuring 435 engraved and hand-colored plates, is now one of the most expensive in the world. Rare copies sell at auction for around $10 million.

5. John James Audubon sparked a controversy about vultures …

Before Audubon, vultures had been lauded for their sense of smell. The 1579 text Euphues asks, “Doth not the eagle see clearer, the vulture smell better, the mole hear lightlier?” In the 1770s, Irish novelist Oliver Goldsmith called vultures “cruel, unclean, and indolent” but admitted that “their sense of smelling, however, is amazingly great.”

But in 1826, Audubon presented an “Account of the Habits of the Turkey Buzzard … with the view of exploding the opinion generally entertained of its extraordinary power of Smelling” at the Wernerian Natural History Society in Edinburgh. Audubon described how he could sneak up very close behind a vulture and it wouldn’t fly away until he showed himself. He then ran experiments. In the first, he filled a deer skin with grass to approximate a recently deceased animal and observed a vulture attack the odorless prey. In the second, he hid a putrefying hog carcass in some grass, and no vulture found it, even though the stench prevented Audubon from getting within 30 yards of it.

Most of the Edinburgh crowd agreed with Audubon, but eccentric explorer and naturalist Charles Waterton demurred. Waterton had written of his own experiments in which turkey vultures would take away lizards and frogs “as soon as they began to stink.” But, according to zoologist Lucy Cooke, Waterton “was said to have a habit of hiding under the table at dinner parties to bite his guests’ legs like a dog, and delighted in elaborate, taxidermy-based practical jokes. A particularly inspired prank involved his fashioning an effigy of one of his (many) enemies out of a howler monkey’s buttocks.” So there’s that.

6. … and even Charles Darwin got involved.

Baltimore orioles from John James Audubon's Birds of America
John James Audubon Center at Mill Grove and the Montgomery County Audubon Collection, Audubon.org // Public Domain

Scientists took sides in what the London Quarterly Review called “the vulture controversy.” Nosarians believed vultures used their sense of smell, and anti-nosarians believed they used sight. In South Carolina, some of Audubon’s supporters commissioned a painting of a dead sheep and placed offal 10 feet away from it outdoors. Vultures attacked the painting. Even Charles Darwin conducted experiments on whether vultures could smell.

Later research [PDF] suggested that Audubon likely mistook black vultures (Coragyps atratus), which primarily use sight, for turkey vultures (Cathartes aura), which actually use smell to locate carrion. Cooke notes that Audubon described animals that seem to occasionally hunt live animals, which indicates black vultures, not turkey vultures. Most New World vultures use sight, and only a few use smell. Back in the 19th century, Waterton had been increasingly shunned for his anti-nosarian views. “Which is a shame” Cooke writes, “because he was right.”

7. John James Audubon discovered birds that don’t exist.

Audubon is credited with discovering around 25 species and 12 subspecies, but some of his other birds were later identified as being either immature birds or sexually dimorphic specimens. Beyond these, there are five “mystery birds” that appear nowhere but in Audubon’s watercolors: the carbonated swamp warbler, Cuvier’s kinglet, Townsend’s finch (or Townsend’s bunting), small-headed flycatcher, and blue mountain warbler. The Audubon Society also includes the Bartram's vireo in the list. These unidentifiable birds were probably hybrids or known birds with aberrant colorations.

8. John James Audubon might have been the first bird bander.

Great egret from John James Audubon's Birds of America
John James Audubon Center at Mill Grove and the Montgomery County Audubon Collection, Audubon.org // Public Domain

Soon after arriving in the U.S., Audubon attached tied some silver thread around the legs of Eastern phoebes (he called them pewee flycatchers). The birds left the area in October. When they returned the following spring, Audubon found two still sporting silver threads. His experiment is often called the first bird banding experiment in the western hemisphere.

A recent article in Archives of Natural History casts doubt on the story, though. Audubon claimed 40 percent of his tagged eastern phoebes returned home, but a larger scale study found only around 1.5 percent of banded birds returned. Audubon may have been in France at the time of the phoebes’ return, too.

9. John James Audubon illustrated a long-lost New Jersey bank note.

Generations of Audubon scholars have hunted for a mysterious bank note that Audubon allegedly illustrated in 1824. In his journals, Audubon wrote, “I drew … a small grouse to be put on a bank-note belonging to the state of New Jersey.” It’s believed that this was his first engraved bird illustration, but no one was able to find any evidence of its existence—until 2010, when historians Robert M. Peck and Eric P. Newman found the sample sheets the engraver had produced with stock images for the currency. Among the George Washingtons and bald eagles was a little heath hen. Peck told NPR, "A little scurrying grouse rushing into a bed of grass is not the kind of confident image that a bank president wants to convey,” so a bald eagle probably replaced it on the currency.

Similarly, heath hens went extinct in 1932, but some researchers have proposed bringing them back.

10. John James Audubon had nothing to do with the Audubon Society.

Jays from John James Audubon's Birds of America
John James Audubon Center at Mill Grove and the Montgomery County Audubon Collection, Audubon.org // Public Domain

After Audubon published The Birds of America and established himself as America’s premier naturalist, he bought land and a mansion in rural upper Manhattan in New York City. Audubon died there in 1851, but his wife, Lucy, continued to live in the estate later known as Audubon Park. In 1857, businessman George Blake Grinnell and his family moved to Audubon Park, and Lucy became a teacher for his son, 7-year-old George Bird Grinnell. Grinnell later became a respected naturalist, editor-in-chief of outdoors magazine Forest and Stream, and an advocate for conservation.

In 1886, he founded the Audubon Society and the next year The Audubon Magazine, inspired by his childhood classes with Lucy, whom he remembered as a “beautiful, white-haired old lady with extraordinary poise and dignity; most kindly and patient and affectionate, but a strict disciplinarian of whom all the children stood in awe.” He also cofounded the conservation-minded Boone and Crockett Club with Theodore Roosevelt. But by 1889, the pressures of running multiple journals and societies proved too much, and the Audubon Society folded.

11. Two women, inspired by fashionable hats, revived the Audubon Society.

In 1896, Boston socialites Harriet Lawrence Hemenway and her cousin Minna B. Hall were horrified after reading an account of the plume-hunting industry—a trade that killed millions of wild birds to supply feathers for millinery. They resolved to stop their fellow fashionistas from wearing wild feathers. The two founded the Massachusetts Audubon Society and sent a letter to Forest and Stream to ask people to take a pledge “not to purchase or encourage the use of feathers of wild birds for ornamentation.” More regional Audubon Societies sprang up around the country, and in 1940 they combined to form the National Audubon Society. Today the organization focuses on science-based conservation and education to protect birds, continuing John James Audubon’s legacy into the 21st century.

The Mystery of the Missing Keepers at the Flannan Isles Lighthouse

iStock.com/Westbury
iStock.com/Westbury

In December 1900, a boat called Hesperus set sail for the island of Eilean Mor, one of the seven islets (also known as the “Seven Hunters”) of the Flannan Isles off the coast of northwestern Scotland. Captain James Harvey was tasked with delivering a relief lighthouse keeper as part of a regular rotation. The journey was delayed a few days by bad weather, and when Harvey and his crew finally arrived, it was clear that something was awry. None of the normal preparations at the landing dock had been made, the flagstaff was bare, and none of the keepers came to greet the Hesperus. The keepers, as it turned out, weren’t on the island at all. All three of them had vanished.

Eilean Mor had its peculiarities. The island’s only permanent residents were sheep, and herders referred to it as “the other country,” believing it to be a place touched by something paranormal. Eilean Mor had long elicited a sort of fearful reverence in its visitors; the main draw to the remote location was a chapel built in the 7th century by St. Flannan. Even those who never prayed were moved to worship while on Eilean Mor. Superstitions and rituals—like circling the church’s ruins on your knees—were adopted by those passing through, and many considered Eilean Mor to have an indefinable aura that could not be ignored.

What the Hesperus crew did find at the lighthouse was a set of perplexing clues. The replacement keeper, Joseph Moore, was the first to investigate, and reported an all-encompassing sense of dread as he ascended the cliff toward the newly constructed lighthouse. Inside, the kitchen table contained plates of meat, potatoes, and pickles. The clock was stopped, and there was an overturned chair nearby. The lamp was ready for lighting, and two of the three oilskin coats belonging to Thomas Marshall, James Ducat, and Donald McArthur were gone. The gate and door were firmly shut.

These clues only led to more questions. Why would one of the keepers have gone out without his coat—and for that matter, why would all three have left together at all when the rules forbade it? Someone needed to man the post at all times, so something unusual must have drawn them out. When Moore returned with his report, Harvey had the island searched. The hunt came up empty. The captain then sent a telegram to the mainland:

A dreadful accident has happened at Flannans. The three Keepers, Ducat, Marshall and the occasional have disappeared from the island. On our arrival there this afternoon no sign of life was to be seen on the Island.

Fired a rocket but, as no response was made, managed to land Moore, who went up to the Station but found no Keepers there. The clocks were stopped and other signs indicated that the accident must have happened about a week ago. Poor fellows they must been blown over the cliffs or drowned trying to secure a crane or something like that.

Night coming on, we could not wait to make something as to their fate.

I have left Moore, MacDonald, Buoymaster and two Seamen on the island to keep the light burning until you make other arrangements. Will not return to Oban until I hear from you. I have repeated this wire to Muirhead in case you are not at home. I will remain at the telegraph office tonight until it closes, if you wish to wire me.

Further investigations also led nowhere, though the lighthouse log book provided a new set of confounding details. On December 12, an entry from Marshall described “severe winds the likes of which I have never seen before in twenty years.” He wrote that Ducat had been quiet and McArthur had been crying, which would have been odd behavior for a man with a reputation as a tough and experienced seafarer. The next day, Marshall reported more storm details and wrote that all three of them had been praying—another odd bit of behavior from well-seasoned keepers in a brand-new, supposedly safe lighthouse. Strangest of all, there were no reported storms in the area on December 12th, 13, or 14—all should have been calm up until December 17. The last report in the book, from December 15, read: “Storm ended, sea calm. God is over all.”

Speculation ran wild. Was it something supernatural? Sea creatures? A case of madness and murder? A government operation? Foreign spies? Aliens? Ultimately, it was evidence outside the lighthouse that provided the most promising lead in explaining what had become of the three keepers. Over at the western landing platform, damage from the recent storms reached as high as 200 feet above sea level. Ropes that were usually affixed to a crate on a supply crane were littered about.

Robert Muirhead, superintendent of the Commissioners of Northern Lights, wrote in his official report:

I am of the opinion that the most likely explanation of this disappearance of the men is that they had all gone down on the afternoon of Saturday, 15 December to the proximity of the West landing, to secure the box with the mooring ropes, etc and that an unexpectedly large roller had come up on the island, and a large body of water going up higher than where they were and coming down upon them had swept them away with resistless force.

While this (or a similar approximation) seems possible, the explanation left considerable room for doubt. The lack of bodies, supposedly calm conditions, and sheer experience and know-how of the lighthouse keepers still hadn’t been accounted for, and never would be. In the years following, other keepers claimed to hear voices in the salty air screaming out the names of Thomas Marshall, James Ducat, and Donald McArthur.

In Mysterious Celtic Mythology in American Folklore, author Bob Curran writes: “For many local people, there was little doubt that they had been spirited into the otherworld.”

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