Purple Parchment and the Cave of Smoo

In the year 997, the excommunicated archbishop of Reims sent the Holy Roman Emperor a kingly gift: a copy of Boethius's On Arithmetic written in gold and silver inks on purple parchment. It had the desired effect. As I wrote in The Abacus and the Cross: The Story of the Pope Who Brought the Light of Science to the Dark Ages, my biography of that archbishop, the 17-year-old emperor summoned Gerbert of Aurillac to court with the plea, "Pray explain to us the book on arithmetic." Archbishop Gerbert became the emperor's tutor, friend, counselor--and ultimately, through the emperor's influence, Pope Sylvester II, the pope of the Year 1000.

Earlier in this blog, I described how parchment and ink were made in the Middle Ages. (See "How to Make a Medieval Book, Part I" and "How to Make a Medieval Book, Part II.")

But purple parchment? How did they color the parchment purple? I hadn't given that much thought.

Then the other day, researching something quite unrelated--the Viking settlements in northern Scotland--I stumbled upon the answer.

In 1992, a team of archaeologists led by Tony Pollard excavated four neighboring caves in a narrow inlet in Sutherland, one being the famous Smoo Cave. (See the great website, from which these photos of the cave were taken, at www.smoocave.org) In 2005, Pollard posted their report online at www.sair.org.uk/sair18.

"Smoo" comes from the Old Norse word smuga, which Cleasby-Vigfusson, the classic Old Icelandic dictionary, defines as "a narrow cleft to creep through, a hole." The related verb is smjúga, "to creep through a hole" of which the past tense is smaug. Bells are now going off in the heads of all Tolkien readers--but I won't be following that digression any farther.

Back to Smoo Cave. Surprisingly, I had visited the cave in 1995. Two balding Scotsmen with rat tails and earrings took me on a river raft under a low stone arch, across a pool into which a sun-sparkled waterfall fell. In the dark cave, it was a real surprise. We disembarked in the dry inner reaches of the cave and had a geology lesson. The outer, larger cavern was made by the sea: the hole, wider at the bottom than the top, is a blowhole. The inner caverns were made by an underground river that feeds from a large lake. The waterfall only runs when there’s been rain—today’s fall is last night’s rain.

As Pollard points out, Smoo Cave has been a tourist attraction since at least the early 1700s. One practical-minded traveler described it as "stretching pretty far underground with a natural vault above." Inside, "there is room enough for 500 men to exercise their arms." (I'm imagining jumping jacks here--but maybe he means to practice their shooting?) There's "a harbor for big boats" at the cave's mouth, a pool full of trout, and "a spring of excellent water."

Earlier visitors also valued the cave for its usefulness--not its surprising bright waterfall. Pollard and his crew of archeologists found signs that Vikings had used Smoo Cave as a fishing camp, as well as a place to sit out a storm and repair a boat. They may have stopped here on their way from the Orkney Islands to Dublin. They butchered animals and cooked them. They ate dried fish they'd brought with them. They ground grain. They carved pins and knife handles and other useful objects out of antler and bone.

But the most interesting thing the Vikings did at Smoo and its neighboring caves was collect and crack open whelks. These were not just any whelks, but Nucella lapillus, also known as Purpura lapillus, the source since antiquity of a purple dye. These whelks are not edible, and they were not used as fish bait, Pollard says. "It is clear that purple dye was being extracted from the shells recovered from the cave."

The whelks, Pollard writes, "had been split from the second and third whorl and also split from the shoulder to the base.... This would have facilitated the removal of the animal from its shell to extract the ink."

In 1895, archaeologists found "Purpura-mounds" in Connemara, Ireland. The shells in the mounds had been broken exactly like those in Smoo Cave, though in Ireland there were many more of them. One heap measured 165 by 45 feet. In one square foot, the researchers counted two hundred whelks. Purpura-mounds have also been found in Cornwall, England, but Smoo Cave is the first record from Scotland, although the whelk is common there.

To learn how to make the dye known as Tyrean purple, Pollard refers the reader to the 1919 book, Shells as Evidence of the Migrations of Early Culture by J.W. Jackson. Like Pollard's own report, Jackson's book is available online. (Historical research is so easy these days!)

Jackson, in turn, cites the first-century Roman writer Pliny to explain that "the precious liquid was obtained from a transparent branching vessel behind the neck of the animal and that at first the material was of the colour and consistency of thick cream."

Several kinds of whelks produced purple dye. Small ones were smashed together in a mortar; if large, "the animal was taken out entire, usually by breaking a hole in the side of the shell, and the sac containing the colouring matter was taken out, either while the animal was still alive, or as soon as possible after death, as otherwise the quality of the dye was impaired." The sacs were salted, allowed to sit for three days, then boiled and frequently skimmed. Exposed to the sun, the fluid (smelling like garlic) slowly changed color, from creamy to yellow, green, blue, and finally a purplish red. After ten days, the dye was ready to use.

To dye wool, a clean fleece was dunked into the boiling dye pot and left to soak for five hours. It was taken out, cooled, and the wool plucked off and carded, only to be "thrown in again, until it had fully imbibed the colour" (still smelling like garlic--one reason the wearers of royal purple robes wore so much perfume, suggests Jackson). It took between one and two pounds of liquid dye to color a half-pound of yarn.

To turn parchment purple, Jackson says, the dye was used as a paint, applied with a brush. The "magnificent and expensive style of writing" on purple parchment with gold and silver inks was mostly confined to sacred texts. Jackson cites an English Bible and a Gospel book, another book of the Gospels commissioned by Louis the Pious, king of France from 814 to 840, and a Book of Prayers, "bound in ivory and studded with gems" owned by his son, King Charles the Bald.

It's significant that Gerbert of Aurillac, who would become "The Scientist Pope," owned a mathematical treatise made in this "magnificent" style. The book still exists in the Staatsbibliothek Bamberg in Germany, where it is catalogued as MS Bamberg Class. 5 (HJ.IV.12), but we don't know how it came into Gerbert's possession. Like the gem-studded prayer book, On Arithmetic was commissioned by King Charles the Bald in about 832. But the dedicatory verses apply equally to the young emperor Otto III as to King Charles, and scholars long thought Gerbert (known as a poet) had written them. Otto III may have thought so too, for he answered the gift with a verse.

Join me again next Wednesday at nancymariebrown.blogspot.com for another adventure in Iceland or the medieval world.

Remembering the Scientist Pope

“See those towers?” Costantino Sigismondi points to the two square Romanesque towers crowning Saint John Lateran. “We can imagine Gerbert up there looking at the stars.”

In 2008, while researching my biography of Gerbert of Aurillac, the French mathematician who became Pope Sylvester II, I visited Rome. I met my guide to the city, Costantino Sigismondi, through his website, where he had posted all of Gerbert’s known works. This year, on May 10, Sigismondi has organized a full day of lectures devoted to Pope Sylvester II at Rome’s Sapienza University. On May 12, a mass will celebrate the 1010th anniversary of Gerbert’s death. I wish I could join Sigismondi for the festivities. He's one of those rare people who brings light to the Dark Ages.

Sigismondi, an astrophysicist, teaches the history of astronomy at the University of Rome. In 2000, a friend reading Sky & Telescope chanced upon an article about “Y1K’s Science Guy,” Gerbert of Aurillac. She sent it to Sigismondi, who was astonished. Why hadn’t he known about The Scientist Pope? Sigismondi immediately contacted the Vatican and, with the pope’s support, began planning a series of lectures and events to commemorate the millennium of Gerbert’s pontificate (999-1003), including a grand requiem mass in the cathedral of Saint John Lateran in 2003.

Now we were in the square on the north side of the basilica; we turned to see an obelisk covered with hieroglyphics. “That wasn’t there when Gerbert was pope. We need to go to the Campo Marzio, close to the Pantheon. Ten years before Christ, Augustus put an obelisk there to make a sundial. One of the legends of Gerbert, you remember—William of Malmesbury tells it—is the story of Gerbert and a servant walking through the Campo Marzio, and Gerbert suddenly understands the Augustine obelisk. This is the story of the buried treasure.”

William of Malmesbury, writing in the 1120s, describes not an obelisk but “a statue … pointing with the forefinger of the right hand, and on its head were the words ‘Strike here.’” It was all battered with blows from men who had done the obvious. Gerbert found “quite another answer to the riddle. At midday with the sun high overhead, he observed the spot reached by the shadow of the pointing finger, and marked it with a stake.” He returned at night with a servant and, presumably a shovel. They quickly found themselves in “a vast palace, gold walls, gold ceilings, everything gold; gold knights seemed to be passing the time with golden dice, and a king and queen, all of the precious metal, sitting at dinner with their meat before them and servants in attendance; the dishes of great weight and price.” The palace was magically lit by a sparkling jewel; a golden boy stood opposite it, “holding a bow at full stretch with an arrow at the ready.” Gerbert’s servant, overcome with greed, snatched a golden knife. At once the figures came alive with a roar. The boy loosed his arrow and put out the light. And “had not the servant, at a warning word from his master, instantly thrown back the knife, they would both have paid a grievous penalty.” They covered their tracks and said no more about it.

If this story were set in Reims, I could pooh-pooh it as utter fantasy. But Rome? In 2005, archaeologists were using a coring drill to survey the foundations of Caesar Augustus’s palace on the Palatine Hill. Fifty feet down, the drill plunged into a void. Sending down a camera, the crew discovered a sacred grotto—a round, domed room about twenty-five feet high and twenty-five feet across, covered with mosaics of marble and seashell. In the soft light of the remote-sensing probe, they glittered like gold.

Whether or not Gerbert found buried treasure, if he understood how an obelisk worked as a sundial, he would have understood the Clementine Sundial in the church of Santa Maria degli Angeli. Sigismondi had demonstrated it to me that noon. The church is an architectural pastiche, the interior by Michelango, the exterior a ruined Roman bath. The meridian line of the sundial is not squared with the church—it was added later, the church being chosen for the purpose because of its stable Roman walls and suitable dimensions. The pinhole that lets in the sunlight was set into a great bronze sculpture of the arms of Pope Clement XI (1700-1721) that cuts into one of Michelangelo’s ornate arches. New marble mosaics were set into the floor to create the zodiac images that flank the line, which is made of brass.

“The meridian occurs in this line,” Sigismondi said, putting a blank sheet of white paper near the line so that the faint sun on this cloudy day was more visible. “It’s different for every day. It goes to 12:24 in February, comes back to 12:20 now in March. And back to 12 in October. This is the so-called equation of time. If you take this and put it to local noon time, noon”—when the image of the sun crosses the line—“equals halfway between dawn and sunset.

“If mass is at noon,” he added, “sometimes the transit will happen during mass. If mass is at 12:30, then the faithful can attend mass, the astronomer can do his work, and the faithful astronomer can do both. The priests here are very open. They moved the mass to 12:30 for this reason.” And every day that he works in the cathedral, Sigismondi also takes part in the 12:30 mass, volunteering to read the scripture and take the offerings.

“I am practically the resident astronomer of Santa Maria degli Angeli,” he said. He has held conferences and astronomy classes in the church; on a side table, surrounded by sacred literature for sale, is a one-euro pamphlet he wrote called “Astronomy in the Church.” The pamphlet gives his email address if anyone would like further information on this partnership between religion and science.

Sigismondi has also used the sundial for original scientific research. “I measure this meridian line with video cameras to take scientific information as accurate as possible.  Looking at the sun, it is possible to measure all the parameters of the solar orbit with a precision difficult to achieve with a normal telescope. You can measure the angles of the sun with greater precision because there is no lens—there is no border effect. The border effect of a lens is remarkable. The pinhole, on the other hand, is aberrationless. The only abberation is due to the atmosphere.

“What’s the link between this meridian line and our Gerbert? There’s no real link, because this line was built seven centuries later.

“But it was built by a pope, by a successor of his, Clement XI. He became pope on November 23, 1700. By the first of January, the astronomers were already building this line for him. Only seventy years after the Galileo affair, the pope was building this scientific instrument in the church—and this instrument can distinguish between the Copernican system, with the earth going around the sun, and the Ptolemaic system, with the sun going around the earth. With this instrument of the pope’s, you can prove that the earth goes around the sun.

“And this was possible in Gerbert’s time. If you use only the duration of the seasons, then Ptolemy works. If you can see the image of the sun—as you can with this sundial—then Ptolemy fails.”

Sigismondi speculates that this kind of sundial was the sensational object that Gerbert made for Otto III in Magdeburg—what Thietmar of Merseburg called an horologium, a “time-keeper,” translated variously as an astrolabe, a nocturlabe, a clepsydra, a celestial sphere, or a sundial. “This kind of clock is very easily made by someone like Gerbert,” Sigismondi said, “someone brilliant who understood the idea of using a tube to observe the stars, someone who could make his spheres. A sighting tube is not so different from the type of camera obscura you have here. The function of the church is just to make a dark space so that the light coming through the pinhole can be seen.

“We can’t say that this is what Gerbert made at Magdeburg, but there is room to dream in the history of science. We can’t say he didn’t. And it’s something he could have done. It’s plausible. Gerbert was about four hundred years  ahead of the contemporary people, scientists and scholars included. Many of them understood that he was really outstanding. He was very respected as pope. I would like to see him sainted, or at least blessed. Abbo was sainted, and Gerbert was better than Abbo.”

If anyone could do it, Sigismondi could. A self-proclaimed “faithful astronomer,” he is equally at home in his astrophysics laboratory and in the Vatican; his university website features a photo of him kneeling before the pope. An eager teacher, he had led me on an enthusiastic all-day tour of Rome, highlighting the priest who was carving a new sun to reconstruct a medieval armillary sphere much like the one Gerbert had made; the Jesuit who had originated the field of astrophysics; the pope who had studied the dimensions of the sun.

The more time I spent with him, the more he seemed like Gerbert himself—Equally in leisure and in work we both teach what we know, and learn what we do not know. Or, perhaps like Gerbert’s beloved friend, the sweet solace of his labor, a man with the same first name: Costantino Sigismondi was Gerbert’s twenty-first century Constantine, who would keep the story of The Scientist Pope alive.

Join me again next Wednesday at nancymariebrown.blogspot.com for another writing adventure in Iceland or the medieval world.

The Book of the Icelanders App

The press calls it the Incest App. It's the winner of a contest sponsored by DeCode Genetics, which oversees the Icelandic genealogy database called Íslendingabók, or "Book of the Icelanders" (also the title of the first history of Iceland, written in about 1120 by Ari the Learned).

The database was set up in the 1980s using Iceland's extraordinary genealogical records. DeCode matches it with health records and genetics data to research the causes of disease. As payback to the nation for using its heritage in this way, DeCode has made Íslendingabók freely available to anyone with an Icelandic kennitala, the equivalent of a Social Security number, to use to trace his or her ancestry back to the first settlers of Iceland in the late 800s.

Several of my Icelandic friends have shared their results with me. I have been warned (tongue-in-cheek, I hope), "Be careful what you say about Snorri Sturluson. He was my ancestor," for example.

The new app doesn't go back that far. If two Icelanders bump phones, it finds each kennitala, pulls up the records of their grandparents, and beeps if there's a match. (A future version might search back to great-grandparents.)

It's the bump and the beep that have the press excited. The app developers named it the "Incest Spoiler."

That provoked a bit of a rant from Icelandic writer Alda Sigmundsdottir on "The Iceland Weather Report" Facebook page. "I suppose it was a clever ploy to add the incest dimension--the guys who wrote it [the app] did that, and the international media gobbled it up, swallowed it whole, and are now ravenous for more," she wrote. "I probably shouldn't let it get on my nerves, but it totally does." If you don't know who your cousins are, she points out, it means you--and the record-keepers at Íslendingabók--don't know who your father is, and no app is going to help you.

What Is Incest?
But there's another question to ask. Is sleeping with your cousin incest? It depends who (and when) you ask. Incest is a cultural phenomenon.

Sex with your father, mother, brother, or sister is uniformly considered incest--and wrong.

But in much of the U.S. today, you can not only sleep with your cousin, you can marry him or her: It's legal in 25 states. It's not even thought to be a bad idea for cousins to have kids. According to a 2009 article in the New York Times, "For the most part, scientists studying the phenomenon worldwide are finding evidence that the risk of birth defects and mortality is less significant than previously thought." Laws preventing cousin-marriages, says one researcher are "rooted in myth" and amount to "genetic discrimination akin to eugenics or forced sterilization."

Those myths go back to Roman times, but they took a bizarre turn in the Dark Ages when the Christian Church decided to take control of marriage and make it a sacrament, not just an economic transaction between two families.

Through the 700s, the Church followed Roman law: Marriages "within four degrees" were incestuous, and so forbidden. You counted the degrees by counting up from the bride to the common ancestor and then back down to the groom. First cousins equal four degrees.

In the early 800s, the Church changed the definition of incest from four degrees to seven. It also changed the way degrees were counted. Now you counted in only one direction: from the bride (or groom) back to the shared ancestor. Seven degrees meant that it was incest if the couple shared a great-great-great-great-great-grandparent. In the late 900s, this caused a crisis for King Robert the Pious of France: Under these rules, there was no woman of sufficient rank in Europe whom he could legally wed. So he ignored the rules, married his second cousin, and was excommunicated. He ignored that too.

Snaelaug's Story
In Iceland, the Church's rules on incest were not enforced until the late 1100s, but by then they were even stricter. I give one example in my book Song of the Vikings, a biography of the chieftain and writer Snorri Sturluson.

One of Snorri's mistresses was Gudrun, whom he called in a poem "lovely as a swan." Gudrun was the illegitimate daughter of a woman named Snaelaug, who had been happily married to Snorri's uncle Thord Bodvarsson—until Bishop Thorlak of Skalholt intervened.

Snaelaug had given birth to Gudrun quite young, saying the baby's father was a cowherd. Her own father, a priest, forgave her and sent her away to a relative's, where she met young Thord, who was the future chieftain of Gard and Snorri's uncle on his mother's side. Thord and Snaelaug fell in love. Thord sued for her hand in marriage, and with their families' approval they were wed. They were very happy and had three sons.

In 1183, when Snorri was five and Gudrun at least three, news came from Norway that a young man named Hreinn had died, and Snaelaug let it slip that Hreinn, not the cowherd, was really Gudrun's father.

Hreinn and Thord were third cousins: They shared a great-great-great-grandfather. Even in a culture as obsessed with genealogy as medieval Iceland's, this did not set off alarm bells in Snaelaug's head. Yet according to the Church's byzantine incest laws, it meant that she and Thord could not be married. Their relationship was incestuous because of her previous one-night-stand with her husband's third cousin.

Snaelaug's father, a priest who should have known these laws, did nothing about it. For this he was called on the carpet by Bishop Thorlak. The soon-to-be-sainted Thorlak "was so inspired by faith in God," a saga says, that he marched up to the Law Rock during the yearly parliament at Thingvellir "with all his clergy and swore in public that this marriage contract was contrary to the Law of God. He then named witnesses, declaring the union null and void." He excommunicated "all the parties to the contract" and declared that any children Thord and Snaelaug had after that moment would be illegitimate.

They argued. They pleaded. They ignored the bishop. But finally they had to part. Thord went home to his family farm of Gard, while Snaelaug raised her children at her family farm of Baer. From Baer to Snorri’s estate of Borg was about ten miles. Since his uncle Thord had given Snorri half his chieftaincy, the two men were in close contact. Snorri had ample occasion to travel to Baer to meet with his uncle—and to be smitten with love-sickness one day when he walked in upon slender Gudrun combing her hair.

Join me again next Wednesday at nancymariebrown.blogspot.com for another adventure in Iceland or the medieval world. And don't forget to enter the raffle for a free, autographed copy of Song of the Vikings. I'll be announcing the winner on May 1. For details, click here.

The Flat Earth Error

How many times have you heard it said that people in the Middle Ages thought the world was flat?

When I was working on The Abacus and the Cross, my biography of the Scientist Pope, I was thrilled to find a map of the world drawn shortly before the year 1000. This map appears in a standard medieval geometry textbook. It is drawn as a circle, and a caption at the top explains that the circle depicts one hemisphere of the globe. Around the edge of the circle, another caption refers to the method devised by Eratosthenes in 240 B.C. for calculating the circumference of the earth. That method was well-known to medieval scholars, who routinely referred to the earth as “round as an apple” or an egg.

This map of the spherical world from before the year 1000 is in the Staatsbibliothek Berlin (Preussicher Kulturbesitz, Phill. 1833 (Rose 138), fol. 39v). It was published in 1996 in Autour de Gerbert d’Aurillac, le Pape de l’an Mil, edited by O. Guyotjeannin and E. Poulle.

Yet in the late 1980s, historian of science Jeffrey Burton Russell, author of Inventing the Flat Earth, found the “fact” that medieval people thought the earth was flat in a 1983 textbook for fifth-graders, a 1982 text for eighth-graders, and in the 1960, 1971, and 1976 editions of the college textbook, A History of Civilization. He even found it in the bestselling 1983 book, The Discoverers, by the former Librarian of Congress, Daniel Boorstin.

Two writers share most of the blame for this: Petrarch and Washington Irving.

The Italian writer Petrarch (1304-1374) is known for two things: developing the sonnet, and coining the term “the Dark Ages.” Sometimes called the first humanist, Petrarch divided history into Ancient (before Rome became Christian in the fourth century) and Modern (his own time). Everything in between was dark. Writes Russell, “The Humanists perceived themselves as restoring ancient letters, arts, and philosophy. The more they presented themselves as heroic restorers of a glorious past, the more they had to argue that what had preceded them was a time of darkness.” (Stephen Greenblatt, in his popular book, The Swerve, is still making this argument; I’ll discuss that in a future blog post.)

The humanists also had a political motive. The Italian cities wanted to break free of the Holy Roman Empire. That meant denying all the contributions to civilization promoted by forward-thinking emperors such as Charlemagne or Ottos I, II, and III (patrons of the Scientist Pope), as well as those of the Church itself. Petrarch and his fellow humanists saw no contradiction in the fact that all of the ancient “letters, arts, and philosophy” they “discovered” had been copied, and so preserved, in the scriptoria of monasteries and cathedrals through the thousand years of the so-called darkness.

A clearly spherical earth, in the mid-14th century Bible Historiale of John the Good (BL MS Royal 19 DII).

Skip to the American writer Washington Irving (1783-1859). In his time, studying the Middle Ages was considered “a ridiculous affectation in any man who means to be useful to the present age,” according to Henry St. John Bolingbroke, whose political writings influenced Thomas Jefferson, among others.

This attitude made it easy for Washington Irving, in The Life and Voyages of Christopher Columbus, to rewrite the discovery of the New World in 1492. In the 1820s, having just published the stories “Rip Van Winkle” and “The Legend of Sleepy Hollow” to popular acclaim, Irving went to Spain, where he was given access to original documents about Columbus. Finding the truth a little “dry,” in his words, he decided his hero’s story required more dramatic tension. Writes Russell: “It was he who invented the indelible picture of the young Columbus, a ‘simple mariner,’ appearing before a dark crowd of benighted inquisitors and hooded theologians at a council of Salamanca, all of whom believed, according to Irving, that the earth was flat like a plate.”

What in fact they believed—and the original records of the council still exist—was that Columbus was fudging his numbers. Using the standard method given in medieval geometry textbooks—and on the map from before the year 1000—the Council of Salamanca calculated the circumference of the earth to be about 20,000 miles (it is actually about 25,000 miles) and the distance between one degree of latitude or longitude at the equator to be 56 2/3 miles (it is actually 68 miles). Columbus thought the earth was much smaller. He said a degree was 45 miles and the span of ocean between the Canary Islands and Japan only 2,765 miles—twenty percent of the actual figure. If he had not providentially bumped into America, Columbus would—as the experts in Salamanca believed—have run out of food and fresh water long before he reached Japan. Columbus, says Russell, had “political ability, stubborn determination, and courage” on his side. His opponents had “science and reason” on theirs.

Washington Irving took science and reason and gave them to Columbus—and it was Irving’s version of history that became common knowledge. Why? Americans, says Russell, “wanted to believe that before the dawn of America broke, the world had been in darkness.”

You can see more medieval images of a round world on Donna Seger’s blog, Streets of Salem: http://streetsofsalem.com/2011/06/13/the-medieval-world/ She writes (sadly): “every year I poll the incoming freshmen in my World History class about what they were taught in primary and secondary school and every year more than half of them raise their hands in support of the medieval flat earth.”

Join me again next Wednesday at nancymariebrown.blogspot.com for another writing adventure in Iceland or the medieval world.