12th century monks used seal skin to bind books — despite not knowing what a seal looked like

New research from the University of Cambridge sheds light on the use of seal products across Europe during the middle ages, including the use of seal skins to bind and decorate religious texts.

Researchers told CBC News the use of seal skins as a book binder starts around the 12th century with the creation of a French abbey — or monastery — by Bernard of Clairvaux, a monk responsible for the early expansion of the Cistercian Order throughout Europe.

"What I'm more interested in is the bindings. They have a very specific structure that makes them very peculiar, and that you can recognize. And it's very typical from the 12th and 13th century," Élodie Lévêque said Friday.

"Paper didn't exist at the time, so it's all made with parchment. So skin, leather, and it's also made of wood."

When people began to examine the bindings, researcher Matthew Collins said scholars were quick to debate what they were made of. They had expected something like boar or deer skin, but analysis of proteins brought the surprising discovery.

"It turned out the fingerprints matched seal skin," Collins said. "You're talking about movement of skins over great distances. From very far away, into northern France."

Lévêque said she was especially taken aback by the finding of seal skin, saying she had never even considered it as an option.

Why? Because, she said, Cistercians of the day had likely never even seen a seal before.

"We think the monks didn't actually really know that they were using seal skins…. In the 12th century, there was no word for that in French," she said.

"[They get it] either through trading, cause the north trading routes go all the way exactly where we find the books…. Otherwise, maybe through the church ties. Because there was one text in the 13th century that mentions the fact that in Rome, they had too many seal skins and didn't know what to do with it."

Drawings also found during the research process illustrate what Cistercians perceived seals to look like — a four-legged sea monster with the body of a calf and a tail.

Another reason seal skins — and, in particular, the pelts of younger seals — were used was because of the colour white, Collins said.

Known as the white monks, Collins said Bernard of Clairvaux and Cistercians were quick to move away from the traditional brown. Lévêque said the bindings also show meticulous work was done to preserve the image of white books in the monk library.

"There is like a patchwork, you can see sewings in the fur. And I believe they were removing the darker spots to sew a new, whiter spot in it," she said.

Lévêque said around 100 books bound with seal skin were found, many of which are located in the French areas of Troyes and Montpellier.

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