Why the Codex Gigas Is Known as the Devil’s Bible

In July 1648, near the end of the Thirty Years’ War, Swedish forces swept through Prague, seizing some of the city’s most prized possessions. Among them was the Codex Gigas, the largest surviving illuminated manuscript of the European Middle Ages. Nearly 3 feet tall, more than a foot and a half wide, almost 9 inches thick and weighing about 165 pounds, the Codex Gigas is an extraordinary work of craftsmanship.

But it’s not the book’s size alone that has solidified its enduring reputation. Inside, sprawled across a single page, is a full-length illustration of what appears to be Satan, a feature that has made the manuscript a source of fascination and fear for centuries, and earned it the nickname the Devil’s Bible.

The Codex Gigas, Latin for “giant book,” is now housed at the National Library of Sweden, where it is kept under controlled conditions. Scholars believe it was created in the early 13th century, sometime between 1204 and 1230, in the Kingdom of Bohemia, in what is now the Czech Republic.

“It’s difficult to determine exactly when or where manuscripts were copied, as dating often relies on handwriting analysis and any surviving notes,” says Hugh Houghton, a professor of New Testament textual scholarship at the University of Birmingham. One such note, written on the first page of the Codex Gigas, names the Benedictine monastery of Podlažice as its earliest known owner and records that in 1295 it was pledged to another monastery, likely as collateral.

Its more than 300 surviving pages are made from the skins of roughly 160 animals, either calves or donkeys, each prepared into smooth membrane. Research by paleographer Michael Gullick suggests it was the work of a single scribe, based on the uniform handwriting and use of one type of ink made from crushed insect nests. Every letter, line and illustration reflects the same steady hand, an achievement that implies decades of dedicated work.

Between the artistry and writing, the National Library of Sweden estimates “the manuscript probably took at least 20 years to finish, and could even have taken 30." The scribe who wrote it may have been Herman the Recluse, a monk mentioned in monastery documents, though this remains uncertain.

The manuscript itself is like a portable library, pairing biblical texts with historical, medical and reference material. “In Latin, it’s quite common to find complete manuscripts of both the Old and New Testaments,” says Houghton. “What makes the Codex Gigas unusual is that it not only contains these scriptures, but also a wide range of other works.”

These include Antiquities of the Jews and The Jewish War by the first-century historian Flavius Josephus, Isidore of Seville’s Etymologiae (a medieval encyclopedia), medical treatises by Constantine the African, calendars, exorcism formulas and magic spells and the Chronica Boemorum, a history of Bohemia. This unusual combination of religious scripture and secular knowledge has prompted speculation that the Codex Gigas was intended to be an all-in-one compendium of human understanding.

The portrait of the Devil appears about halfway through the Codex Gigas, opposite an equally large image of the Heavenly City—paradise on one side, a crouching horned figure on the other. The Devil, crudely drawn in muted tones compared with the manuscript’s vivid illuminations, fills nearly the entire page, making it the largest known medieval image of Satan. Some scholars believe the placement was deliberate, a reminder of the choice between salvation and damnation.

Yet the Devil of scripture was far less imposing. “He first appears in the book of Job, and he’s pictured just like one of the other angels,” says pastor and biblical scholar Robin Nettelhorst. He appears only twice more in the Old Testament. “He’s such a minor figure in the biblical text that we don’t even know what his name is,” Nettelhorst explains. The horned ruler of hell is a much later invention, influenced by centuries of storytelling.

That storytelling helped shape the lore around the Codex Gigas. According to legend, a monk condemned to be walled up alive for breaking his vows begged for mercy by promising to create a book that would glorify the monastery forever—and to finish it in one night. As midnight neared and the work remained far from complete, he called upon the Devil for help. In return, he painted the Devil’s portrait in gratitude.

After leaving Podlažice, the Codex Gigas circulated among monasteries until 1594, when Holy Roman Emperor Rudolf II, known for his fascination with alchemy and the occult, added it to his collection in Prague. Swedish troops seized it during the capture of the city and brought it back to Stockholm, where it entered the royal library.

In 1697, fire engulfed Stockholm’s royal castle, consuming much of the library. To save the enormous Codex Gigas, a rescuer hurled it from a window. The fall spared it from the flames but tore its binding and destroyed several pages, including a section thought to contain the Benedictine rules. On New Year’s Day 1878, the manuscript was moved to the newly built National Library in Stockholm, where it remains today. In 2007, the Codex Gigas returned to Prague for the first time in 359 years, drawing record crowds eager to glimpse the legendary Devil’s Bible.

In the end, the Codex Gigas stands at the crossroads of faith, fear and folklore. It is a testament to medieval ambition and craftsmanship, a record of both sacred devotion and human curiosity, and a reminder that sometimes the most enduring history is the history we can’t quite prove.