“The academic world is a jungle,” wrote Schinner, who first applied statistical analytics to the manuscript more than a decade ago, “and like in any jungle, it is not recommended to show even potential weakness.”

Read: Has a mysterious medieval code really been solved?

All we know for certain, through forensic testing, is that the manuscript likely dates to the 15th century, when books were still mostly handmade and rare. But its provenance and meaning are uncertain, making it virtually impossible to corroborate any claims about its contents against other historical materials.

So why are so many scholars and scientists driven to solve the puzzle? For many, it’s the ultimate opportunity to prove their analytical skills in their given field. For others, it’s a chance to test promising new digital technologies and artificial-intelligence advances. And for some, it’s simply the thrill of the hunt.

The manuscript was acquired in 1912 by Wilfrid Voynich, a Polish rare-book dealer. Resembling a modern book rather than a scroll, it is full of looping text handwritten in an elaborate script, accompanied by lavish illustrations. The find failed to make Voynich rich, but the manuscript has continued to make headlines for more than 100 years, challenging researchers in many fields, including linguistics, botany, and machine learning. It now resides at the Beinecke Library at Yale University.

At first, it mainly attracted humanities scholars. In 1921, William Newbold, a philosopher at the University of Pennsylvania who had an interest in cryptography, claimed that a 13th-century friar wrote it as a scientific treatise. Newbold believed that each arcane letter was actually a collection of minuscule symbols readable under proper magnification, which would have meant the microscope was invented centuries before we thought. After Newbold’s death, John Manly, an American literature professor and fellow code breaker, disproved Newbold’s theory, showing that his methods were arbitrary and scientifically unreliable.

William and Elizebeth Friedman, two founding figures in modern cipher-breaking, continued to apply code-breaker techniques to the manuscript. Though they studied other texts and were recruited to crack messages during both world wars, they were never able to land on a solution to the Voynich.

During World War I, the Friedmans had to perform their calculations by hand, but in the following decades, IBM’s punch-card tabulating machines made the process much faster. Working with the National Security Agency when it was formed in the 1950s, William and other code breakers pursued an interest in the medieval manuscript (there’s even a copy of it in the NSA’s internal library). Because the manuscript was unclassified, Cold War code breakers could use it to illustrate cutting-edge computational analysis techniques to their colleagues without using real Soviet messages.