If you’re the type of person who loves solving puzzles and cracking codes, there’s a book on display at the Folger Shakespeare Library that you may want to think twice about before looking at.

“The Voynich Manuscript has led some of the smartest people down rabbit holes for centuries,” says Bill Sherman, curator of the new exhibit “Decoding the Renaissance: 500 Years of Codes and Ciphers.” “I think we need a little disclaimer form you need to sign before you look at the manuscript, that says, ‘Do not blame us if you go crazy.’ ”

Roughly 250 pages of mysterious script wrapped around illustrations of naked women, imaginary plants and astrological charts, the Voynich Manuscript was written in the 15th century, according to carbon dating. The script has baffled everyone who has tried to decipher it, including William Newbold, a University of Pennsylvania professor at the turn of the century who spent the final years of his life looking at the text with a magnifying glass, trying to read tiny squiggles within the letters.

The eminent cryptographer William Friedman (whose work — including his answer to Germany’s “Enigma” machine — is at the center of the Folger exhibit) also sunk years into deciphering the manuscript. When he wasn’t busy debunking the theory that Francis Bacon had left secret messages proving that he was the real author of Shakespeare’s plays or cracking Japan’s code during World War II, Friedman performed a statistical analysis of the Voynich Manuscript.

He and a cast of code-breakers, including his wife Elizebeth, investigated how often various characters and “words” occurred within the manuscript. They found that while the letters weren’t randomly distributed — for example, some almost always occurred at the beginning of words — the “words” they formed weren’t deployed in a pattern reminiscent of any known language. A single “word” might appear three times in a row, for instance.

“The Friedmans eventually decided that it was a totally made-up language,” Sherman says.

If you’re beginning to think the book is a 15th century hoax, you’re not alone. Still, the carefully prepared vellum and the neat handwriting that must have taken at least two scribes many months to complete suggest otherwise.

Since the Friedmans, plenty of people have sunk sleepless nights into the Voynich manuscript, with little to show for their labor. However, every so often, the codex divulges something that keeps them going. Last year, a team of researchers found evidence that particular words only appeared near certain types of illustrations, and just last month a linguistics professor claimed to have translated 14 characters from the script, revealing the meanings of a handful of words.

Intrigued? Take a peek at the full text online, or visit the actual manuscript at the Folger. Just don’t say we didn’t warn you.

Folger Shakespeare Library, 201 E. Capitol St. SE; through Feb. 26, free.

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