The Voynich Manuscript by Gerry Kennedy and Rob Churchill

Nudes, triffids and the mother of all riddles

There is a book that no one can read, filled with words written in a cipher that no one can break, or, possibly, a language that no one knows

There is a book that no one can read, filled with words written in a cipher that no one can break, or, possibly, a language that no one knows. This book also contains pictures of things that no one recognises or understands: detailed colour images of plants that can't be identified (but look like a storyboard for an other-dimensional remake of Day of the Triffids), receptacles that might be apothecaries' jars, astrological wheels, and naked women in tubs of green liquid connected via a network of strange "plumbing". It looks a bit like a 16th-century herbal - but only a bit.

The Voynich Manuscript, so called because of the rare books' dealer, Wilfrid Voynich, who, depending on your interpretation, obtained it from a Jesuit monastery in 1912, or created it himself, is one of the most exciting unsolved puzzles in history: the crack cocaine, perhaps, of riddles. It is housed in the Beinecke Rare Book and Manuscript Library at Yale University (which provides photographs of the pages on the internet). Its 246 remaining quarto pages (from an estimated 262) were probably created some time between 1450 and 1600, although no one is sure. Voynich believed it to be the work of Roger Bacon, although contemporary scholars believe it to be later than this. It has never been carbon dated.

The fact that no one has made credible progress with a decipherment is one of the many odd things about the Voynich Manuscript. History provides countless examples of people who have cracked the most complex ciphers and rebuilt lost languages from tiny fragments. People are so good at cracking codes that RSA encryption (the thing that scrambles your credit card number when you buy something online) works on the basis that although the process of decryption is well-known, without the key it can take billions of years.

But no one has had any luck with the Voynich Manuscript. William Newbold, working on the text from about 1919, came up with a crazy mixture of cabalistic Gematria, annagramisation and hocus pocus to decipher a section beginning "Scripsi Rogerus Bacon...", although with the method he used, the text could have said anything he wanted. James Martin Feely attempted a decipherment based on only one plate from Newbold's book (the one with the women paddling in the green liquid). He thought he had found a simple substitution cipher, from Latin to "Voynichese", and part of his translation reads: "Well humidified, it ramifies; afterward it is broken down smaller; afterwards, at a distance, into the fore bladder it comes." Convincing? Not very. In 1945, Leonell Strong came up with a theory that the manuscript was based on a polyalphabetic cipher which he would not reveal in case it fell into the hands of America's military enemies. Part of his translation reads: "When skuge of tun'e-bag rip, seo uogon kum sli of se mosure-issue pedstans..."

Psychologists studying cognitive dissonance could happily wallow in this lot for a long time. But perhaps it's not surprising to find people using the time-honoured method of simply making up what they don't know (even if the fabrication is unconscious). If the manuscript is not the work of Bacon, could it have been created by Edward Kelley and John Dee to further their chances of patronage in Europe? Was it a forgery by Voynich himself, a trained chemist with access to vellum and experience forging documents for the Polish Proletariat movement?

None of the options is truly satisfying. The opinion that it just "doesn't feel like a 20th-century forgery" is common. Yet the Edward Kelley/John Dee hypothesis seems too neat - and too glamorous. Could the manuscript instead be the only remaining document in a forgotten language (as cryptologist William F Friedman believed), perhaps even that of the Cathars? A written equivalent of speaking in tongues? Or is it just a record of someone's migraine visions, or a form of "outsider art"? Nowhere is it suggested that it could have been created by someone exper imenting with psychedelic substances, although this seems like a possible explanation.

This brilliant, page-turning story (which makes The Da Vinci Code seem like a slightly lame round of Hangman) would work in the hands of any authors. Kennedy and Churchill's style is certainly very accessible, although I quickly tired of their use of the term "naked ladies" to describe the women in the illustrations. Still, this book will surely give the Voynich Manuscript an audience beyond cryptologists and internet conspiracy theorists, and that is an important achievement.

Could this new audience even contain the person with the key? Or will this beautiful, frustrating and compelling document simply remain unread?

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