Sometimes called 'the most mysterious book in the world', this is a unique volume now in the Beinecke at Yale about which almost nothing is known: not its author, or when it was written, or the alphabet it uses, or even what language it's written in. No other example of this writing has ever been found, so there's nothing to compare it with.
Since the manuscript re-surfaced in 1912 (having first turned up in the 1630s, only to vanish again in the 1660s), there have been many attempts to crack the code and translate the text, all to no avail. One school of thought held that it'd been written by Friar Roger Bacon* [d.1294] and later owned by Dr. John Dee** and, possibly, the notorious Edward Kelley, but there was no proof of any of this.
Now, at last, we have something more-or-less definite: carbon-14 dating that shows the paper it's written on dates from the early 1400s -- that is, a little after Chaucer's time, and more than a century after Bacon's death. And it looks like the ink and coloring for the many illustrations and illuminations and decorations are also from the first half of the same century. So that gives us a good idea of the time period, but brings us no closer to knowing who wrote it and what it says.
It's my private belief that it's not only an invented script but also an invented language (like a Sindarin text in tengwar), probably only ever known by one person. I doubt it'll ever be translated, unless another, more accessible, piece in the same script shows up (and after ninety-nine years of searching, and two World Wars devastating Europe, that seems pretty unlikely). Still, it's a tantalizing possibility . . .
Here's the link:
For anyone who wants to know more, I'd recommend M. E. D'Imperio's THE VOYNICH MANUSCRIPT -- AN ELEGANT ENIGMA (Aegean Park Press, n.d. [circa 1976]), which surveys all that's known and much that's speculated about the manuscript, summarizing the major arguments that have been put forth in favor of this or that theory (including several purported translations). Too bad there's no proper facsimile edition: a few pages are available online, but they're only a fraction of the whole. Not that I cd read it, of course, but it'd be nice to get a sense of the whole for once. And it'd be an interesting thing to have around -- after all, though I've only barely skimmed it, I prize my big facsimile of Casaubon's 1659 edition of A TRUE & FAITHFUL REVELATION OF WHAT PASSED FOR MANY YEARS BETWEEN DR. JOHN DEE . . . AND SOME SPIRITS, this being a transcription of Dee's sessions with Edward Kelley, who claimed to be receiving messages (sometimes in Enochian) from angels.
*one of the two heroes of one of my favorite novels, John Bellairs' THE FACE IN THE FROST, as well as the main character of Roger Greene's famous but little-read old play FRIAR BACON & FRIAR BUNGAY [1592?], which tells the story of The Brass Head. In real life, he wrote a wonderful little tract called ON THE NULLITY OF MAGIC, which anticipates Reginald Scot by more than three hundred years.
**one of the two most gullible men who ever lived.