The Mystery of the Voynich Manuscript
newyorker.com
newyorker.com
Rugg (2004) claims that words might have been generated using a ‘Cardan Grille’ – a way to deterministically generate words from a table of morphemes.
(Gordon Rugg. 2004. The mystery of the Voynich Manuscript. Scientific American Magazine.)
If you know there was a reasonably fast way to produce the content which has exactly observed properties, why searching for some more complicated explanation?
But why generate all that text using a cardan grille?
They use some Java wrapper which is pointless if you have a native Djvu plugin.
1) writing gibberish 2) writing in a coded language to hide the message
Neither of these would be the same as a coordinated attempt to communicate, even if it were asynchronous.
The first is that even in medieval times parchment wasn't cheap. It wasn't like anyone could get there hands on enough to make 200 pages of gibberish unless they were a relatively wealthy doodler.
The second is that were it in code, the sophistication of ciphers in the 1500's was hot high, and generally quite susceptible to the sort of forensic analysis that is covered in the ISI paper linked in the comments. As far as I am aware, the only cipher system, known at that time, that would not succumb would be a one time pad. And in the case of an OTP cipher it would reveal itself in other ways (lots of entropy in the words).
If it isn't clear, I do agree that it 'being in code' is the most likely reason it has not been deciphered, but that the cipher of that time is not breakable given what we know of 'plain text' of those times (the various languages it could have been written in) makes me wonder how we would fare against an alien communication (should we ever pick one up).
If instead we used a one time pad, we wouldn't have much luck reaching out to aliens. This points to the more likely scenario that the manuscript isn't encoded at all (gibberish) or it was meant to be understood by only one person.
But consider: > The first person said to have owned the manuscript was the Holy Roman Emperor Rudolf II, who reportedly was intrigued enough to buy it from its previous owner for six hundred ducats, around ninety thousand dollars in today’s money. (According to the manuscript’s radiocarbon dating, the book was already nearly two centuries old at the time of his purchase.)
Supposing it's random — perhaps the person who made it originally, two hundred years earlier, hoped to charge a similar price from either a gullible patron like Rudolf, or someone who hoped to find a greater fool like Rudolf?
From http://www.isi.edu/natural-language/people/voynich-11.pdf, linked in another comment.
That's quite the logical leap you took there. I think it's far far more likely that a human wrote this document.