The Book Switch Theory

[ReneZ]

OK, but then that mistake makes no difference to any of the provenance/switch/forgery theories, does it?  

It is fundamental. Just talking about the book switch theory here.

All the way from the beginning until 1918, Voynich did not bring the letter in connection with Rudolf's Prague, but with Roger Bacon (Paris) and Rudolf I (until 1290, various places in Germany).

He only started thinking about Rudolf II and his court in 1918-1919, after he was finally convinced of his mistake.

You correctly pointed out that the two references to Rudolf's court in the letter and the MS are probably a bit too much of a coincidence, but Voynich was not making that connection.

Anyway, there would be a far greater coincidence that cannot be explained away.

The Marci letter says that the previous owner left him the book in an inheritance, and that owner also wrote to Kircher. Now we don't know from how many people Marci inherited stuff, but one person from whom he did inherit was Barschius, and Barschius indeed wrote to Kircher, and the one surviving letter describes a book that closely fits the Voynich MS. 

That is too much of a coincidence.