The Book Switch Theory

[LisaFaginDavis]

Both ideas that Jorge has laid out require significant logical and logistical contortions in order to be plausible.

In order for the Sinapius signature to have been faked by Voynich, he would have had to have written it, scraped it away, and then added the "liver of sulfur" reagent to make it legible, damaging the book in the process. Why go to all that trouble and risk? It wouldn't have added to the authenticity of the provenance...an erased/revealed signature has exactly the same evidentiary value as one that was never erased. Same goes for the Marci annotations on f. 1r. How could (and why would) Voynich have faked those, and then made them fade, and then made them legible again, especially since the Marci letter isn't written in Marci's hand but in his secretary's (meaning that Voynich wouldn't have been able to copy Marci's handwriting based on the letter)? 

Is it all possible? Sure. But it is EXTREMELY unlikely. As I have often said, almost anything is possible, but all things are not EQUALLY possible. The simplest and most clear explanation is that both inscriptions are authentic and that the Marci letter is indeed associated with the manuscript.

The lack of external, supporting evidence does not surprise me at all and does not make me suspicious. Nearly every medieval manuscript has holes in its provenance. That is a feature, not a bug, pertaining to all ancient objects. I would be more suspicious if the provenance had no uncertainties at all.