The Book Switch Theory

[Jorge_Stolfi]

Once he knew Horcicky was Sinapius was Tepenenc, then this would plausibly lead him to finding other references to Tepenenc... perhaps his signature, with that form... with no "Horcicky"?

While Wilfrid himself may have had only limited information about Jacobus, once he saw Raphael's claim in Marci's letter it seems quite possible that he asked contacts in Prague to find people who could have been Marci's "good frend", or (if he had already identified the latter) the owner(s) before Baresch.  They would be people connected to the Bohemian Court between 1300 (when, in Wilfrid's mind, Rudolf I would have bought the book) and 1600 (just before Barschius acquired it) with enough status to have received that highly valued book as a gift.  

Those contacts surely would have found Jacobus, among many others, and learned all his names.  And his profession, and why Rudolf II gave him the title, etc.

And thus Jacobus would have been one of the most likely candidates for the missing link.

And, if and when Wilfrid decided to forge concrete evidence of such a link, he would have asked those contacts to find any book with an ex-libris of one of those candidates, and send him a faithful copy of the latter.  

And book #4 must have been the easiest one to find: at the Czech National Library, housed in the building of the former Clementinum, the Jesuit college that inherited Jacobus's estate.

And, curiously, the VMS #19 "signature" looks identical -- not just similar -- to that #4 "signature".  Which is completely different from the "signatures" on #7 and #18, which were at the Strahov Monastery; and from the signature on #40, rat Charles University -- which is the only one that matches Jacobus's legal "manu propria" signature.

All the best, --stolfi