100 sheets of stolen vellum

[Jorge_Stolfi]

They were a display of wealth, knowledge and power as well as a collection of valuables (and gifts). Luxury manuscripts (most of the ones that survived the times) were collectibles, not literature to be used frequently. Certainly it was possible to access these works, but not for commoners who couldn't even afford decent parchment.   

All I meant is this: even if Taccola's notebook was in the imperial library, that does not imply that no copies were made.  Someone with good enough standing in the Court could have been allowed to make a copy, either in situ or by borrowing it. 

Even if the VMS Author could not do that himself, he could have obtained a copy of that copy. 

But I gather from your comments that it is highly dubious whether that notebook was indeed ever in Sigismund's library.   So this point may be moot anyway.

The Standard Provenance theory says that Rudolf gave the VMS to Jacobus out of gratitude.   But I gather that there is a variant where Jacobus would have borrowed the book from Rudolf, but when Rudolf died he "forgot" to return the book, and added it to his own library.  (This variant might explain why neither Baresch nor Marci mentioned Jacobus: they feared that the Court would demand the book back, if it was identified as such.  And so Baresch himself would have erased Jacobus's ex-libris from f1r.)  

Anyway, this variant would be an example of someone with good standing at the Court borrowing a valuable book from a royal library.

Also such works were not copied from libraries. They were compiled in workshops that had text on scrolls and stock imagery, usually on wooden boards (Pinakes). Hence the often substantial differences in text and imagery between copies.

That was the case for most copies that were "industrially" produced, either for sale on the market or under commission from people with enough money.  The majority of manuscripts that have survived are of that class, both because they were the majority to begin with, and because they had better chances of surviving due to their better quality.

But there were also many manuscripts created outside of those "factories".  If a scholar saw an uncommon book in the library of a colleague, monastery, university, etc., and wanted to have a copy, he would not hunt for it in the marketplace.  He would borrow the book and make a copy himself, or recruit a scribe to do so.  Students would do that by borrowing from colleagues, professors, or the school's library. 

Check these You are not allowed to view links. Register or Login to view..  I suppose that the Cambridge and Vatican copies were produced "industrially" for sale on the textbook market.  But the others look like they were made privately for the owner's own use.  

The Paris one is interesting because it has space for ornate capitals, but not the capitals themselves.  I suppose that it was made by a professional scribe who was hired to copy the text only, but he left those spaces because it was his modus operandi.

The Erfurt one is interesting also because, even though the execution is terrible, it uses a different font for the first line of each section/paragraph.  Which reminds me of the use of puff gallows on the VMS...

The cost of more decent parchment would not have been prohibitive, not to speak of IGA.

The only estimate for the cost of vellum that I know, based on cost of living, is still the equivalent of US$2 per folio.  Thus 100+ folios would have been US$ ~200.  That could have been way too much for an old unemployed scholar.

The ingredients for iron-gall ink would have cost much less than that -- if they were available at all. 

Or just use paper!

The VMS Author surely wrote the book on paper, before he decided to make a vellum copy.

I stand by my point that whoever made the VM had access to a vast and top-level source of imagery.

I agree, except for the "vast".  We have identified less than a dozen books so far as plausible sources for the imagery.  Those may have been all the books that the Scribe had available to serve as "inspiration" for his drawings.   It does not seem like he had to find the right book among a thousand...

Who made parchment of VM quality and in which environment was such parchment most likely to be found?

AFAIK, vellum and parchment were made in what were basically specialized tanneries.  The process is very much the same as that for making leather. (And would stink just as bad.)  Since it is a labor-intensive process, there must have been thousands of "cottage industries" all over Europe, each churning out a few large sheets per day, on average.

There would not be a shortage of raw hides to fill the demand for vellum, so vellum makers could be picky and reject hides with large visible defects.  But some defects may have been revealed only during manufacture, or could be accidentally created by the stretching, scraping, and polishing.  So I bet there would be some amount of low-quality vellum available in the market, for a discount price.

And there may have been second-hand vellum on the market that had been bought in bulk by a "manuscript factory" but was not used because it got damaged by humidity or whatever.

And then there is the possibilty that the Author scavenged blank folios or bifolios from other books...

All the best, --stolfi