Rosettes and Astrology

[Bernd]

First, most plants have no real‑life counterparts, and the supposed quack doctor could at most surprise his patients with these drawings. Second, if everything in VMS is completely meaningless, then it’s unclear how he used it.

For me it's rather simple.

A woman comes to the charlatan. She says she suffers from, let's say, painful menstruation.

And then he says something like:
"Menstruation you say? Let me think"

 He makes a very clever face expression and starts browsing the folios with plants. Then he stops at one folio. 
"Oh, this one should work. You have come to the right man, my dear lady. I have a great remedy. It's Florabundus Absurdus. It is a very rare flower, it grows only in Getshemane garden in Jerusalem when our Lord Jesus prayed before His crucifixion. It blooms only on the day of the Lord's resurrection. But by chance I happen to have this miraculous ointment made from its petals which is great for menstruation. And for you I have a special discount price..."

Any charlatan must be good at talking. So our man will be able to make hundreds of similar stories on the fly.

Each time when a sick man comes to him, he will have a perfect remedy for his problems. He will browse plants, consult recipes and astrological charts and pretend that he is reading the manuscript written in some occult language. But he will be just faking it and telling people exactly what they want to hear.

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By the way, a wandering charlatan theory may explain why the last page probably contains some charm with German vibe (pox leber) while the month names under Zodiac signs are written in some variant of French or Occitan. 
The charm could be written for some client on a marketplace in a German town. Then our charlatan moved to France where he lost his almanac. Some local man who got it tried to understand it and started with signing the Zodiac signs in French.

I don't think the charlatan prop book / almanac hypothesis is plausible. The VM contains an almost fractal level of details. It is unnecessarily complex in order to fool others who'd only see the contrents from afar, both in imagery and text. Why compile such a paracosm from a multitude of sources in such a weird way? On top if that, look at the drawings. Would you consult a doctor that's working with a book with this sort of imagery? That's nothing you'd show around in a 15th century marketplace without getting yourself into serious trouble. If anything, it may have been something to fool very wealthy and influential people - in private. But I also don't believe that. It may very well be that the VM is some sort of 'imitation' of real manuscripts the author had seen, but I think it was more something of a personal art project, not meant to be read by or shown to others - or to fool them.

In any case, I think we can agree that the author cobbled together the imagery from a multitude of sources he'd come across, and re-used the elements he liked within the VM. I think this is also compatible with the idea that the author was building some sort of personal fantasy world in which the drawings may or may not have held allegorical meaning for their creator.