10% of Medieval Manuscripts survive to this day - Is that an overestimate?

[Mark Knowles]

In the case of early 15th century ciphers from my research I would be inclined to the view that much fewer than 10% of enciphered letters survives. I suspect the percentage is higher when it comes to cipher ledgers, though I doubt it is as much as 10%.
However when we are talking about illustrated manuscripts then I would think they are more likely to have survived than in the case of letters, especially if they are very beautiful manuscripts as I would expect people to have taken more care of them.
Having recently having allowed myself to be distracted by the subject of Diebold Lauber's manuscripts I have wondered which of these manuscripts survive and having seen the following listing:

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I wonder how many manuscripts in total Diebold Lauber's workshop would have produced and what percentage of that figure this listing constitutes. Of course, there may well be a number of surviving Diebold Lauber manuscripts not listed here.

[bi3mw]

Whether it is 10% or less, the fact is that a large part of our idea of the Middle Ages is based to a not inconsiderable extent on what we have in written tradition. Unfortunately, this is really only a small fragment. After all, people today have more extensive access to manuscripts than people in the Middle Ages ever had.

[Scarecrow]

The chances of old manuscripts surviving, depended on many things, mostly on their type and their subject matter, but also where it was made. Religious and liturgical texts have the highest rates of preservation, owing to their sacred significance and the deliberate care taken to protect them. In contrast, secular writings, personal documents, and practical manuals tend to have much lower survival rates. 

It is estimated that scientific manuscripts like herbals, medicine, and other natural sciences, but also alchemy, had a moderate chance of surviving. They were valuable for learning and passed around among scholars and healers. Their survival rate is better than letters, manuals and stories.but less than religious matter.

So while 10% is general estimate, class survival rates can differ quite a bit.

[Koen G]

I'd assume that being lavishly illustrated would also increase a manuscript's chances of survival. It's like a bunch of pocket paintings.

[Scarecrow]

I'd assume that being lavishly illustrated would also increase a manuscript's chances of survival. It's like a bunch of pocket paintings.

Surely the survival of the manuscript also depended on how valuable the owner considered it and how important it was perceived to be.
Manuscripts that were richly illuminated, decorated, or beautifully written were usually more carefully preserved because they were seen as valuable works of art, not just texts. This especially during renaissance period, but depended heavily on the location of the manuscript/owned.

[ReneZ]

War zones, fires and careless storage are probably among the greatest causes of loss.
These are to some extent dependent on the region.

In fact, the Voynich MS came quite close to being burnt in 1849.

Edit:
here is a You are not allowed to view links. Register or Login to view. with a link to more information about it.

[Scarecrow]

As Lisa says in that post, VMS is a heroic and surprising survivor, as it defies the logic of social-, artistic- and scientific value, at least.
Was the survival of our hero planned and intentional - choosing parchment, building a network of sponsors, owners and supporters through the history, or just a coincidence.

[ReneZ]

Unless there were 9 more of them...

[Scarecrow]

.. or if it was one of the other 9 books from the same author(s), part of a 10 book encyclopedia

[Mark Knowles]

The fact that the Voynich manuscript is an unusual manuscripts probably help a bit it its survival as their were clearly people throughout history who were interested in it, because of its distinctive quality. However, there were most probably other unusual medieval manuscripts that have not survived.