I think that sometimes disorder is merely a new order, to a different purpose. Of course, sometimes it
is just disorder.
Older manuscripts not rarely show signs of deliberate re-ordering in which case that re-ordering, and the reason for it, is potentially an informative historical datum, one which would be lost or forgotten were the ordering 'corrected' to what we imagine the 'proper' order.
The quiration also speaks to assembly of the parts from one or more sources that had not formed a nicely ordered single volume.
I find Sam's observations very interesting indeed in that context, and can think of numerous situations where separate bifolia would be practical.
One, of course, would be the printer's workshop. Another would be, say, a chart-maker's workshop, or the needs of a painter working on a great fresco. In each case, as one section and then other were being worked on, only the small sheet (bifolium) relating to it would be needed.
A slightly different possibility might be that the new ordering (i.e. as bound in the 15thC) reflects the sequential order of a journey, with information about roads (chiefly maritime, I'd say) and other matter taken from one or more prior sources being organised according to the user's journey-stages. I don't imagine what we have is a travel diary by one author, but a compilation made to a purpose.
However, from my point of view, the chief problems posed by the "roots and leaves" sections are first, that the layout is quite contrary to the habit of Latin Europeans during the fourteenth and fifteenth centuries, and second that the concertina-fold itself is so highly unusual for such posited context.
The nearest I've seen to the horizontal layout among Latin European works are a couple of mercantile invoices and lists which write the item within a separate paragraph, and then illustrate it in the same register, directly to the left and/or right in the margin. But that still isn't exactly the layout of the 'roots and leaves' section. And I've never seen a concertina-fold invoice. What I did find were comparable practices in a region east of Europe.
That aside: if we just try to understand why the manuscript is formed
as it is - and of course why the imagery is formed as it is too - then I think the chances are better that we will make a real break-through with the written part of this text. To distinguish between understanding something, and rationalizing it, isn't always easy, and to slide from one to the other is a constant temptation - the worse for being unconscious.
It is terribly easy to hide from ourselves our own bewilderment by projecting some character-flaw or irrationality onto what eludes our understanding. No-one likes to feel stupid, especially not people used to being the brightest kids in the school - like us.
But it's a universal tendency - it's the same mechanism that leads people to suppose that "foreigners" are less rational and reasonable than their own countrymen, when actually the problem is ignorance of the reason for other ways. In this case, MS Beinecke 408 is the "foreigner", whose home is in the other country of the past, where things are done differently. Though, in this case, rather more differently than most.
- as I see it.