One of the problems on the web is that anyone can set themselves up as an authority and purport to produce "historical" arguments without any sense of the status of evidence and methods of demonstration. A recent example is http://paul-barford.blogspot.com/2011/09/stitching-up-sforzas.html.
Barford cobbles together bits from some press discussions, which he then uses as the basis of a series of arbitrary assertions. He has not looked at the full evidence available on the website of the Leonardo da Vinci Society or on the Lumiere Technology website. Codicology (the study of the compilation of codices) is something that needs to be thought through very systematically. The web, and, indeed all electronic means of communication, exhibit a tendency to foster ill-researched polemics that masquerade as objective reviewing of evidence. I have submitted a comment, which is subject to Barford's editing. It will be interesting to see if he posts it.