An example of what happens when cats keep you company as you work.
The story is not new first posted in April, but it was new to me. There are closeups in the historian's Flickr account. The text is in Croatian, but at first glance, the hand is not so different from other 15th c business hands I've seen. It's in a collection of business letters, rather than a book w/ a single topic.
Since they are in a bound book of letters, rather than on a single page, it suggests to me that the cat was walking across the book when it was open, not the individual page as it was being produced...but perhaps the book was open on a reading desk? was being copied or referenced in a library?