I see what you mean. I’m still intrigued by the Voynich manuscript, because it doesn’t seem to be “incoherent” writing, like you are talking about with regards to schizophrenics. From appearances, it looks perfectly coherent, just unintelligible to us. Some of the human figure drawings in fact appear to be copies of drawings from other manuscripts of the time. The horticultural drawings are hard to identify, so some claim they are “imaginary” plants, but some of the plants are clearly identifiable, so they can’t all be imaginary. The so-called “astronomic” drawings are probably the least intelligible, but then again, we don’t know that they are astronomic in nature at all. They could be some peculiar alchemical drawings or something of that nature, for all we know.
One interesting thing about the manuscript that few people note, is that not all of the writing in the book is in an unknown alphabet/language. There is a part at the very end of the book that is written in the latin alphabet, though nobody can say if that was added later or by the original author.
I based the incoherant remark on the gist of the story. But, as you are saying there may be a simple answer to this story. Some like to make more of an issue such as this, asking such questions are not helpful.
I noticed the drawings, and I agree with you. They seemed perfectly coherant.
I guess I am just as guilty as the writer of the story, tying to explain in todays experiences. We have no idea what prompted the writings or in fact who wrote them.