Leonardo planned to publish many books but only ever co-published one about proportion that he illustrated. This is one of the most intriguing aspects about his written works. There are only around 1/4 that survived and still number in the thousands if not hundreds of thousands of pages. The main translations were taken from those available and then placed into an order that the translator decided upon. Da Vinci did leave behind some notes and brainstorming on the books he intended to write but most of which repeated, changed, and were abandoned. The main reason he censored himself and didn't publish his writings was because of their "Heretical" themes - he could have been punished as Galileo was (He was writing about the same things a hundred years before him!)
Another less practical reason was the sheer amount of content and his erratic way of writing. To go back and try to re-read, re-write, and attempt to organize any of the dozens of books he intended to write would have taken away from him writing new information. At one point he would have realized that the best option would be to give up his intent on publishing and instead leave his notebooks behind for other's to manage. He left most to his assistant Melzi, but after that they were spread around from Country to Country, person to person, collection to collection, and while there have been some attempts to compile them they still refuse to come together in much of a cohesive way. This is because they are more like proto-rough drafts and jumbled and random writings and not a clear cut vision for an actual book. They are doodles, scribbles, random thoughts, and creative ideas from a genius - but complicated mind.
I'll do my best to put them in some kind of order but much of the quotes on similar subjects were written years apart, sometimes new stuff was written on old pages, and sometimes it was as if an idea came to him and he just scribbled on the nearest paper with no notes about when or why it was written. There is a difference between Notebooks, Journals, Books, and creative brainstorming. All of those aspects are present on almost every page of Leonardo's Written works - not to mention the sketches and doodles.
We'll start with his intro's and the books/subjects he intended to write and then get into them themselves. Eventually I would like to be able to include an image of the actual page and translations into various languages. Unfortunately I am not able to understand his writing style, let alone read Italian if I could, and will rely on the English translations. I'll also try and include my own commentary and more modern information relating to his works. -D