Silmarillion to The Legend of Sigurd and Gudrún, which are mostly Christopher Tolkien compiling, editing, and sometimes annotating his father's unpublished stories and publishing them in his father's name.
The History of the Lord of the Rings is a different kind of endeavor, Christopher has pounded through the old man's original manuscripts for LotR, mostly written by hand, on loose leaf paper in both pen and pencil, and has edited and published them as a peek behind the creative curtain. The first volume in this series (there are 4 volumes in all) traces J.R.R. Tolkien's efforts to write the sequel to The Hobbit. The material covered in this first volume, The Return of the Shadow, would eventually become The Fellowship of the Ring.
Just how to best edit and publish material like this must be a nightmare. As one can imagine, the manuscripts pages are wrinkled, ripped and faded, out of order and often not numbered, and the writing is often edited by J.R.R. Tolkien immediately, in the act of writing, or somewhat later. Multiple times. There are examples of scanned sheets showing text struck through, and inserted; there are scribbles of ideas, things to check, marginal notes, and translations in elvish or dwarvish, as the case may be. Some pages are interrupted by illustrations or maps; and he also apparently would change his mind mid-sentence, and begin again without striking out the previous text at all. The entire story was begun multiple times, with different characters, time periods, and intentions. How Christopher Tolkien made sense of it, and was able to bring it to a printed version at all is beyond me.
I was not particularly surprised to see that much of the original drafts of the story haven't changed much, but there are elements of the story that are dramatically different in their final form than what Tolkien originally conceived. What was surprising is that Tolkien had no idea what his sequel was to be about, yet he started in writing just the same, roughing out chapter after chapter, often in fits and starts, building characters and scenes that end up (in one form or another) in the final story without knowing anything further than the next line. It was stunning to learn that whole conversations were kept and simply given to new characters as the story developed.
Reading the first part of this book a number of years ago actually inspired me to pick up an old story of mine and start writing again. I had been stuck in the narrative, not knowing what was next, or how my story might end. After reading that one of the finest modern myths was written without knowing these things, I actually put this book down without finishing it so I could spend my time writing.
When I picked this book up a week or so ago, my bookmarker was still in there, so I finished it. I've got the other three volumes on the shelf, and I understand that there are further volumes similar to this in the larger, 12 volume collection know as The History of Middle Earth, of which The History of the Lord of the Rings are volumes 6 through 9.