The Book of Lost Tales was J.R.R. Tolkien’s first version of The Silmarillion; which he mostly wrote in the trenches during WWI, almost 100 years ago. The fist 2:30 minutes of this interview, Christopher Tolkien tells the history of The Silmarillion and its connection with The Book of Lost Tales.
This is the first book of a two part book publication that make up J.R.R. Tolkien’s very first Silmarillion, which it was originally called The Book of Lost Tales. As with the final published version of The Silmarillion, this book also uses the same type of old English, archaic, poetic style of writing (that I really love). Also it is worth mentioning that this is the very fist book in the twelve set volume of The History of Middle-earth that I’m planning on reading in its entirety. This book follows the same format as Unfinished Tales of Númenor and Middle-earth, where the story is presented followed by Christopher’s notes and analysis regarding the tale.
I think you first have to read The Silmarillion before you start reading The Book of Lost Tales. As Christopher Tolkien’s literary analysis assumes that you are already familiar with it. I can’t stress enough how thankful we have to be for Christopher Tolkien’s work in editing this book. The Book of Lost Tales was basically is long hard work of gathering his father’s early writings that were made in regular pen/pencil paper notebooks. Almost like an anthropology of his father’s work. It’s truly fascinating reading some half (not yet completed) segments of certain stories of his mythology where J.R.R. Tolkien himself ended erasing the text; up to the point were Christopher wasn’t able to decipher that deleted text.
It’s amazing that practically the overall synopsis of the different stories told in this book are the same as those in the final version of The Silmarillion. They’re are slight differences, for example certain characters have different names, and some of the integrate details of the stories differ to those in the Silmarillion. As Christopher Tolkien mentioned, The Book of Lost Tales mythology was originally meant to stand on it’s own. To me, the most drastic change in the mythology is the different role dwarves had compared to the final version of The Silmarillion.