Sketch of the Mythology
Origionally written as an outline to explain the background to the alliterative 'Children of Hurin' to Tolkien's old tutor and friend R.W. Reynolds, it later became the basis from which all work on the Legendarium derived.
While only 28 pages long, the narrative in the Sketch advances a great deal from The Book of Lost Tales, approaching the final form in most respects, albeit extremely condensed. It was superseded by the Quenta Noldorinwa in 1930.