structural:expansion
The Silmarillion

Tolkien wrote a brief "Sketch of the Mythology", which included the tales of Beren and Lúthien and of Túrin; and that sketch eventually evolved into the Quenta Silmarillion, an epic history that Tolkien started three times but never published. Tolkien desperately hoped to publish it along with The Lord of the Rings, but publishers (both Allen & Unwin and Collins) declined. Moreover, printing costs were very high in 1950s Britain, requiring The Lord of the Rings to be published in three volumes. The story of this continuous redrafting is told in the posthumous series The History of Middle-earth, edited by Tolkien's son, Christopher Tolkien. From around 1936, Tolkien began to extend this framework to include the tale of The Fall of Númenor, which was inspired by the legend of Atlantis.

Tolkien appointed his son Christopher to be his literary executor, and he (with assistance from Guy Gavriel Kay, later a well-known fantasy author in his own right) organized some of this material into a single coherent volume, published as The Silmarillion in 1977. It received the Locus Award for Best Fantasy novel in 1978.