What posthumously published 1977 book contains Tolkien’s mythology of Arda?

The Silmarillion, published in 1977, contains J.R.R. Tolkien’s broad mythology of Arda.

The book was edited and organized by Tolkien’s son Christopher after Tolkien’s death. It presents stories of the creation of Eä, the shaping of the world, the divine Valar, the Elves, and the great conflicts of the First Age. Its central sections include the Quenta Silmarillion, the account of the First Age wars over the Silmarils.

Unlike The Hobbit and The Lord of the Rings, The Silmarillion is not a single continuous novel with one central narrator. It combines mythic history, annal-like material, genealogies, and narrative tales. Christopher Tolkien assembled the published form from a large and changing body of drafts and notes.

The title can cause confusion with The Book of Lost Tales and The History of Middle-earth, which also contain earlier or related versions of Tolkien’s mythology. The Silmarillion is the name of the 1977 posthumous volume that became the standard gateway to the First Age and the deeper history behind Middle-earth.