The History of Middle-earth volume 1

The Book of Lost Tales stands at the beginning of the entire conception of Middle-earth and Valinor, for the Tales were the first form of the myths and legends that came to be called The Silmarillion. Embedded in Endlish legend and English association, they are set in the narrative frame of a great westward voyage over the Ocean by a mariner named Eriol (or Elfwine) to Tol Eressёa, the Lonely Isle, where Elves dwelt; from them he learned their true histiry, the Lost Tales of Elfinasse. In the Tales are found the earliest account and original ideas of Gods and Elves, Dwarves, Balrogs and Orcs; of the Silmarils and the Two Trees of Valinor, of Nargothrond and Gondolin; of the geography and cosmology of the invented world.