The Silmarillion, now published four years after the death of its author, is an account of the Elder Days, or the First Age of the World. In The Lord of the Rings were narrated the great events at the end of the Third Age; but the tales of The Silmarillion are legends deriving from a much deeper past, when Morgoth, the first Dark Lord, dwelt in Middle-earth, and the High Elves made war upon him for the recovery of the Silmarils.
There was Eru, the One, who in Arda is called Ilúvatar; and he made first the Ainur, the Holy Ones, that were the offspring of his thought, and they were with him before aught else was made. And he spoke to them, propounding to them themes of music; and they sang before him, and he was glad. But for a long while they sang only each alone, or but few together, while the rest hearkened; for each comprehended only that part of me mind of Ilúvatar from which he came, and in the understanding of their brethren they grew but slowly. Yet ever as they listened they came to deeper understanding, and increased in unison and harmony
And it came to pass that Ilúvatar called together all the Ainur and declared to them a mighty theme, unfolding to them things greater and more wonderful than he had yet revealed; and the glory of its beginning and the splendour of its end amazed the Ainur, so that they bowed before Ilúvatar and were silent.