The tale begins with Ilúvatar's creation of spirits of lesser power than him, yet of independent nature, named the Ainur ("Holy Ones"). Ilúvatar taught them music, and they sang before him, but each one alone. He showed them the most beautiful theme and asked them to sing together a Great Music in which their thoughts would be visible thanks to the Flame Imperishable. Thus began the Music of the Ainur. No music like this was sung again, though it is said that the Ainur will sing a Second Music with the Children of Ilúvatar.
In the beginning of the Music, Ilúvatar sat and hearkened, but Melkor, one of the greatest of the Ainur, in his pride broke the harmony. Ilúvatar then arose and a new theme began against the disturbance, and which Manwë, Melkor's brother, sang the leading part. Yet again, the harmony was broken with Melkor's violent song.
Finally, Ilúvatar began a third theme which the Ainur could not comprehend. He then ceased the music and showed to the Ainur the essence of what their song symbolized, the history of a whole world. This is known as the "Vision of Ilúvatar". The Ainur became fascinated by it, and wished that Ilúvatar put it into being.
Ilúvatar spoke "Eä! Let these things Be!". This command created the universe, and therefore the universe became known as Eä. Some of the Ainur who possessed the greatest power entered into Eä and they were called the Valar, the "Powers of the world", as they their mission was to form the world for the coming of the Children of Ilúvatar. Therefore they created a region which later was called Arda, the Earth, but Melkor attempted to take it for his own. However Manwë asked for the help of other Ainur, great or lesser. They descended to Arda and Melkor was forced to flee to other regions.
The Valar took the shapes of the Children of Ilúvatar, and their beauty and works increased Melkor's envy, so he also took visible form. The First War began in the world, in which Melkor tried to destroy all the works of the Valar, but at last the habitation of the Children of Ilúvatar was established.
The meaning of Ainulindalë (pronounced [ˌaɪnuˈlindale], eye-noo-lin-dahl-eh) is given in the same chapter title: "The Music of the Ainur". It is a Quenya compound: Ainu(r) + lindalë (verb linda- with abstract noun suffix -lë: "music, singing").
 History of composition
- Tolkien rewrote many times the Ainulindalë. To read about each version, see the article Ainulindalë (Rúmil's work).
For his edition of The Silmarillion, Christopher used the last and most complete version, lettered as Ainulindalë D, written in 1951, which was later published in Morgoth's Ring. The text itself was not changed very much, but it was mainly restructured, as Christopher decided to remove the fictional autorship and the narrative frame. In all the versions of the Ainulindalë, it was presented as a work of Rúmil, and in the last versions, Pengoloð the Sage expanded his work narrating the Spring of Arda and describing the main Valar. Removing this frame, Christopher had also to remove all the narrator's words, finishing the tale with the First War, so he moved the second part to the chapter "Of the Beginning of Days".
Christopher also changed some names to make them match with the mature versions, like "habitation set within the vast spaces of the World" is changed from "habitation in the halls of Aman", as Aman was no longer the Elvish name for the World, but Eä (although Christopher didn't use that term in this case).