The Ainulindalë sets out a central part of the cosmology of Tolkien's legendarium, telling how the Ainur, a class of angelic beings, perform a great music prefiguring the creation of the material universe, Eä, including Middle-Earth.
The creator Eru Ilúvatar introduces the theme of the sentient races of Elves and Men, not anticipated by the Ainur, and gives physical being to the prefigured universe.
That large body of stories was edited after his death by his son Christopher, initially in 1977 as a single text, The Silmarillion, containing a version of the Ainulindalë.
[T 2] That was followed, between 1983 and 1996, by the twelve volumes of The History of Middle-earth, which revealed and annotated the many drafts of the overlapping stories of the legendarium, including other versions of the Ainulindalë.
Although his "loud, and vain" music disrupts the harmony, Ilúvatar stands, smiles and raises his left hand to begin a new theme.
Despite Melkor's efforts, Ulmo's water cannot be ruined by heat or cold; he and Manwë are revealed as the primary agents of Ilúvatar's plans.
When the Valar later assume bodily form, the first war of Eä begins, but Manwë's efforts make the Earth habitable for Elves and Men.
[T 4] The first draft of the story, written in pencil, does not vary significantly from the published version; future changes involved the addition of Manwë and Aulë.
[T 9][T 10] In 1948 Tolkien began a new version, eliminating mentions of the Sun and the Moon, and introducing the concept that Ilúvatar created the world after the visions of the Ainur died away.
[8] Despite the story's Norse pagan elements, such as the Ainur performing the creative work of Ilúvatar, other aspects of the Ainulindalë reflect Tolkien's Catholicism.
[9] His pre-Christian story[9] has been called "Tolkien's Genesis essay";[10] according to another source, "The Biblical parallels evinced by the creation account of the Ainulindalë ... are inescapable.
Joseph Pearce, a Roman Catholic commentator, called it "the most important part of The Silmarillion" and said, "The myth of creation is perhaps the most significant and most beautiful of Tolkien's works.
"[16] According to Fantasy Literature: A Core Collection and Reference Guide, "Every part of [The Silmarillion] benefits from the power and audacity of imaginative genius Tolkien and his brilliant style" and the Ainulindalë has "organ tones".
[18] Although Ralph C. Wood called it "one of the finest and most original of [Tolkien's] writings",[13] the stylistic differences between this story and the rest of The Silmarillion have been the subject of debate.