Also called 'the Great Music' and the Ainulindalë.

When Ilúvatar created the Ainur, he showed them how to create music, and they sang before him - each on their own. Eventually, as they sang, their understanding of music and all the other Ainur increased, and when that happened, Ilúvatar called them all together. He told them to create a Great Music together, using each of their own talents and powers to add to the theme.

The voices of the Ainur were like harps and lutes, pipes and trumpets, viols and organs, as well as the voices of countless choirs, and together they created a melody of endless interchanging melodies woven in harmony. The Music flowed out from the dwelling of Ilúvatar into the Void, and the Void was filled for the first time.

As the theme progressed, Melkor decided that he would weave matters of his own imagination into the harmony - matters that were not in line with the theme of Ilúvatar. These thoughts were designed only to give Melkor more power and glory within the Music. Melkor's thoughts caused discord in the Music, and those Ainur nearest to him faltered in their tunes. Some adjusted their own melodies to that of Melkor until the whole melody unravelled and was in discord.

Ilúvatar then rose, lifted his left hand, and began a new theme amidst the storm. But again the discord of Melkor rose up against it until the sound was more brash and violent than before. Many of the Ainur were dismayed and sang no longer, giving Melkor mastery over the Music.

Ilúvatar rose again, lifted his right hand, and brought forth yet another theme. This one was soft, a small rippling of gentle music, but it could not be subdued by Melkor, and it grew in power until it was as strong as the music of Melkor. The two musics were utterly different - Melkor's was loud, brash and endlessly repeated; while that of Ilúvatar was deep, beautiful, slow and composed of sorrow.

The two Musics competed against each other until Ilúvatar rose again, raised up both hands, and in one chord - infinitely deep, high and piercing - the Music ceased.

Ilúvatar then showed the Ainur what they had created with their music - Arda, and everything in it. However, the Children of Ilúvatar, who were created by him alone, came to fruition only in the third theme.

The vision of Arda was only a foreshadowing of what was to come now that Time had begun. When Ilúvatar actually created the world, the Ainur then realised that they had to achieve the results of what they had sung, and many of them went down to Arda to shape the world.
Encyclopedia entry originally written by atalante_star