Discord of Melkor

"Mighty are the Ainur, and mightiest among them is Melkor; but that he may know, and all the Ainur, that I am Ilúvatar, those things that ye have sung, I will show them forth, that ye may see what ye have done. And thou, Melkor, shalt see that no theme may be played that hath not its uttermost source in me, nor can any alter the music in my despite. For he that attempteth this shall prove but mine instrument in the devising of things more wonderful, which he himself hath not imagined."

- Ilúvatar despising Melkor's music.

The Discord of Melkor was a disruption of the Music of the Ainur which would foretell what would be brought upon the world (Arda) as a result.

The First Theme
After Ilúvatar told the Ainur about a great music coming, they played the Music of the Ainur, which would signify the world's creation, their voices like the sound of harps, trumpets, and choirs. However, Melkor desired to “increase the power and glory of the part assigned to himself”, so he, too, puts it into song, thus creating the Discord, as his thoughts were very different from that of his fellow Ainur. His song caused the Discord to turn the Music from a “sea of turbulent sound” into a “raging storm” of sound. During this time period, Eru rose from his seat and rose his left hand. Thus, a new theme took place.

The Second Theme
The Second Theme was made as “like and yet unlike” the First, as it gathered new power and beauty. However, Melkor was able to make his discord triumph over it, causing a “war of sound more violent than before”, as many of the Ainur stopped singing out of dismay. Then, Eru rose his right hand, and a new theme began.

The Third Theme
The Third Theme was unlike the first two themes. It slowly rose up from the Scond Theme's confusion, and sounded like the rippling of soft notes. However, Melkor struck one again. Therefore, there were two themes playing. One theme was full of “immeasurable sorrow” which gave it great beauty, while the other theme, played by Melkor, merely took the former theme's notes and “[wove them] into its own solemn pattern”. This clash between two themes caused Ilúvatar's dwelling and even the Void to shake. Finally, he had a terrible face, and rose once more with both of his hands up high, “and in one chord, deeper than the Abyss, higher than the firmament… the Music ceased.”