What were the different themes in the Great Music of the Ainur?

Question

The LotR Wikia page on Melkor tells us:

When the Ainur sang the Great Music before Eru, Melkor wove some of these alien thoughts into his music, and straightaway Discord arose around him. Some of those nearby attuned their music to his, until two musical themes were warring before the Throne. To correct the Discord, Eru introduced a Second, and then a Third Theme into the music.

Other than what we can induce from the historical events of Arda themselves, what do we know about the themes within the Great Music? There were four distinct themes:

1. Eru's original theme
2. Melkor's theme
3. Eru's second theme (with Manwe as the "chief instrument")
4. Eru's third theme - the theme of Elves and Men

Specifically, to what extent are the additional themes "just patches", e.g. "Ok, I'll also throw in the Elves and Men"?

Answer 1

There were many themes of music before the First Theme:

There was Eru, the One, who in Arda is called Iluvatar; 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;

After a timeless time, Iluvatar called them all together to sing a First Theme which was his alone:

And it came to pass that Iluvatar 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 Iluvatar and were silent.

Then Iluvatar said to them 'Of the theme that I have declared to you, I will now that ye make in harmony together a Great Music. And since I have kindled you with the Flame Imperishable, ye shall show forth your powers in adorning this theme, each with his own thoughts and devices, if he will. But I win sit and hearken, and be glad that through you great beauty has been wakened into song.'

Melkor couldn't tolerate being second fiddle, and

...as the theme progressed, it came into the heart of Melkor to interweave matters of his own imagining that were not in accord with the theme of Iluvatar, for he sought therein to increase the power and glory of the part assigned to himself...

Then the discord of Melkor spread ever wider, and the melodies which had been heard before foundered in a sea of turbulent sound. But Iluvatar sat and hearkened until it seemed that about his throne there was a raging storm, as of dark waters that made war one upon another in an endless wrath that would not be assuaged.

Iluvatar reacted:

Then Iluvatar arose, and the Ainur perceived that he smiled; and he lifted up his left hand, and a new theme began amid the storm, like and yet unlike to the former theme, and it gathered power and had new beauty. But the discord of Melkor rose in uproar and contended with it, and again there was a war of sound more violent than before, until many of the Ainur were dismayed and sang no longer, and Melkor had the mastery.

This Second Theme featured Manwe:

...Manwe was the brother of Melkor in the mind of Iluvatar, and he was the chief instrument of the second theme that Iluvatar had raised up against the discord of Melkor;

But Manwe did not prevail and:

Then again Iluvatar arose, and the Ainur perceived that his countenance was stern; and he lifted up his right hand, and behold! a third theme grew amid the confusion, and it was unlike the others. For it seemed at first soft and sweet, a mere rippling of gentle sounds in delicate melodies; but it could not be quenched, and it took to itself power and profundity. And it seemed at last that there were two musics progressing at one time before the seat of Iluvatar, and they were utterly at variance. The one was deep and wide and beautiful, but slow and blended with an immeasurable sorrow, from which its beauty chiefly came.

This Third Theme (explicitly so named) introduced Elves and Men:

For the Children of Iluvatar were conceived by him alone; and they came with the third theme, and were not in the theme which Iluvatar propounded at the beginning, and none of the Ainur had part in their making....

Now the Children of Iluvatar are Elves and Men, the Firstborn and the Followers.

[emphasis added]

But that's not the end,

...it has been said that a greater still shall be made before Iluvatar by the choirs of the Ainur and the Children of Iluvatar after the end of days. Then the themes of Iluvatar shall be played aright, and take Being in the moment of their utterance, for all shall then understand fully his intent in their part, and each shall know the comprehension of each, and Iluvatar shall give to their thoughts the secret fire, being well pleased.

So, in summary:

• Many individual themes
• The First Theme of Iluvatar
• Melkor's discords
• Iluvatar's Second Theme (Manwe)
• Melkor's discords continue
• Iluvatar's Third Theme (The Children of Iluvatar)
• The Music after the end of Arda

Answer 2

I believe the last two themes were the Elves and the Men

Tolkien discusses The Music of the Ainur in Letter 212.

He begins by describing what you refer to as the first theme the Design propounded to them by the One.

The Ainur took part in the making of the world as 'sub-creators': in various degrees, after this fashion. They interpreted according to their powers, and completed in detail, the Design propounded to them by the One. This was propounded first in musical or abstract form, and then in an 'historical vision'. In the first interpretation, the vast Music of the Ainur. This was propounded first in musical or abstract form, and then in an 'historical vision'.

_{The Letters of JRR Tolkien: Letter 212}

Ho goes on to refer to what you call the second theme as alterations made by Melkor.

In the first interpretation, the vast Music of the Ainur, Melkor introduced alterations, not interpretations of the mind of the One, and great discord arose.

_ibid

After describing how the One made the 'historical vision' a reality ("Eä") and how many of the Ainur chose to enter into Eä, Tolkien goes on to discuss Elves and Men.

Elves and Men were called the 'children of God', because they were, so to speak, a private addition to the Design, by the Creator, and one in which the Valar had no part. (Their 'themes' were introduced into the Music by the One, when the discords of Melkor arose.) The Valar knew that they would appear, and the great ones knew when and how (though not precisely), but they knew little of their nature, and their foresight, derived from their pre-knowledge of the Design, was imperfect or failed in the matter of the deeds of the Children.

_ibid

Note how the letter say that their themes (plural) were added by the Creator. I take it from this that what you refer to as the third and fourth themes are the two themes that represent Elves and Men.

Tolkien also referred to the themes (not theme) of Elves and Men in Letter 257.

In O[xford], I wrote a cosmogonical myth, 'The Music of the Amur', defining the relation of The One, the transcendental Creator, to the Valar, the 'Powers', the angelical First-created, and their part in ordering and carrying out the Primeval Design. It was also told how it came about that Eru, the One, made an addition to the Design: introducing the themes of the Eruhîn, the Children of God, The Firstborn (Elves) and the Successors (Men), whom the Valar were forbidden to try and dominate by fear or force.

The Letters of JRR Tolkien: Letter 257

Summary

I believe that in the Letter, Tolkien describes the Music as consisting of:

1. The Design created by the One.
2. Alterations to the Design added by Melkor.
3. The theme of the Elves, created by the One.
4. The theme of Men, created by the One.

Different versions of the mythology

Tolkien worked on the mythology over a period of decades and produced many drafts that differed in both major and minor details.

I believe Mark Olson's excellent answer is based on what Christopher Tolkien refers to as "Version C" of the Ainulindalë, which is printed in Morgoth's Ring (Volume X of The History of Middle-earth). I believe that version was completed by the early 1950s.

My answer is based on letters written by Tolkien in 1956 (Letter 212) and 1964 (Letter 257). I don't point this out to try to argue that the version in Letters is later and so must be "correct", I'm simply explaining why there can be two incompatible answers that both quote Tolkien's writing.

As to which version is correct, Tolkien didn't get around to publishing either version, so we can't know which he would have picked (or he might have written a third version). We are all free to pick the version we prefer.