The Silmarillion:Ainulindalë

[Maedhros]

1. Why was Melkor (being the most powerful of the Ainur), the one who most wanted to do things by his own thought?

But 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 Ilúvatar, for he sought therein to increase the power and glory of the part assigned to himself. To Melkor among the Ainur had been given the greatest gifts of power and knowledge, and he had a share in all the gifts of his brethren. He had gone often alone into the void places seeking the Imperishable Flame; for desire grew hot within him to bring into Being things of his own

Is it a reality in the Silmarillion that the most powerful beings are flawed in a way that they tend to curve to evil?
2. Is the Universe Predefined?

Then Ilúvatar spoke, and he said: '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.'

3. Is Melkor's shame but the beginning of his downfall? Is this the beginning of the element of Pride?
4. Where the Children of Ilúvatar a response to the discord of Melkor? Or was it just the fact that Ilúvatar wanted to made other beings in accord to what he knew best?

In the midst of this strife, whereat the halls of Ilúvatar shook and a tremor ran out into the silences yet unmoved, Ilúvatar arose a third time, and his face was terrible to behold. Then he raised up both his hands, and in one chord, deeper than the Abyss, higher than the Firmament, piercing as the light of the eye of Ilúvatar, the Music ceased.

5. What made some Ainur more entralled to the idea of going to Arda and so to join themselves with the fate of the world?

And they saw with amazement the coming of the Children of Ilúvatar, and the habitation that was prepared for them; and they perceived that they themselves in the labour of their music had been busy with the preparation of this dwelling, and yet knew not that it had any purpose beyond its own beauty. For the Children of Ilúvatar were conceived by him alone; and they came with the third theme,

6. Why was Ulmo the one most instructed by Music by Ilúvatar? Does this has in fact something to do with the way he acts as the story goes on?
7. Is this but a presage to all of us that Arda remade is going to be better than Arda Unmarred?

And Ilúvatar spoke to Ulmo, and said: 'Seest thou not how here in this little realm in the Deeps of Time Melkor hath made war upon thy province? He hath bethought him of bitter cold immoderate, and yet hath not destroyed the beauty of thy fountains, nor of my clear pools. Behold the snow, and the cunning work of frost! Melkor hath devised heats and fire without restraint, and hath not dried up thy desire nor utterly quelled the music of the sea. Behold rather the height and glory of the clouds, and the everchanging mists; and listen to the fall of rain upon the Earth! And in these clouds thou art drawn nearer to Manwë, thy friend, whom thou lovest.'

8. Is it better to stay with Ilúvatar or go to Arda?

Thus it came to pass that of the Ainur some abode still with Ilúvatar beyond the confines of the World; but others, and among them many of the greatest and most fair, took the leave of Ilúvatar and descended into it. But this condition Ilúvatar made, or it is the necessity of their love, that their power should thenceforward be contained and bounded in the World, to be within it for ever, until it is complete, so that they are its life and it is theirs.

9. Melkor becomes a Rebel. Is there any correlation to the way the Silmarillion threats other rebels too?

And there was strife between Melkor and the other Valar; and for that time Melkor withdrew and departed to other regions and did there what he would; but he did not put the desire of the Kingdom of Arda from his heart.