[Roa_Aoife]

An interesting question, to be sure. I'd have to say there's a yes and no answer. Melkor, from the beginning, was the cause of the discord, and hence the evil in creation. It wasn't necessary for him to enter it for evil to exist, but then again, it WAS necessary for him to enter. Recall that Men are distinguished from both the Elves and the Valar and Maiar in that Men are not bound by fate. Melkor, as one of the Ainur, was bound. From the moment he began the discord, his fate was sealed. One could say his role as the embodiment of evil was inevitable.

Had Melkor himself not entered, one of the lesser Ainur, the Maiar, would have taken the role, or perhaps one of the Valar that did enter. Melkor wasn't the only one involved in the discord, after all. As I said, the only people in Middle Earth NOT tied to this destiny were Men, because they had the ability to choose their own fate. Unfortunately, they were also the easiest to corrupt, perhaps because of that very reason.

Groin, remember that Morgoth was in a whole other league from Sauron. The only ones who could defeat him were the Valar themselves, with all of the peoples of Middle Earth helping. Sauron, on the other hand, could be defeated without the help of the Valar, as was shown at the great battle just as the second age ended and the third age began. The Valar did send help though, in the form of the Istari- the five wizards. Their original job was to stand against and defeat Sauron, though all but Gandalf wandered away from that goal. And Frodo cried out to the Valar when he was in need and felt as though he was helped. Gandalf lets him know that he is never alone, and it is implied that unseen forces are at work through out.