Ilúvatar's other theme.

[Nilpaurion Felagund]

About two weeks after posting this thread, I came upon this line in the Ainulindalë:

Manwë . . . was the chief instrument of the Second Theme that Ilúvatar had raised up against the discord of Melkor.

Ainulindalë

This, understandably, made me bang my head on the wall in shame.

But it seems that my first thought about the separate entrance may have bearing. You see, as a proponent of the special freedom of Men in Arda (not just Death, actual freedom from the Circles of the World, but the virtue to shape their life amid (indeed, in the BoLT version it says 'within' instead of 'amid,' which is more suggesting) the chances of the world beyond even the original Music of the Ainur). It seems to me to fit the make-up of the two Children.

Elves are bound to the World (i.e., Morgoth's Ring), while Men are not. They bring something new to the Theme that overcomes Morgoth's discord.

So, let's say Morgoth's theme is a tank. The Ainur's attempt to contain him is like using a pistol against a tank. It doesn't work.

Second theme (Elves?): Machine gun. The tank staggers back, but realises it's bullet-proof. Continue attack.

Third theme (Men?): Bring out the anti-tank missile. Boom!

I could expound on this, but I'm too busy thinking of Wolves. Sorry.