Why did Frodo feel he had to leave Middle Earth at the of ROTK?

[Inziladun]

Originally Posted by Lotrelf

Does only the land matter? Trees were killed/destroyed. There was darkness all around, if I remember that correctly. It's like saying poisonous air is not in the land so those who live on the land do not need to fear it, while the birds etc. are in greater danger. It 's a bad analogy, but for now I can't think of something better!

The darkness wasn't permanent, though. It left no lasting damage in the Blessed Realm. I also like radagastly's take, which seems in a more ethereal sense along the lines of where I was aiming.

[Zigûr]

Do we have a precise timeframe on when Morgoth started actively trying to turn matter to his will, leeching his essence into the world, as it were? It was clearly after the destruction of the Lamps, because otherwise Aman would presumably have been tainted. Melkor was weakened by the time he was captured in the Battle of the Powers, but that was seemingly, mostly, from putting his essence into his agents, particularly his Maiar servants and his experiments. Did he only start actually imbuing Arda with his spirit after returning to Middle-earth with the Silmarils, or had he already been doing it beforehand? Morgoth's Ring observes that "It is quite possible, of course, that certain 'elements' or conditions of matter had attracted Morgoth's special attention (mainly, unless in the remote past, for reasons of his own plans)." Perhaps this project was begun before Utumno was destroyed but only reached full operation when he was enthroned in Angband.

[Inziladun]

Originally Posted by Zigûr

Do we have a precise timeframe on when Morgoth started actively trying to turn matter to his will, leeching his essence into the world, as it were? It was clearly after the destruction of the Lamps, because otherwise Aman would presumably have been tainted. Melkor was weakened by the time he was captured in the Battle of the Powers, but that was seemingly, mostly, from putting his essence into his agents, particularly his Maiar servants and his experiments. Did he only start actually imbuing Arda with his spirit after returning to Middle-earth with the Silmarils, or had he already been doing it beforehand?

The question of Melkor's "essence" becoming part of those Maiar he had seduced is a good one. However, it would appear that any servants or followers of Melkor had been purged from Aman by one means or another. They had either been "destroyed" like Gothmog and probably many other Balrogs, repented genuinely (perhaps, though the reader is given no such example), or had run to Middle-earth to hide from the Valar (like Sauron and the Moria Balrog).
With none of Melkor's corrupted slaves or followers present, Aman had no lasting effect of evil, and could be said to be "unmarred" in comparison with the outer lands.

[Lotrelf]

Originally Posted by Inziladun

The darkness wasn't permanent, though. It left no lasting damage in the Blessed Realm.

One final question- What about the Trees, did they ever recover? If not, how can the effects of Morgoth's darkness be said temporary?

Another question just popped in: In The Silmarillion, at one point, Professor says that whenever Elves were to give any message or something by Valar they were given dreams or visions. In LotR, Frodo often sees visions or dreams. His Elvish nature is also the reason he leaves for the Undying Lands. Is there any connection?

[Zigûr]

Originally Posted by Lotrelf

One final question- What about the Trees, did they ever recover? If not, how can the effects of Morgoth's darkness be said temporary?

The Trees never recovered. After Yavanna retrieved the fruit and flower which would become the Sun and Moon, "then the Trees died, and their lifeless stems stand yet in Valinor, a memorial of vanished joy."

The reason we don't consider Aman to be Marred like the rest of Arda is because unlike the rest of Arda the matter of Aman is not combined with Morgoth's spirit, something he did in Middle-earth. So the Trees were destroyed, but they and the land at large were not actually corrupted.

[Lotrelf]

Originally Posted by Zig�0‹4r

The reason we don't consider Aman to be Marred like the rest of Arda is because unlike the rest of Arda the matter of Aman is not combined with Morgoth's spirit, something he did in Middle-earth.

Would you please elaborate explaining this?

So the Trees were destroyed, but they and the land at large were not actually corrupted.

Is it also because the Fruits of the Trees covered the entire Arda with their light- night and day, and even Morgoth feared them.?