[Gordis]

Originally Posted by Farael

However, I think the wraith world is a bit of a misnomer. It is used to explain a perhaps larger concept to people who couldn't understand it otherwise.

The term wraith-word was used only once, IIRC, when Gandalf explained to Frodo the happenings at Weathertop and his interactions with the Ringwraiths. In other places it is called "the Unseen" , "the world of Shadow", "the other side" etc. The latter term I like best, because the Seen and the Unseen worlds are tightly bound together like two sides of the same coin.

Originally Posted by Farael

It wasn't a different reality but just a different perception.

I agree.
The Calaquendi Elves live in both words and wield great power both in Seen and the Unseen. The same likely applies to Maiar.
Ordinary Elves, like Legolas, were able to get some glimpses of the "other side: ‘The Dead are following,’ said Legolas. ‘I see shapes of Men and of horses, and pale banners like shreds of cloud, and spears like winter-thickets on a misty night. "
Even mere Men were able to perceive the Dead at times "Theoden: Folk say that Dead Men out of the Dark Years guard the way and will suffer no living man to come to their hidden halls; but at whiles they may themselves be seen passing out of the door like shadows and down the stony road."

Not so with a Dwarf. The fear fell on Gimli the heaviest, but he saw nothing, only heard whispers. Perhaps it means that the Dwarves have no access whatsoever into the World of Shadow? (Even the 7 Rings were unable to turn them invisible, to transport them into the Shadow-World.)

Originally Posted by Farael

It also explains why the Nazghul didn't see things as the hobbits did. They were almsot solely in the 'wraith' realm and therefore unable to feel with the conventional senses.

They were unable to see in daylight (maybe except the Witch-King), but in the night they were most dangerous:

They themselves do not see the world of light as we do, but our shapes cast shadows in their minds, which only the noon sun destroys; and in the dark they perceive many signs and forms that are hidden from us: then they are most to be feared. And at all times they smell the blood of living things, desiring and hating it. Senses, too, there are other than sight or smell.

Also we know that nazgul have quite acute hearing.
Isn't it interesting that at night the boundary between the two words was not as strictly defined, it seems: the Seen and the Unseen blending?

Going back to the discussion, I think that we are being too hasty claiming the Nazghul had never died. The Witch King was attempting to pierce Frodo's heart with the cursed blade, which would've made him into a wraith instantaneously. If you stop and think about it, piercing someone's heart with anything but a cursed blade of Morgul will also kill them instantaneously. Therefore it may just be that, in order to fully turn a wraith, you have to die physically and your fear has to somehow be 'contaminated' in a way that binds it to Middle Earth rather than going to whatever destiny awaits it (Mandos or the gift of men).

Here I have to disagree. You will not find a single quote referring to Nazgul as "dead" or referring to their deaths.
Then, were the nazgul dead, how could they be killed AGAIN? You can't kill a ghost of Dunharrow - there is nothing to kill - but you can kill a nazgul if you have a right weapon.

Now about the Morgul blade. I doubt it was an ordinary metal weapon, remember it simply melted in daylight. Therefore it is possible that when it pierces a heart, it doesn't damage it enough to cause natural death, instead it delivers a poison (coupled with a dark spell) into the bood flow and changes the characteristics of the victim's body, making it cold and transparent, not needing food, or water, or sleep anymore. It sounds like fanfic, I know, but the nazgul's intention was clearly NOT to kill Frodo. That's why they used the Morgul blade (and were prepared to use another one in Crickhollow as well). The WK had a sword in his other hand and surely it was much easier to skewer the hobbit with it if Frodo had to die first and then to be turned into a wraith.

Originally Posted by Farael

Nazghul are slaves to Sauron and the men of Dunharrow are slaves to their oath.

Nazgul, strictly speaking, are slaves to the Nine Rings which Sauron now holds - therefore to Sauron. But he has lots of other slaves...
I think the real similarity between the Dead and the Undead is that something holds their souls bound to Middle Earth: the Oath and the Rings. In the case of the Houseless Elves it would be their unwillingness to go to Mandos.

So perhaps it's not whether you die or not, but rather whether your soul is free or not at the moment you die.

I would agree with one correction: …at the moment you are expected to die in the case of the nazgul.
The rings prolonged their lives far beyond the normal lifespan. They have become almost what they had desired to become - immortal, like Elves. Only there were 2 drawbacks. 1. Their souls of the Second-born still strived to be free and depart the Circles of the World - thus they felt drained until "every passing moment was a weariness." 2. Their bodies were not supposed to endure so long, but their rings didn't allow them to age and to die normally. Thus the bodies had faded, much like Elven bodies would fade, but much faster and earlier.
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what bound [the Dead] to Middle Earth was their oath and not anything Isildur may have done.

I think so too.

So, since we are making distinctions, I would suggest that there are two different types of "undead" that we read of in LoTR alone.

The wights, which are souls that are trapped in Middle Earth through a curse or an oath or any other entity that has the power to do so and

The spirits of the undead inhabiting bodies or objects.

Nay, I have to propose a different classification:

1.The Undead - with a physical body present, but invisible
1a. Ringwraiths
1b. Wraiths (victims of the Morgul blades)
1c. Faded Elves, the Lingerers.

2. The Ghosts of the Dead - naked fëa without a body -
2a. Men-ghosts (of Dunharrow, Helm's ghost, etc)
2b. Elven ghosts: the Houseless

3. The fëar of the Dead housed in some bodies not their own or in objects.
3a. Houseless Elves "housed" unlawfully in living bodies - "possession"
3b. Houseless Elves (or other naked spirits)"housed" in dead bodies (not their own) - Barrow-wights
3c. Houseless Elves (or other naked spirits) "housed" in stones - Silent Watchers of Minas Morgul and Cirith Ungol