Killing Maia

[Son of Númenor]

Gandalf 'died' on the 25th of January and was brought to Lothlórien by Gwaihir on the 17th of February. Assuming Gandalf was reborn on the day that Gwaihir bore him to Caras Galadhon, his 'reformation' took a grand total of twenty-three days.

But I'm guessing that was more of a rhetorical question, Bêthberry.

Gollem observes "Yes, He has only four on the Black Hand, but they are enough."

Could Sauron not reproduce the finger that was lost? Could he have been eliminated, um, piecemeal?

It can be argued both ways. If "the Black Hand" is a metaphor (exempli gratia "The Yellow Face" & "The White Face"), then the 'four fingers' is also a metaphor - for the literal loss of a finger in his previous incarnation, and for the loss of the Ring. If it is not, then Tolkien is implying that Gollum has come into contact with a physical manifestation of Sauron. The latter seems less likely to me.

Now I will my attempt to answer the question with a few questions of my own (I have been doing it alot lately): How would Gollum have known that Sauron lost a finger to begin with? and why should we trust what that Stinker says anyway?

[Knight of Gondor]

Well, how long did it take Gandalf?

I think there is at least one aspect for which we can find some kind of vague reference.

Gandalf, as I understand it, "reported back" to the Valar, as in "I was sent back". They were the ones who sent him back. Sauron and the Witchking did not "report" to the Valar. And I believe it only took a symbolic three days (try reading the New Testament if you don't know what it's symbolic of, ) for Gandalf to return in physical form, albeit clothesless. He just had to be hefted to Lorien where he could get him some clothes. (You stop imagining Gandalf in Lorien without clothes! That's an order!)

[Guinevere]

In letter #246 Tolkien wrote about Sauron's bodily form in the time of the War of the Ring:

Sauron should be thought of as very terrible. The form that he took was that of a man of more than human stature, but not gigantic. In his earlier incarnation he was able to veil his power (as Gandalf did) and could appear as a commanding figure of great strength of body and supremely royal demeanour and countenance.

I think Gollum really did see him. (one of the few proofs that Sauron wasn't just an eyeball . Why should he make up this detail about the missing finger? And I don't think he would use this as a metapher.

In this quote from letter #200, Tolkien writes explicitly about Sauron's taking shape.

I note your remarks about Sauron. He was always de-bodied when vanquished. The theory (...) is that he was a spirit, a minor one, but still an "angelic" spirit. According to the mythology of these things that means that, though of course a creature, he belonged to the race of intelligent beings that were made before the physical world and were permitted to assist in their measure in the making of it. Those who became most involved in this work of Art, as it was in the first instance, became so engrossed with it, that when the Creator made it real (...) they desired to enter into it, from the beginning of its "realization".
They were allowed to do so, and the great among them became the equivalent of the "gods" of traditional mythologies; but a condition was that they would remain "in it" until the Story was finished. They were thus in the world, but not of a kind whose essential nature is to be physically incarnate. They were self-incarnated, if they wished; but their incarnate forms were more analogous to our clothes than to our bodies, except that they were more than are clothes the expression of their desires, moods, wills and functions. (.....) It was because of this preoccupation with the Children of God that the spirits so often took the form and likeness of the Children, especially after their appearance.

It was thus that Sauron appeared in this shape. It is mythologically supposed that when this shape was "real" (that is a physical actuality in the world and not a vision) it took some time to build up. It was then destructible like other physical organisms. But that of course did not destroy the spirit, nor dismiss it from the wolrd to which it was bound until the end.
After the battle with Gil-Galad and Elendil, Sauron took a long while to re-build, longer than he had done after the Downfall of Númenor. (I suppose because each building-up used some of the inherent energy of the spirit, which might be called the "will" or the effetive link between the indestructible mind and being and the realization of its imagination.)
The impossibility of re-building after the destruction of the Ring, is sufficiently clear "mythologically" in the present book.

[Knight of Gondor]

But I'm curious as to how many times he can be killed? It's like he has constantly renewable forms he can take, but there comes a point when he can no longer assume a fair form, such as after Numenor. If that's so, how did the Ring's demise cause him to lose form? I know much of his power was in it (some say his very blood) but why does this cause him to fade beyond reckoning? Where did his spirit go? Do mortals have the power to thrust Maia into the Void?

[Son of Númenor]

But I'm curious as to how many times he can be killed?

As I said, there is no set amount.

It's like he has constantly renewable forms he can take, but there comes a point when he can no longer assume a fair form, such as after Numenor.

The only explanation is that the number of times he could assume another form before being unable to take a 'fair form' is subject to the whim of Eru.

If that's so, how did the Ring's demise cause him to lose form?

The Ring was tied to him. When the Ring was destroyed, he lost the power to have a physical form or a 'potent spirit' (to misquote the movies) within Middle-earth.

Where did his spirit go?

What remained of Sauron's 'spirit' went into the Void with Morgoth. The part that was destroyed with the Ring was, um, destroyed.

Do mortals have the power to thrust Maia into the Void?

No.

I hope that helps.

[Sharkû]

Gandalf returned because he was sent back by an order higher than his own power to reincarnate and higher than the Valar; he wandered 'beyond space and time', after all.
Sauron lost his ability to assume new forms, including after the destruction of a current one, when he fully incarnated himself to forge the Ring. Before that he was just fine, albeit perhaps diminished in power to an unknown degree.

[Lalaith]

What about Balrogs? They were Maia too...did they come back after being dispatched (by Gandalf, or by Glorfindel at Gondolin etc)
And as for mortals not killing Maia, wasn't Saruman (Maia) killed by Wormtongue (mortal man)?