This article is from the Tolkien Newsgroups FAQ, by Steuard Jensen sbjensen@midway.uchicago.edu with numerous contributions by others.
[This updates question V.D.1 of the Tolkien LessFAQ.]
A great deal of information on this topic can be found in _Morgoth's
Ring_ (HoMe X). Tolkien's latest thoughts on the issue can be found in
"Note 3" to the "Athrabeth Finrod ah Andreth" and in the Appendix to
that text. In brief, when Elves died, they were summoned to Mandos.
Once the Valar deemed them to be ready, they could (if they wished) be
directly re-embodied (with the aid of the Valar) in a body identical to
the one they had lost. Tolkien clearly abandoned the idea that the
Elves could be re-born as children.
"Note 3" says that Elven spirits "could refuse the summons [to
Mandos], but this would imply that they were in some way tainted".
Details of such refusals are not given in the text above, but are
discussed in an earlier essay: "Laws and Customs among the Eldar", part
of "The Later Quenta Silmarillion (II)" in _Morgoth's Ring_. Those who
refused "then had little power to resist the counter-summons of
Morgoth." The reason for this "counter-summons" is not explained, nor
is it clear what became of them after Morgoth's defeat, but the text
mentions that some of the living sought to speak with the "Unbodied" or
even to control them, and that "Such practices are of Morgoth; and the
necromancers are of the host of Sauron his servant."
 
Continue to: