The effect of the Great Rings upon Men

[Inziladun]

Originally Posted by Mithadan

However, death is the Gift of Eru to Men. Their feär seek beyond the boundaries of Arda. I recall from somewhere that the Gift could not be withheld even by the Valar. Yet the Great Rings seem to do so. Your thoughts?

I recall that quote, too. Yet, we see Morgoth exerting power on Húrin when the latter is captured and imprisoned.
Húrin was placed atop Thangorodrim and, according to Unfinished Tales at least, was not allowed to move or die, until Morgoth chose to release him. I guess it might be argued that Morgoth was just bluffing there, but it does seem that Húrin's biological processes were arrested at that time, as he could hardly eat, drink, or, ahem, perform other organic functions while "bound" by Morgoth's power.

I think it could have been in the power of certain divine spirits to affect the longevity of mortals in that way, at least temporarily. I would think though that there would have to be a point that the fea of the victim would be so weakened and stretched as to be forced to depart, apart from the body's condition.