I can't help but thinking of various passages where Frodo 'feels' an external will telling him to put on the Ring, eg:
Quote:
|
And as he waited, he felt, more urgent that ever before, the command that he should put on the Ring. ("The Stairs of Cirith Ungol", TT)
|
That said, Frodo cannot be fully controlled by this external will, as the passage goes on to say:
Quote:
|
Then his own will stirred; slowly it forced the hand back and set it to find another thing, a thing lying hidden near his breast.
|
In this case, there is a tension between Frodo's will and the command. Frodo is aware of what he wants to do (not put on the ring, for he "knew that the Ring would only betray him") but it takes a while for his will to kick in, and in this time he starts to obey the command ("It took his hand, and as Frodo watched with his mind ... it moved his hand inch by inch towards the chain upon his neck").
It doesn't seem to be clear whether the command Frodo receives is from the Ring Wraith of Sauron himself. If the command is from the wraith alone, then maybe all this shows is that wraiths aren't quite strong enough to bend Frodo's will.
If, however, it comes from Sauron, then it seems that it is possible to resist his will if it goes againt one's own. Perhaps this means that Sauron convinced the Nine that they wanted to do his will (without esp/whatever) so that they would be 'receptive' to his will. Perhaps the rings weakened their own wills.
Perhaps my whole post is pure speculation which will be dismissed by someone better-read than me [img]smilies/wink.gif[/img]
And of course, this doesn't answer anything really about the 'mechanics' of how Sauron could impose his will on others.