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It is written in the Silmarillion , in the chapter "Of the coming of Men into the West", p. 168:
"Now the Eldar
were beyond all other people skilled in tongues; and Felagund"
(King Finrod Felagund of Nargothrond who eventually died fulfilling an oath to
Barahir, Beren's father, when he followed Beren into Thangorodrim and there fell
into darkness and was slain by a werewolf, even as he slew it, but I digress.)
"discovered also that he could read in the minds of men such thoughts as they wished
to reveal in speech."
This passage is omitted in all other
versions of the "Quenta Silmarillion", but as the Silmarillion
later then these I would take it to be true. Whether this ability was
given to all elves, all the Noldor or only the high among the Noldor or
is not known to me.
It was said (Lord of the Rings) that Galadriel could read the hidden secrets of men's hearts. It would appear that if she had this ability it was augmented by her Ring, one of the Three, (Nenya), for she was able to read the hearts of Gimli and Legolas as well (The Fellowship of the Ring: "The Mirror of Galadriel".).
The Orcs are but perverted versions of elves so likely if they have it normal elves do. It would appear they don't for they had to torture Frodo and others (LOTR) In order to make them talk. Whether as Varda (guild member, not book character) suggested, it's strength might depend on whether the mind readee was fond of the mind reader, would also help to decipher this mystery were it known. I am forced to conclude from the limited information that it is not known who had it, what was the extent of the ability, and what it depended on. I leave it up to you, the reader, to decide for yourself.
Lord of the Rings : FotR "The Mirror of Galadriel"
Silmarillion "Of the coming of Men into the West"
Related articles: See also the ability of prophecy
"Mythological Themes in the Works of Tolkien" by Irmo-(Valar)
(Ed. note: paper removed at Irmo's