[Nilpaurion Felagund]

I think (as already had been said in this thread quite a few times) there are two kinds of “magic” in Middle-earth: technology, and the alteration of the Music. In this post I shall be looking at the latter.

Music shaped Eä. Those who can listen to its echoes can learn more about the world. The land continually tells its tale, or, rather, sings its songs, and someone who know what to listen to can hear its voice (qq.v. Voronwë in Ivrin, Legolas in Eregion). In these two instances one can even see the active use of music in “magic”. (WARNING: Speculation ahead.)

Ivrin: This lake and Helevorn were defiled by Glaurung, accompanied by Orcs. But I don’t know how anyone could do that. Were the Orcs carrying huge loads of filth to dump in the lake? But that would not be enough. Perhaps Glaurung, or, through him, Morgoth, sang that the lake was no longer clean. That could make it susceptible to the filth it receives.

Eregion: How did the stones know they were delved, builded, or wrought. Surely they have no tactile sense! Perhaps the Noldor sang songs to the stones while they were being worked on (cf. The spell of Felagund that bound the stones of Minas Tirith).

These are but speculations on how music could affect even the stuff of Arda, but I think they are in the realm of possibility in Arda. As for technology, well, some of the posts above have dealt with the subject better than I could.