[Arvegil145]

Concerning the notion that the Ring has no power over Tom, I think many are mistaken in that view. Tom is neutral. He desires nothing. He is like a walking, talking, singing personification of Switzerland. The Ring simply cannot find anything that would affect him, anything that would lure him into a Gollum-like possessiveness.

And the fact that the Ring did not make him invisible is, to me at least, not that great a wonder. You have to remember that the Ring puts its wearer into the wraith world. And you also have to remember that the Elves, for example, live in both worlds - the visible and the invisible (wraith-like, for lack of a better word). So it is my opinion that if, say, an Elf put on the Ring he would not become invisible.

And the conclusion to all of this is that Tom Bombadil lives in both worlds, like the Elves, the Maiar, and the Valar (which doesn't necessarily mean that he belongs to any of those that I named).