Magic in Middle-earth

[Garen LiLorian]

Most instructive, Fordim. I learn something new every day around here.
And, although that all makes sense, why does Tolkien then only use 'spell' in a context that could mean magic? At other times, when the 'convincing' is a bit more mundane, there is no mention of spells. (See Theoden and Bilbo) Indeed, with Bilbo, although Gandalf does a good deal of convincing, he later tells Frodo that Bilbo gave up the ring of his own accord. I don't actually know what that might mean, but it seems to be significant somehow. I mean, if he was compelled by spell to give up the ring, gandalf says that it would break him. (well, actually Frodo. But, since Frodo had had the ring at that point for about 24 hours, we may assume that it would have broken Bilbo as well)
Although, I still don't really get why spel makes it not magic. Wherever the word came from, it certainly now carries the magic connotation. I can't remember where the quote is from, but I've always agreed with whoever said "ninety nine percent of magic is simply knowing one extra fact)