I was listening to a podcast the other day where they were discussing magic in films.
The general opinion was that magic is a terrible idea in movies because it makes anything possible. Your hero is stuck in a jail? One quick spell and she's out. A terrible villain breathing down everyone's neck? Wave your magic wand and all is well.
Not the most subtle argument against magic in films, but there is a good point in there. In short, for magic to actually work in narrative terms, for it to have a part to play, there needs to be something standing in its way. If everyone can do it, then why don't they? Fear? Suppression? Both good, but for me the main thing is that magic is damned difficult. And there's a very good reason why.
Language, as you will know, bears no direct relationship with the things it represents. The sign and the signified are separate and the link between them is entitrely arbitrary. There is nothing dog-like about the word 'dog'. If there is, then how do we explain the gazillion other words for dog in countless other languages? But for magic to work, or, more accurately, for spells to work, there needs to be a direct link between the word spoken and the thing it speaks of. There must be something that binds the thing that is a dog to the word that represents it. How, otherwise, would you be able to say words and have those sounds make real changes in the actual world?
It follows that any language that connects directly with the real world must not only have a lexicon beyond comprehension, but will also require a grammar complex beyond words. With a language so complicated, the only way to make it work, to ensure the recitation of a spell has the desired outcome, is to have the intelligence and gift for languages capable of taking on such a mammoth and complex linguistic task. And you'd have to be jolly clever to boot.
So magic becomes the preserve of the gifted few, of those capable of committing immense amounts of time to learn its infinite variety. Men and women who must lock themselves away to even begin to grapple with this challenge. Preferably somewhere quiet. That is, sorcerers.
In The Blade Bearer, Rayne of Irenia explains all this better than I have, by the way.