What’s the theory of how the mechanics of magic work in the Buffy universe?
It seems to be a combination of: anyone can cast a spell, just by saying the right words and burning the right ingredients; and spells are effected by the will and innate magical talent of the spell-caster, with words, gestures, or ingredients entirely secondary.
There is some of each, essentially anyone can cast spells if they have the right words and ingredients. That type of magic seems to be more limited. (See, Xander casting a fire spell while reading from a book) This type can certainly be practiced and improved on. I would doubt that Giles has much innate ability, instead relying on his years of study and practice to perform rather formidible magic.
The second type would be innate ability. The examples here would be Willow and Tara. They both started out with the basic ‘say the right words and have the right herbs’ kind of magic, but quickly demonstrated an innate power. Willow basically got to the point where she could alter the world around her at will.
Another type would be demonic/god/other being magic. Creatures that are born/exist with innate powers. This would partially go with the 2nd type above, but would refer specifically to non-human beings. Some people also bargain with these beings to access power that is not really related to either type 1 or 2.
Anybody can learn, by dint of effort and study, to cook. But it requires inate talent to become a chef. Magic-users are cooks. Witches are chefs.
Do they ever give any explanation for why Willow is so powerful? As far as I know they don’t. Genetics, divine intervention, proximity to the Hellmouth or the Slayer, it would have been nice if they’d at least given at least a throw away line as an explanation.
There seem to be two basic types (at least, as far as humans are concerned): magic by ritual, and magic by will. Magic by ritual is something anyone can do, if they have the right books and paraphenalia. They can even do it by accident, such as Xander setting the book on fire by reading out of it.
With sufficient study, one can eventually learn magic by, which is what we see Willow and Tara doing in the latter seasons. I don’t think it’s necessarily innate: Willow had to do a lot of studying and practice just to get to the point where she could levitate a pencil. And major, hard core magic (like resurrections spells, or restoring souls) seem to still require a lot of ritual.
I think that, ultimatly, these are actually the same kind of magic. Spells require a degree of focus and willpower that most people don’t normally possess. A ritual puts the magic user into the proper frame of mind to channel the spell, but only temporarily. With practice, a human can learn to enter that state of mind with out the ritual. Even accomplished wizards still need to revert to rituals when casting extremely powerful spells, though.
Apparently, there are also ways of circumventing that process and tapping directly into major magic energies, but this is dangerous, and can carry a heavy price. This is what happens when Willow goes all dark and veiny after bad things happen to her girlfriend. My fanwank here is that part of the training and practice a wizard undergoes is learning how to control increasingly large amounts of magical energy. If they try to use a shortcut, and grab more power than they’re capable of controling, then the magic starts to control them. This happened when Willow went after Glory in season five, and that’s when she went from “regular witch” to “magic addict.” After Tara got shot, she did another huge power grab, and lost control entirely. The break between seasons six and seven, when Willow was with the coven in England, was spent helping her “digest” the huge amount of power she had unlocked in seasons five and six. What makes Willow an unusually powerful witch isn’t proximity to the Hellmouth, or genetics, or being buddies with a Slayer, but is instead due to her essential moral nature: she was able to take in so much magic energy that she turned “dark,” but still contained a strong enough core of decency to pull back. Most other mages who do what she did self-destruct, or are taken down by other powers. (Or succesfully blow up the planet, but that’s rarer.) Willow was able to make that sort of mystical power grab, and ultimatly emerge relatively unscathed, resulting in her having a huge degree of magical power at a very young age.
As fanwanks go this one’s not bad. Having magic be ultimately addictive and self-destructive helps explain why the Buffyverse isn’t crawling with witches and warlocks. Most of the ones we see seem to be well on the path to self-destruction as well, such as the Watcher lady with the magic lightning arm, or even Giles when he was still Ripper. There needs to be some check in place on magic because, as presented, it’s far too easy to use otherwise.