I have to agree with Amanita here!! The beauty of Magic is that we can create it inside our own worlds in so many different ways, we are free, and following rules or something that is supposed to apply for all Fantasy in general would only limit our creativity as writers and storytellers...
After all, different stories work with different styles of Magic, and the style that exists in a particular story or world would not work well for some other stories: The Magic in Lord of the Rings would not work well with my worlds at all, and the addition of my own Magic to the Middle-Earth world would just completely ruin the story!!
The style of Magic that you create and use in your stories must follow the rules and limits necessary for your own story =)
After all, different stories work with different styles of Magic, and the style that exists in a particular story or world would not work well for some other stories: The Magic in Lord of the Rings would not work well with my worlds at all, and the addition of my own Magic to the Middle-Earth world would just completely ruin the story!!
The style of Magic that you create and use in your stories must follow the rules and limits necessary for your own story =)