This entry doesn't feel like a complete thought to me, basically some observations on notional "magic" and the rules for developing and implementing the same. Conceptually there has been a lot of work done on Magical systems, both from a technical point of view and story point of view, very little of which seems referenced :-).

Typical RPG systems use magic either entirely, or mostly entirely, for combat. Meaning attacking and defending against attacks (physical and magical) which result in damage to the player or the opponent. And unlike Magic in books like the Harry Potter series where it has more of a 'tool' nature (travel, lighting, retrieving things, fixing things, cleaning, Etc.)

That said, having dabbled in game design I have found that "real world" things like economics and physics express self contained and dynamically stable systems. That can be useful in the fantasy world given that one ever burning fire spell could burn everything in the game universe if there wasn't something which prevented that from happening. So thinks like the inverse square law and conservation of (magical) energy really help out in keeping the game from becoming radically unbalanced.

When I read "The Magic Goes Away" by Niven I felt it was an interesting take on 'magic as alternate scientific thing' and Zelazny's unfinished "Changling" trilogy about magic in an alternate world an interesting 'magic is where you find it' sort of system.