So when we last looked at this unnamed fantasy world we had decided that there would be 2 forms of magic: an old form, and a new form. The central conflict of this setting will be between these two concepts so they need a good bit of thought.
Since the new magic is supposed to be analogous to the emergence of science during the enlightenment, it would follow that the new magic should be based on formalism, math and laws. Since the new magic is well... new, it follows that it should be mostly undeveloped, with a lot not understood. On the other hand, in order for the conflict to be one worth worrying about new and old magic should be able to compete, so there has to be some advantage to the new magic. It makes sense from the central analogy again that the main advantage would be repeatability and universality: new magic is just another physical principle that can be manipulated by anyone who understands it. Thus it's much easier to train someone to be a new mage, but they are much less powerful.
Now if the new magic is all about repeatability and formalism, then old magic should be about tradition, but what are these traditions? It's not that the old mages were pure empiricists, just knowing that when you chant these tree words and wave a wand you make a fireball, rather they had their own ideas about how magic works, they just are much less formal, and rooted in tradition, religion, and mysticism. Now since there are as many traditions as there are societies, I'm going to focus on one region that for now we'll call "the west". The western tradition of magic is going to be modeled on medieval Catholicism, and is basically based on the idea that by sacrificing to the god of the western religion you can get miracles on demand. This leads to the idea of what sort of sacrifices could be made. These could be anything from material goods to personal health, to abstract things like your conscious humanity, and obviously the bigger the sacrifice the bigger the magical effect.
[as a side note, if I wanted to make this into a game (a tabletop RPG perhaps) it would make sense to spell out the different sacrifices possible, and possibly have different groups that specialize in different types of sacrifice]
Now we can start to put together the theory of new magic: there is invisible flows of mana all around us, and these flows are affected by the human mind. Things that people value become saturated with mana, and can be released by destroying the thing of value. New magic has found a way to store these flows of magic artificially, providing a good supply of low-level magic, but they cannot get the densities of mana that the old magic can, and this artificially stored mana is not as easy to control as "natural" mana. This means that most new magic ends up being more like engineering than magic as usually thought of, however it is magic not science, and has a whole other set of rules.
Next time I'll talk about politics and such of the new magic vs. old magic dynamic.