As I've said before, I have become absolutely intrigued with the Diablo books, mini-series etc and been reading all of them. After finishing the Sin Wars, and waiting to start The Order (P.S. To anyone who's read The Order, if I read it before I finish D3, am I looking at any spoilers? I would rather the book not spoil the game)
But as I was playing D3 last night I began to wonder - How do magicians live....
Inarius and Lillith made the Sanctuary with everyone else. Then -they- populated it with Nephellem (I forgot spelling.) They had magic powers, until the whole war where they made a pact and reset time, and locked away their powers. So everyone had their powers locked (Which I imagine once Diablo showed up in D1 it would start "unlocking" powers maybe?) But the mage in D1 had legit magic. Not scrolls, but spells he actually knew. Same with most of the people in D2, and the people in D3.
D3 makes sense because now the entire concept of Sanctuary is jacked. I know Cain's people can read runes, and cast spells because of who they are, but why can these "Mages" and people in the guild do it? It's truly confusing me... Does anyone have the ability to do it, or maybe are the powers just slightly awakened on some people?
I think based off readings, that people with "magical talent" are like Uldyssian, they naturally have some immunity to the soulstones control. Practicing this "magic" strengthens them to an extent. But like Uldyssian there is a limit and without someone like Lilith to awaken the power more, you can only go so far with the worldstone around.
The D1 manual actually had a blurb about the source of magic, albiet it has likely been retconned several times by now through all those books I haven't bothered reading. Anyway here it is as transcribed by DiabloWiki:
Magic is an extremely powerful force, the manipulation of which is carefully studied, frequently learned, but it is never fully mastered. Enchantments exude an aura that can be sensed by many, but years of training are required to properly exploit the Mana that pervades our world.
Some scholars use natural manifestations to explain the workings of the universe. In a common archetype, the physical world is likened to the sky while the ethereal realm of magic is set as the ocean. If we follow this line of thought, spells are much like the turbulence that occurs where the two interact with each other. During the Sin War, Demon and Angel alike wrought powerful magicks that threatened to tear the fabric of reality apart. The physical and magical realms began to blur and merge, which, in our archetype, would be the equivalent of a fierce hurricane.
The Forces of Order sought to preserve our reality by limiting the power of mortal man. As a consequence, only the strongest wills can harness more than the most basic of magical effects. Even then, much energy is lost in the transition of power between the two Realms. As a practitioner of the arcane arts grows more knowledgeable he is able to create these effects with greater efficiency, resulting in spells that are more potent, have more endurance and drain less Mana in their casting.
Trying to fit this together with modern lore, you can replace "forces of order" with the "worldstone" (texts written by the horadrim wouldn't know any better anyway) Not sure how this etheral realm energy works out in the modern view, although we saw some shadow realm where Koule was bound. In any case this parallel realm of mana is all around, just requiring some willpower to harness it and cause an interaction with our physical world.