When you're designing your magic systems, what is it you typically go into?
At that thing I said, brandonsanderson.com/writing/advice, I've got three essays on magic systems that can cover it way better than talking about it right now. That'll get you really into it. I would suggest those, they're called Sanderson's Laws, because I'm really humble. Asimov has them, and Clarke has them; so I can have them, there's not fantasy guys who have laws. So go read those, and they will talk you through how I develop a magic system.
I was wondering about the background behind one of them. Stormlight.
Background behind the magic system in Stormlight traces back to my early history as a science major. I was a biochemistry major in college, before I jumped ship to English. And I've always been interested in the sciences quite a bit, and you'll see that in writing as a theme through my magics. The magic system of Roshar is based on the idea of the fundamental forces. I love the idea of the fundamental forces. This idea that there are certain interactions between parts of matter and energy that transcend everything else and rule how our entire world works was fascinating. So I wanted to come up with this idea of ten fundamental forces that worked with the magic system of the cosmere. Because there are extra forces, because there's weird stuff in the cosmere. Some of them are one-to-one. Gravitation is just one of the fundamental forces. And the strong and weak forces, I played with and came up with some things for that too, so you'll see that. But on the other hand, we've got things like transcending between the Physical Realm and the Cognitive Realm, which is a very cosmere-type thing. So, I built ten fundamental forces. And then I was playing with the idea (which I have in the cosmere) of pieces of energy becoming sapient. You've seen it happen in Elantris, you've seen it happen in Warbreaker. Way of Kings is one of the places I really wanted to show off how this works. So, the idea of the spren connecting a bond to the force that they're related to in certain ways, that just grew out of that.