I'm currently working on a novel that has been bouncing around in my head for a while. It's gotten to the point that I have two distinct classes, one that is very exclusive and can control the elements of fire, water, air, and earth, and the other class can essentially cast spells. The spell casters can enter this other world which is a mirror image of the natural world. Everyone else cannot. My main issue I think is I'm not entirely sure how to populate the rest of the natural world. Who are the commoners? I'm having difficulty with that. I almost want to take a Tolkien-ish route and create only two or three other groups to populate the rest of the natural world, but I don't know if that would be the best way. Any advice in general on this subject would be helpful. Thanks!!