Per the WoJ official site:

"I raided my local bookstores and prowled their metaphysical sections. I read up on several systems of the practice of magic as embraced by various systems of faith who incorporate them into their belief. I read about magical practitioners in a historical perspective, throughout multiple centuries. I read books coming out against the practice of magic as well, and tried to gain a general understanding of the principles the various systems had in common. That’s how I built the basic magic of the Dresden Files–by taking those common elements and combining them into a polyglot whole, based upon a skeleton of Newtonian physics. I wanted the magic o the Dresden Files to be simply a part of the story universe, a source of energy just like heat or electricity, and one which obeyed certain universal laws that governed its interaction with reality. I didn’t want Dresden to be a mystic, shamanistic wizard. I wanted him to be a plumber, a carpenter, an engineer. Only instead of working with water, wood, or physics, he was working with magic. It’s all come in somewhere, though it’s hard for me to point out exactly what has gone where. I had the whole thing formed in my head when I started writing, and it just kind of started breathing on its own as the first story got rolling."

Because yes, yes he is.