When I put magic into a book - whether it's a wizard or a crusty old werewolf - I'm asking a reader to swallow a huge leap that is counter to everything he or she knows. An extra big helping of reality makes that leap go down a lot easier.
Look at the average American diet: ice cream, butter, cheese, whole milk, all this fat. People don't realize how much of this stuff you get by the end of the day. High blood pressure is from all this high-fat eating.