Believable Fantasy

I learned years ago from Lester del Ray that the secret to writing good fantasy is to make certain it relates to what we know about our own world. Readers must be able to identify with the material in such a way that they recognize and believe the core truths of the storytelling. It doesn't matter if you are writing epic fantasy, contemporary fantasy, dark urban fantasy, comic fantasy, or something else altogether, there has to be truth in the material. Otherwise readers are going to have a tough time suspending disbelief long enough to stay interested.

Terry Brooks, Sometimes The Magic Works, 2003