If you use magic in fiction, the first thing you have to do is put barriers up. There must be limits to magic. If you can snap your fingers and make anything happen, where’s the fun in that? … The story really starts when you put limits on magic. Where fantasy gets a bad name is when anything can happen because a wizard snaps his fingers. Magic has to come with a cost, probably a much bigger cost than when things are done by what is usually called ‘the hard way.