There are thousands of good reasons why magic doesn't rule the world. They're called Witches and Wizards.
Terry PratchettDestiny is important, see, but people go wrong when they think it controls them. It's the other way around.
Terry PratchettHe talks pretty big for a gutter wizard," he muttered. "You don't understand at all," said the wizard wearily. "I'm so scared of you my spine has turned to jelly, it's just that I'm suffering from an overdose of terror right now. I mean, when I've got over that then I'll have time to be decently frightened of you.
Terry PratchettThe stories never said why she was wicked. It was enough to be an old woman, enough to be all alone, enough to look strange because you have no teeth. It was enough to be called a witch. If it came to that, the book never gave you the evidence of anything. It talked about "a handsome prince"... was he really, or was it just because he was a prince that people called handsome? As for "a girl who was as beautiful as the day was long"... well, which day? In midwinter it hardly ever got light! The stories don't want you to think, they just wanted you to believe what you were told.
Terry Pratchett