"If you make magic systematic and reliable ... It's no more a violation of reality than a Chevy station wagon would be to Charlemagne — a big surprise, but not an intrusion of a different reality."
There are, it seems to me, two worlds of fiction. There is the world within the walls of a specific type of fiction, and there is the world outside the walls.
puzzle pieces / fitted together / without a box lid
The UFOs in the sky over Portland look like hubcaps. Silver or chrome-plated saucers, all of them roughly the same size and all of them spinning, hang miraculously in midair, but most people either don't see them or pretend that they don't see.