Pratchett Terry: Sourcery (Discworld Novel #5)
Sourcery (Discworld Novel #5) - Terry Pratchett. There was an eighth son of an eighth son. He was, quite naturally, a wizard. And there it should have ended. However (for reasons we'd better not go into), he had seven sons. And then he had an eighth son...a wizard squared...a source of magic...a Sourcerer. ...a dál?