"That's why there were postmen, with real feet. That's why the clacks were a string of expensive towers. Come to that, it was why farmers grew crops and fishermen trawled nets. Oh you could do it all by magic, you certainly could. You could wave a wand and get twinkly stars and a fresh-baked loaf. You could make fish jump out of the sea already cooked. And then, somewhere, somehow, magic would present its bill, which was always more than you could afford.
"That's why it was left to wizards, who knew how to handle it safely. Not doing any magic at all was the chief task of wizards -- not "not doing magic" because they couldn't do magic, but not doing magic where they could do and didn't. Any ignorant fool can fail to turn someone else into a frog. You have to be clever to refrain from doing it when you knew how easy it was. There were places in the world commemorating those times when wizards hadn't been quite as clever as that, and on many of them, the grass would never grow again."
It's funny. The characters in your head are always with you, and the one that shames me by reading Crime and Punishment in the original Russian and who can't stand fantasy, poked her nose into what I was reading and simply said, "Exactly." (Okay, in all fairness, the character doesn't like fantasy more because it reminds her of *home* than because of any highbrow literary persuations, but it's still funny.)
I'll have to remember it, though, because another character very close to said character might want to use the quote in a bit. We'll see. %)