One of those conversations
Driving, Sebastian and I in the car.
"Daddy, is magic real?"
"Well...not really. There are people who do tricks with cards and things, magicians, but those aren't real magic - not like casting a spell or anything like that. Real magic doesn't really happen. Except...well, I think it was magic that Mamma and I made you!"
"What about Santa Claus? He's real!"
(Uh-oh.) "Hmm. That's a tough one. I guess...I guess Santa Claus falls into a special category."
Long pause. Then, Sebastian said, half to himself, "I have absolutely no idea what he meant by that."
"Daddy, is magic real?"
"Well...not really. There are people who do tricks with cards and things, magicians, but those aren't real magic - not like casting a spell or anything like that. Real magic doesn't really happen. Except...well, I think it was magic that Mamma and I made you!"
"What about Santa Claus? He's real!"
(Uh-oh.) "Hmm. That's a tough one. I guess...I guess Santa Claus falls into a special category."
Long pause. Then, Sebastian said, half to himself, "I have absolutely no idea what he meant by that."

no subject
Would it be a useful definition to say that "magic" is what people call things when they don't understand how it works, but it does? Covers the Arthur Clarke definition, as well.