I believe the source of this quote is Joseph L. Mankiewicz.

Keep Writing!
Mike

Great line.

Another difference is that there is no magic words that will make a character step out as new.

I know, I've tried. I said the magic word, the guy looked at me with stunned surprise, he said "I'm sorry you feel that way" and then nothing more happened...

Bogart says it in "The barefoot Contessa" (which is written by Mankiewicz)

Thanks, Mike and Timo. I've seen The Barefoot Contessa - many years ago - and completely forgot that line.

The original quote is by Tom Clancy-
'The difference between life and fiction? Fiction has to make sense.'

Mark Twain said something like that. "The difference between truth and fiction is that fiction must be believable."

I've since heard it stated by tons of different people, from Joe Mankiewicz and Tom Clancy to Truman Capote and Charles Ripley. But Mark Twain is the earliest originator that statement that I am aware of.