Not that this isn't a well-known story, but: I was at the Smithsonian American history museum today and saw FDR's revisions to his Pearl Harbor speech.
I think revisions, generally speaking, are where stories are made. And I love self-edits -- when a writer takes a second (or third, or fourth, or ...) look at what he or she has written, and sees it more clearly or in a different light. That new look often results in revisions that make the story, or, in this case, speech, better. (I'm distinguishing here from writers who pick away at their stories for no reason other than they can't bear to let it go).
In FDR's speech, the original line was, "Yesterday, December 7, 1941, a date which will live in world history, the United States of America was simultaneously and deliberately attacked by Naval and air forces of the empire of Japan."
I don't even know what "simultaneously" was ever doing in that sentence. But when FDR changed that to "suddenly" and changed "world history" to "infamy," he gave us the speech's most memorable line.