I have plowed through dozens of pages of what will probably be a novella. One character just made a smart-alecky and very silly comment to another, who will briefly think of it as a silly comment.
That was the original inspiration for the story. But it's not quite Tolkien's observation that he wrote The Lord of the Rings to have a world with the greeting "Elen sila lumenn’omentielvo, a star shines on the hour of our meeting," because I'm not even sure it will stick around. . . after revision.
Sometimes the original inspiration doesn't even make it into the outline, so it's gotten farther than most.