Inspiration is that Idea moment. You wake up, like VickiPettersson did, from a dream about a woman killing a man with the heel of a stiletto, and after you muse "what the ?" you decide to sit down and write the scene from your dream. And from it, and Imagination, you Invent a kick-ass, emotionally damaged heroine who is less human, and more important to humanity, than she knows, and from there you secure a publishing contract that results in a six-book series.
Or, if you're Diana Gabaldon, you watch a Dr. Who episode featuring an attractive young man in a kilt. You like men in kilts. You decide to Invent one, and because men in kilts are commonly Scottish, and kilts were more common day-wear a few centuries ago, you Imagine an 18th-century hero in a kilt, and well, from there, go on to become one of America's most-beloved best-selling authors whose eighth book in the Outlander series will be out later this year.
And if you're me, you find your Inspiration in your mother's story, a young, unmarried woman exiled by her mother to a Home for Unwed Mothers and forced to give her firstborn up for adoption, only you re-Imagine the outcome, Invent a character with the voice and courage that your mother did not discover until she was much, much older, and write the fairy-tale ending your mother deserved.
Imagination has always had powers of resurrection that no science can match. ~Ingrid Bengis