In the course of the Jeweled Amber campaign one of the Cousins, newly arrived in Amber came upon Prince Bleys reading in the library. Since this august personage had been assigned the duty of educating the newly arrived lordlings the Cousin sat at prince Bley's table without preamble. She asked Bleys why the Library of Amber had such an incredibly huge section of fiction works, far more then histories, technical manuals, magical books, and other more practical tomes?
Bleys casually looked up, took a long tug on his tankard and said, "Fiction? You think those books are fiction?"
She replied, "Well, yes, they are."
Bleys laughed, "Those aren't fiction books, they are Travel Guides"
He went on to explain that since everything could be found in shadow then fiction in one shadow was a history in another. So over the centuries the Elders had collected these books to help each other know how to find these places and what to expect once they got there.
He picked one at random and handed it to the Cousin and said, "Here. Read this. Learn its landscapes, people, history, struggles, foods, and for the sake of the Unicorn, the right color of the sky. Come back when you are done and we will go visit it."
Little did he know what a mess he had just gotten himself, the fresh young amberite , many of her fellow Cousins, and eventually Amber itself into.
The upshot of the comment was that Fiction was Reality.