Once upon a time is open to all I think and that the narrative should be an important part of the image. A forest, old building, abstract, or fractal I think you get the idea.
The reason why the sun sets in the evening is because it wants to see the sunrise in the morning. I rise in the morning because I want to see them both. RvdB
In the old Peanut's cartoon,Snoopy's stories always started out "It was a dark and stormy night ..." Supply an illustration or photo for Snoopy's book.