In 1947, Kurt Vonnegut, then an anthropology student at the University of Chicago, wanted to write a master's thesis about how basically how every story ever told in history can be described. Vonnegut has a theory that every story basically belong to one of eight archetypal "shapes."
His thesis proposal was rejected, Vonnegut said, because "it was so simple and looked like too much fun." Soon afterwards, Vonnegut left school to work but he maintained the idea and later developed into "The Shapes of Stories" as shown in this 2005 lecture (yes, covered previously on Neatorama back in 2011, but it's worth a revisit):
I want to share with you something I’ve learned. I’ll draw it on the blackboard behind me so you can follow more easily [draws a vertical line on the blackboard]. This is the G-I axis: good fortune-ill fortune. Death and terrible poverty, sickness down here—great prosperity, wonderful health up there. Your average state of affairs here in the middle [points to bottom, top, and middle of line respectively].
This is the B-E axis. B for beginning, E for entropy. Okay. Not every story has that very simple, very pretty shape that even a computer can understand [draws horizontal line extending from middle of G-I axis].
Now let me give you a marketing tip. The people who can afford to buy books and magazines and go to the movies don’t like to hear about people who are poor or sick, so start your story up here [indicates top of the G-I axis]. You will see this story over and over again. People love it, and it is not copyrighted. The story is “Man in Hole,” but the story needn’t be about a man or a hole. It’s: somebody gets into trouble, gets out of it again [draws line A]. It is not accidental that the line ends up higher than where it began. This is encouraging to readers.