The kinds of lessons weaved throughout the movie are also present in the original Wizard of Oz books, on which the film is loosely based, but in the original stories, there are so many limbs being lost in any given chapter that the heartfelt message gets a little buried. The original Wizard of Oz stories were told through a series of 14 episodic novels by L. Frank Baum, who wrote them in the early 1900s.