It seems somehow appropriate to discuss this on April Fool's Day.
Joseph Campbell was a Mythologist - a student of mythology, and to some extent, comparative religion. He became famous for popularizing the concept that all myths - all stories, really - are simply variations on The One Story. That is to say, that there's a certain framework that all myths fall into, which is a way of showing the fundamental psychological interconnectedness of all things blah blah blah blah. It's the kind of thing that wild-eyed accademics in the mid-19th century went even wilder-eyed about because it's basically reductive thinking: It turns big, scary, inscrutable, and generally (Gasp!) non-Caucasian societies into something you can dismiss with a wave of your pseudointellectual hand. The beauty of this is that it allows white folks to tell non-white folks what non-white folks believe and think without ever botheirng to ask them, nor even considering their opinions in the first place.