In the 1949, Joseph Campbell published the book The Hero With A Thousand Faces. His basic premise was that there are certain themes that occur in virtually every hero story in every mythology in every culture. In trying to figure out why this was so, he did two things. First, he analyzed myth using the symbols of psychology and archetype, which are generally used to analyze dreams. Second, he outlined what the standard hero story, which he called the "Monomyth," consisted of.
The latter part of the book has inspired many dozens, hundreds, or maybe thousands of writers to copy the Monomyth in their own stories. Perhaps the most notable example is George Lucas, who based the structure of his Star Wars series entirely on Campbell's work. Lucas was so grateful that when Bill Moyers wanted to interview Campbell and contacted Lucas for permission to talk about Star Wars, Lucas offered up Skywalker Ranch for their use in filming the interview.
Those interviews became the PBS mini-series "Joseph Campbell and The Power of Myth." If you have not seen these, I highly recommend them. Even if you do not agree with everything Campbell says, he says it in such an engaging way that it will at least make you reevaluate many of your existing ideas. The series is available on DVD (finally) and you can get it just about everywhere.
There has been some controversy about Campbell's ideas, but I note that it all surfaced after his death in 1987. I suspect that his critics would have been cut to ribbons if they'd actually debated Campbell face to face.
Love him or hate him, I believe that Joseph Campbell was one of the greatest minds of the 20th Century. Every time since seeing "The Power of Myth" that I have been asked the old rhetorical, "if you could have dinner with any one person, living or dead" it has been no contest.