From the book “Mess Effect”: In Return of the Jedi , the good guys win because of love. Luke finds the strength to overcome Vader without resorting to the dark side because of his love for his sister. In turn, Vader betrays the dark side because of his love for his son. Han and Leia overcome the stormtroopers because of their love for each other, which Han finally professes right at a crucial moment. And the Ewoks overcome the Empire because of George Lucas' love of merchandising.