It's pretty clear by now that trilogies are important in film history. From The Godfather to the "Before" trilogy, good trios have proven worthy of the love of the masses. Sometimes it's hard to complete a story in just one film. In that case, you make three. Three great stories, all complementing each other to a degree of visual and literary perfection. Sometimes trilogies don't work. You make one great movie and the other two just don't live up to it. I'm looking at you, Star Wars prequels. Not you, "Revenge of the Sith," you are amazing. Keep being you.
On the other hand, some trilogies knock it out of the park. When a trilogy works, it's a thing of beauty. Not all of them tell a continuous story, and some of them are three-film arcs within a franchise. Three great movies make one phenomenal trilogy.
