68. star wars
This is a big movie in all ways. It is big in that it creates a world unlike we had previously seen in cinema (the now iconic "galaxy far, far away") and subsequently created a monster of a franchise that changed cinema forever, in distribution schemes to merchandising to using actors as puppets and more. But mostly what I mean when I saw that is it big is that it is a movie concerned with Big Ideas, while not eschewing the necessity of a tight plot as the engine to drive those Big Ideas along.
Big Idea One: Spirituality is just as important as science and maybe more so. Obi-Wan is spirituality, Han Solo is science, and Luke is in between. They duke it out on the ship while Luke practices his saber skills. True to the machinations of how Hollywood plots work, at the end of the 2nd act, Luke uses his science skills (piloting) along with his spiritual skills (The Force's ability to harness telepathy) to shoot down the Death Star. Considering how much discussion of The Force there is in the film, and the fact that Luke is able to continue to communicate with Owi-Wan after he's already dead, we can guess which side Lucas is taking in the face-off between spirituality vs. science.
Big Idea Two: The Hero Myth. Just as "The Matrix" synthesized influences ranging from kung-fu films to anime to vampire movies to cyberpunk books, Lucas took the melting pot that was his cinematic canon and combined it: 50's westerns, tv serials, soap operas, 50's sci fi, Kirosawa films, "Lawrence of Arabia", and especially, the ideas of Joseph Cambell in relation to the myth of the Hero. Here's a summary of the myth:
A hero ventures forth from the world of common day into a region of supernatural wonder: fabulous forces are there encountered and a decisive victory is won: the hero comes back from this mysterious adventure with the power to bestow boons on his fellow man.
The first trilogy is the process of how Luke Skywalker becomes a hero by defeating his father, who represents the Dark Side of the Force by way of the Empire. In this, the first film, he comes from a desert planet, decides to leave when his guardians are killed (bonus points for being an orphan), encounters a world of scary-looking space creatures and ships that either go light-speed or can blow up whole planets, and uses his newfound Force, along with his previous piloting ability, to thwart the Empire. Then he wins a medal from a cute girl (doesn't know she's his sister yet).
He is a hero by specific design, and becomes even more of one in the subsequent films.
By contrast, the second trilogy is the process of how Anakin Skywalker goes through a much similar course, but becomes a villain instead. He is a virgin birth (!) whose mother (?) is killed. He is a fine pilot and student of The Force, but becomes seduced to its Dark Side due to his desire for power and, especially, revenge.
He is a villain by specific design, and becomes even more of one in the subsequent films.
Big Idea Three: The role of the underdog and outsider. Lucas is interested in characters on the fringe, outside of the mainstream. Luke is from a planet on the far edge of the galaxy; Leia is a princess who, in our political parlance, has "gone rogue" and is "palling around with terrorists"; Han Solo is a pilot-for-hire whose last name is, well, Solo. These folks band together to take on the Empire, a highly scientific and powerful group who have developed technology sufficient to explode entire planets. How dare these ruffians try to compete with that, or to bring that down? But they do, because as the outsiders and the underdogs, they are hungrier.
I've heard the argument that this is actually Lucas' secret comment on the world of independent film vs. the Hollywood studio system. If so, I like that, because it means that he started out as Luke Skywalker and then became Anakin, and only wants our forgiveness for the mess he's helped make of the movie business in the process.