Whenever you’re telling mythological stories, you’re travelling in circles. Like in a mandala there are small circles and bigger and bigger circles until finally you encompass the universe. It’s the same thing telling stories, in that every person, or relationship or group of symbiotic relationships, is always travelling in a circle. It goes back to either where it started or it intersects with other circles. At the end they survive because they’re all connected. In Episodes I, II and III, all the symbiotic relationships are torn apart. In Episode I, the Senators are more interested in themselves than they are in helping each other. They have fallen out of the symbiotic circle. They couldn’t agree on anything because their interests became so divergent, so they couldn’t get anything done as a Republic, and the Chancellor uses this division, which he helped create, to become Emperor.

In Episodes IV, V and VI, the Rebels form their own symbiotic relationship from the Old Republic to fight the Empire. They’re trying to restore balance.
If you get into the ecology of it then everything is connected. Everything. If something happens to one part, then it happens to all parts, and that, ultimately, is one of the main movements in Star Wars.

This is the cosmology, the Force is the energy, the fuel, and without it everything would fall apart.

The Force is a metaphor for God, and God is essentially unknowable. But behind it is another metaphor, which fits so well into the movie that I couldn’t resist it.

Midi-chlorians are the equivalent of mitochondria in living organisms and photosynthesis in plants – I simply combined them for easier consumption by the viewer. Mitochondria create the chemical energy that turns one cell into two cells.

I like to think that there is a unified reality to life and that it exists everywhere in the universe and that it controls things, but you can also control it.

That’s why I split it into the Personal [Living] Force and the Cosmic Force. The Personal [Living] Force is the energy field created by our cells interacting and doing things while we are alive. When we die, we lose our persona and our energy is assimilated into the Cosmic Force.

If we have enough midi-chlorians in our body, we can have a certain amount of control over our Personal [Living] Force and learn how to use it, like the Buddhist practices of being able to walk on hot coals. Some people can’t because they just don’t have as many midi-chlorians – that’s just genetics. So the more midi-chlorians we have, the more accessibility we have to the Force. So we have to be trained how to use it.

For example, we can be good at math and on the piano, but to become a physicist or concert pianist, you have to be trained. You have to be trained to use the Force, to use the genes that give you a talent that is different from everybody else.

So you have to be found and fostered. If you have more than a certain number of midi-chlorians, you can become a Jedi. The Jedi will train you to connect to your Personal [Living] Force, and then to connect to the Cosmic Force. You don’t have much power to control the Cosmic Force, but you can make use of it. The Jedi by nature of their genetics have more midi-chlorians than most people, but there is no direct connection between our human world and the microscopic world.

The Jedi are good, but they are not fantastic. They were never designed to be a superhero or anything like that. They were designed to be a Buddhist monk, who happened to be a very good warrior. And they became the peacekeepers of the human world.

As explained in The Clone Wars episode “Voices”, Qui-Gon Jinn spent time with five Force Priestesses on their planet, the Wellspring of Life. They explained to him how he could keep his persona when he died and joined the Cosmic Force.

Qui-Gon learned how to hear the Cosmic Force and when he died in Episode I he joined the Cosmic Force with his persona intact and was able to talk to Yoda in Episode III. When he was there, he learned more about how to become a Force ghost to keep your identity. Qui-Gon passed that information along to Yoda, Yoda taught Ben and Ben was teaching Luke how to do that.

So that’s how that symbiotic circle of people learned how to go from heaven to Earth, so to speak. It’s based on Greek mythology – how to become a god, but in a much more practical sense and without the ego, without the identity.

— George Lucas