George Lucas 2010, at the Clone Wars Writers’ Meeting:
The core of the Force–I mean, you got the dark side, the light side, one is selfless, one is selfish, and you wanna keep them in balance. What happens when you go to the dark side is it goes out of balance and you get really selfish and you forget about everybody … because when you get selfish you get stuff, or you want stuff, and when you want stuff and you get stuff then you are afraid somebody is going to take it away from you, whether it’s a person or a thing or a particular pleasure or experience.
Once you become afraid that somebody’s going to take it away from you or you’re gonna lose it, then you start to become angry, especially if you’re losing it, and that anger leads to hate, and hate leads to suffering. Mostly on the part of the person who’s selfish, because you spend all your time being afraid of losing everything you’ve got instead of actually living.
Where joy, by giving to other people you can’t think about yourself, and therefore there’s no pain. But the pleasure factor of greed and of selfishness is a short-lived experience, therefore you’re constantly trying to replenish it, but of course the more you replenish it, the harder it is to, so you have to keep upping the ante. You’re actually afraid of the pain of not having the joy.
So that is ultimately the core of the whole dark side/light side of the Force. And everything flows from that. Obviously the Sith are always unhappy because they never get enough of anything they want. Mostly, their selfishness centers around power and control. And the struggle is always to be able to let go of all that stuff.
And of course that’s the problem with Anakin ultimately. You’re allowed to love people, but you’re not allowed to possess them. And what he did is he fell in love and married her and then became jealous. Then he saw in his visions that she was going to die, and he couldn’t stand losing her. So in order to not lose her, he made a pact with the devil to be able to become all-powerful. When he did that, she didn’t want to have anything to do with him anymore, so he lost her.
Once you are powerful, being able to bring her back from the dead, if I can do that, I can become emperor of the universe. I can get rid of the Emperor. I can make everything the way I want it. Once you do that, you’ll never be satiated. You’re always going to be consumed by this driving desire to have more stuff and be afraid that others are going to take it away from you. And they are. Every time you get two Sith together, you have the master, the apprentice, and the apprentice is always trying to recruit another apprentice to join with him to kill the master. The master knows that basically everybody below him wants his job.
Only way to overcome the dark side is through discipline. The dark side is pleasure, biological and temporary and easy to achieve. The light side is joy, everlasting and difficult to achieve. A great challenge. Must overcome laziness, give up quick pleasures, and overcome fear which leads to hate.
These themes are repeated in this 2012 interview with Bill Bradley. One of the themes that came up again was that the two sides of the Force were about selflessness vs selfishness, about a compassionate person vs a person consumed with self-interest. That we all have good and evil in us, that we all have the compassionate side and the selfish side in us. And the idea is to keep those things in balance.
That the Force is based on the core theme of just about every religious mythology ever–the struggle between good and evil, that both are elements present, but that we strive towards the good, towards love. That we struggle to overcome the temptations towards the dark that are part of us, that we embrace love as best we can.