How we cite our quotes: All quotations are from Star Wars: Return of the Jedi.
Quote #1
THE EMPEROR: Rise, my friend.
DARTH VADER: The Death Star will be completed on schedule.
THE EMPEROR: You've done well, Lord Vader. And now I sense you wish to continue your search for young Skywalker.
DARTH VADER: Yes, my master.
THE EMPEROR: Patience, my friend. In time, he will seek you out, and when he does, you must bring him before me. He has grown strong. Only together can we turn him to the Dark Side of the Force.
Here we have the two biggest abusers of the Force in the entire galaxy. First, they're going to use it to track Luke down. Then they're going to use it to ruin him.
Quote #2
YODA: Soon will I rest; yes, forever sleep. Earned it, I have.
LUKE: Master Yoda, you can't die.
YODA: Ah. Strong am I with the Force, but not that strong. Twilight is upon me, and soon, night must fall. That is the way of things. The way of the Force.
Like most spiritual tenets, the Force is shrouded in mystery. There's an "it is what it is" quality to it that requires believers to put faith in something greater than them. In other words, Yoda's going to die because that's the way it goes. There's nothing he or Luke can do about it. Womp womp.
Quote #3
YODA: Remember, a Jedi's strength flows from the Force. But beware: anger, fear, aggression—the dark side are they. Once you start down the dark path, forever will it dominate your destiny.
Here, Yoda sums up the duality of the Force: Your spirituality will make you wicked strong, but if you put your faith in power and aggression, it'll lead you to the Dark Side and just make you wicked, period.