"Your overconfidence is your weakness," Luke said, calmly.
"Your faith in your friends is yours," the Emperor replied.
Vader shook his head. "It is pointless to resist, my son."
"It is pointless to control the galaxy," Luke retorted. "I've learned things about the Force that mean I understand that now."
He waved his hand, and Vader tensed, but it turned out to be for emphasis instead of telekinesis. "The Force is everywhere. In everything. There's… a level of reality which is far beyond what we care about. It's around us, everywhere. Even in us."
"What are you talking about?" the Emperor asked, thrown off his argument about how everything was futile.
"The Force," Luke explained. "And… us. And everything, because the Force is everything. And we're the Force. We're… luminous beings, and our bodies are only crude matter that outlines them and gives our spirits somewhere to be."
"What are you on about?" the Emperor demanded. "Vader! What is he on about? Is this some kind of Jedi nonsense?"
"It is possible," Vader mused. "But I do not recall hearing it before."
"I can explain more, if you'd like," Luke said, earnestly. "The way that it works is that there's more than one layer of existence, and this is a layer of reality but compared to the Force it's just an illusion. Which means that – yes, you should do everything you can to make things better in this world, but – no, this world isn't all there is, and you aren't your body. Your body is just an approximation."
He looked at his hand. "I lost this on Cloud City and… it didn't make me any less of me. I'm still me, because I'm not my body, I'm the one who lives inside it. And the Force is like proof of that."
That drew a blank look from the Emperor, and what would probably have been a blank look from Vader.
"Elaborate," Vader requested.
"Well, we all know that the laws of physics exist, right?" Luke asked. "They define exactly how things work. How things fall, or they don't. How orbits work. And yet, I can stretch out my hand and pull something into it. Which means the laws of physics aren't laws, they're just very persistent illusions."
"I believe the interaction is mediated by midichlorians," Vader said. "They are like mitochondria for the Force."
"So?" Luke replied. "That simply means that part of how we are outside physical reality can be measured. I've heard the explanations, I've seen it – all that the explanation really does is put it into words, and give it a framework."
He made another expansive gesture.
"This is trite nonsense," Palpatine said. "Your friends on the Sanctuary Moon will not survive."
"And if that happened, I would be sad," Luke said. "Of course I would. But I came here willing to die, because death is not all that there is."
Palpatine glowered at Vader.
"This one is broken," he said. "Do you have another possible new apprentice for me?"
"The supply is a bit low, my Master," Vader said.
"And I know about your rebel fleet," the Emperor went on. "They will be ambushed by my fleet, just as an entire legion of my best troops is waiting for your friends."
"That's a shame," Luke said. "But it's not the same as something being unrecoverably bad."
Palpatine blinked.
"...what?" he said. "You make no sense."
"You can think of it like a shadow," Luke said. "Or a hologram. It looks real, but it's not the most real thing. It's illusion, just a very persistent illusion which is why so many are taken in by it."
"This doesn't sound very empirically sourced," Vader muttered. "Did you come up with all this yourself? If not, who taught you?"
"Yoda," Luke replied, and both the Emperor and Vader flinched slightly.
"Yoda's alive?" Vader asked, sounding horrified and fascinated.
"Not since… about three days ago, I think?" Luke answered. "I could be off by a day or two on that, I spent a lot of it in hyperspace."
The Emperor tried very hard to stifle a sigh of relief, and didn't quite manage it.
"You know Yoda?" Vader said. "You met Yoda?"
"Yes," Luke agreed. "I was there with him at the end. Obi-Wan told me where he was living."
"What?" Vader asked, now sounding baffled. "...how?"
It was his turn to wave his hand to make a gesture. "Because I remember Cloud City, and you were reasonably talented, but you seemed self taught. You did not fight like you'd had two and a half years of Ataru lectures from the death gremlin… there weren't nearly enough backflips for it."
"...oh, I see," Luke said. "No, Obi-Wan told me on Hoth."
"On… Hoth," Vader repeated, slowly. "He'd been dead for several years at that point. Hadn't he?"
"Oh, yeah," Luke confirmed, readily. "He's a ghost. He's still around."
The younger Skywalker shrugged. "Kind of proves what I was saying, right? Death isn't the end of existence. A person lives on after the death of their body. They become one with the Force, and the Force is one with them, but they still exist."
Vader was silent for a long time.
"...huh," he said, eventually.
"Anyway, as I was saying – Father – Your Highness," Luke went on. "I don't fear death because death is the loss of the crude flesh, which is just a cloak for our true selves, who are luminous beings of light. To ask others to accept suffering of the flesh is unfair, because they feel it as real, but I understand it for the illusion that it is and so I'm willing to suffer and die for my beliefs – in a very real sense, it doesn't mean as much to me as it would to anyone else. Because I know the truth."
"This is all the ramblings of a senile madman, translated through the mouth of a naive boy," the Emperor said. "What kind of proof could you possibly have?"
"...what, apart from the fact that I communicated with my dead mentor, and he gave me information that I did not know before?" Luke asked, curious. "That was sufficient for me to accept it when Yoda told me, but there's also the extent to which understanding the illusive nature of reality amplifies my understanding of what the Force truly is."
"I have to admit, it would explain why Obi-Wan vanished," Vader mused, sounding like he was talking to himself more than the others.
"You don't know about the Force," the Emperor said, snidely. "Certainly your understanding is not as deep as mine!"
Luke examined him.
"You actually believe that," he said. "But you think what I'm saying is nonsense?"
"If you understood the Force better, you would not be my prisoner!" the Emperor retorted.
"I'm not," Luke said. "That's an illusion as well."
"You cannot just declare anything you don't like to be an illusion!" Palpatine raged.
"I can if it is," Luke replied, still calmly, and reached out his hand. His lightsaber slapped into it, then he let go and it floated back across the room to where Palpatine had put it.
He shrugged. "I'm here because I want to save my father. I surrendered because I thought that would be the best way to do it. I'm standing here on a battle station I fully expect to be blown up, because I am committed to saving my father. From you. That's why I'm here, and it has nothing to do with you having any power over me. You don't."
The Emperor attempted to prove Luke wrong by electrocuting him, which lasted about ten seconds until Vader threw him out the window.
The air, on the other artificial hand, stayed put.
"You might be right, son," Vader said, sounding scientifically fascinated as the room didn't depressurise. "Accepting this really is helping me understand and use the Force."
"I'm glad to have helped," Luke replied, reminding himself that electrical burns were also illusions no matter how persistent they were. "What do we do now?"
"Leave the room, probably," Vader suggested. "Then we can see about deciding whether we want to keep this station or destroy it."
He made a curious noise with his respirator. "Are the Empire's succession laws real or an illusion? I am fairly sure I could abdicate in your favour if you would like."
"Mon Mothma would be better, I think," Luke said, after some consideration. "Or Lando. Lando might work."
AN:
Luke as a preacher and the concept of reality versus illusion.