I've just had a thought.
Not an amazing thought, but one nonetheless.
The Original Trilogy (OT) has no mention of the Prophecy of the Chosen One, and why would it? Darth Vader was once Anakin Skywalker, and he and his master gripped the galaxy in its black glove. Yoda would have felt foolish for the cause of the Jedi's downfall being under their noses for over a decade (as he would for not sensing Palpatine for a lot longer than that) and besides, he couldn't tell Luke because that would give away Vaders identity. Any on-screen chat with Ben would make little sense in 1977-1983 and so...you get where I'm going.
The Prequel Trilogy (PT) is packed with mentions of midichlorians, prophecies and the like. Anakins presence is fortold, and his arrival greeted with suspicion and fear. The Jedi fear Anakin and his destiny, and yet the Jedi get it all wrong, allowing him to be influenced by the Supreme Chancellor and eventually falling prey to their own shortcomings. Yoda doesn't realise it until after his battle with the Emperor, and then it's too late.
So, isn't it strange that the final film, Return of the Jedi, made in 1983 and likely a decade before George even thought of the prophecy of the Choosen One (and please, let me know if I am wrong on that score) is the chapter that sees the fulfillment of the Prophecy. Where the Chosen One finally brings balance to the Force by defeating his master, freeing the galaxy, accepting his fate and merging with the light side of the Force.
It's not a question, merely a thought I had, but it strikes me as very cool that the OT film that benefits most from ROTS is ROTJ. Nice work George.