In Empire Strikes Back, Luke receives training from Yoda. This consists mostly of extreme piggy-back rides, handstands, and rock levitating. Useful combat skills, no doubt. In the end though, Luke receives a vision of the future courtesy of the Force. In this vision, he sees Han and Leia in pain in a city in the clouds. Based on this info, and armed with his new-found hand-standing skills, he decides to fly off to his friends rescue. Yoda pleads with him to stay and finish his training. Even at the expense of Han and Leia's lives. Then Obi-Wan steps in with an interesting observation. He says,"I don't want to loose you to the Emperor like I did Vader." That comment has always stuck out to me. What did Luke leaving to save his friends have to do with Anakin joining the Dark Side? Along comes Revenge of the Sith and Lucas cleverly weaves these two threads together. Anakin receives a vision of Padme dieing in child birth. This vision is the result of his turn to the Dark Side in the since that she dies as a result of the sequence of events that resulted from his turn. Had he ignored these visions, they would not have come to pass. At the Opera house, Palps mentions the power to prevent death, thus seducing Anakin. Later when Ani learns Palp's true identity, Palps says "Learn the power of the Dark Side. Only then can you save your wife from certain death." This statement planted the seed in Anakin that lead him down the Dark Path. He thought he could save his wife by turning to the Dark Side. Ironically though, Padme was in no real danger. She was only in danger once Anakin joined the Dark Side. So in essence, Palpatine making the above statement was the cause of Anakins visions. Palpatine was indirectly responsible for the visions. Flash forward to ESB. What was the cause of Luke's vision? Han was being tortured. He later said that he wasn't asked any questions. The sole purpose of the torture was to lure Luke to Bespin. Vader knew it would work on Luke because it had worked on him. He has had 23 years at that point to ponder his previous life, and has probably worked out the implications of the visions and Palpatine's part in them. Since the two have evidently not spent much time exploring the power to prevent death, Vader must realise that that whole line was just a con to lure him in. So Ben lost Vader to the Emperor due to his attempts to prevent a vision of his wife's death from being fulfilled, and didn't want to loose Luke due to his attempts to prevent a vision of his friends in pain from being fulfilled. Yoda's advice to father and son is the same. Let go. Death is a natural part of life. I think this was a very clever tie-in on Lucas's part. He has mentioned that theme's repeat and that Anakin and Luke go through very similar experiences, with different outcomes. This is a special case in that Ben's comment in ESB foreshadowed the same thing happening in ROTS. Very clever Mr Lucas. Bravo!