How we cite our quotes: All quotations are from Star Wars: The Empire Strikes Back.
Quote #4
EMPEROR: We have a new enemy—Luke Skywalker. [...] He could destroy us.
VADER: He's just a boy. Obi-Wan can no longer help him.
EMPEROR: The Force is strong with him. The son of Skywalker must not become a Jedi.
The Emperor must not have read many Greek tragedies because if he had he would've known that trying to bypass fate through murder and general villainy always backfires. In addition, Vader's reluctance to accept the implications of the Emperor's prophecy subtly foreshadows the revelation that he is Luke's father.
Quote #5
YODA: It is the future you see.
LUKE: The future? Will they die?
YODA: Difficult to see. Always in motion is the future.
This is important, as it's our first indication that fate isn't exactly—well—fated. Think of it like forecasting a hurricane: It's pretty easy for meteorologists to figure out a range of possible paths for a storm, but it's a lot harder to narrow it down to one.
Quote #6
LUKE: I can't keep the vision out of my head. They're my friends. I've got to help them.
YODA: You must not go!
LUKE: But Han and Leia will die if I don't.
OBI-WAN: You don't know that. Even Yoda cannot see their fate.
Despite Yoda and Obi-Wan's vehement protestations, Luke refuses to abandon his friends to Vader. Once again, this represents Luke actively taking his fate into his own hands, ignoring prophecies and destinies and all of that hogwash and simply focusing on the here and the now. Sounds like a Jedi to us.