In the Empire Strikes Back, just as Luke is leaving Degobah to rescue Han and Leia on Cloud City, Yoda and Ben attempt to convince him to stay and finish his training.

YODA: Luke, you must complete the training.

LUKE: Ah, I can't get the vision out of my head. They're my friends I've got help them.

YODA: You must not go.

LUKE: But Han and Leia will die if I don't!

BEN: You don't know that. Even Yoda cannot see their fate.

LUKE: But I can help them! I feel the Force..

BEN: But you cannot control it. This is a dangerous time for you, when you will be tempted by the dark side of the Force.

YODA: Yes, yes! To Obi-wan you listen. The cave.. remember your failure in the cave.

Why did Luke fail during his experience in the cave?

Was it because he was the first to draw his sword upon encountering the image of Vader, with Yoda previously mentioning that Luke wouldn't need his weapons? Or, was it because Luke used anger/fear/hate to strike down Vader's image? Maybe a combination of both, and/or more?

After thought: If Luke didn't take his lightsaber with him, would he still have encountered Vader? If so, is it possible they would have just had a conversation?

Maybe there are other Jedi who have also gone through similar trials, but had had a different, more successful experience, which could provide insight as to what would have happened with Luke should he have taken Yoda's advice and not brought his saber (and, implicitly, a different state of mind)?

  • 1
    I assumed his failure was actually going in and then taking his weapons when he does. It is possible he dipped into dark side emotions though during his time in there.
    – TheLethalCarrot
    Mar 7, 2018 at 16:10
  • 2
    Your afterthought question is answered here.
    – F1Krazy
    Mar 7, 2018 at 16:11