Looking at the words on the page, it’s amazing how close the film stuck to the script. Yet where it deviates, as in the above passage, Kirshner made exactly the right decision.

Yoda tells Luke all that’s in the cave is what he takes with him (possibly the vision of Vader would not have even been armed if Luke hadn’t taken his weapons?), so it’s right that the spectral Vader is initially passive. Luke is first to raise his lightsaber and take an aggressive stance when he sees Vader – the opposite of everything Yoda has been trying to teach him.

(Incidentally, I’d hoped the prequels might’ve revealed this curious “domain of evil” was in fact caused by Yoda himself: could it have been that in the dark times Yoda did something terrible to deal with a Dagobah spy, in order to protect the secret of baby Luke? Perhaps Yoda was not so much in hiding, but bound to that spot through shame and penance, rather like Dumbledore in the Harry Potter series.)