[Dialogue from Return of the Jedi (1983)]
YODA : Hmm. That face you make. Look I so old to young eyes?
LUKE: No... of course not.
YODA : I do, yes, I do! Sick have I become. Old and weak. When nine hundred years old you reach, look as good you will not. Hmm?
Soon will I rest. Yes, forever sleep. Earned it, I have.
LUKE: Master Yoda, you can't die.
YODA : Strong am I with the Force... but not that strong! Twilight is upon me and soon night must fall. That is the way of things ... the way of the Force.
LUKE: But I need your help. I've come back to complete the training.
YODA : No more training do you require. Already know you that which you need.
LUKE: Then I am a Jedi?
YODA : Ohhh. Not yet. One thing remains: Vader. You must confront Vader. Then,
only then, a Jedi will you be. And confront him you will.
LUKE: Master Yoda... is Darth Vader my father?
YODA: Mmm... rest I need. Yes... rest.