What did Yoda mean when he said "Strong am I in the Force, but not that strong"?

Question

In Return of the Jedi, as Yoda lies dying, he speaks to to Luke:

YODA
Soon will I rest. Yes, forever sleep. Earned it, I have.

Yoda sits himself on his bed, with great effort.

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.

I'm confused as to exactly what he meant by the bold text, mainly because of Yoda's, shall we say, unique speech constructs.

My confusion hinges on exactly what he is referring to the second time he says "strong". I can interpret this two different ways:

1. He means "I am strong in the Force, but I am not strong enough in the Force to prevent my own natural death."
2. He means "I am strong in the Force, but my body is not physically strong."

The way he pronounces it in the movie (putting the emphasis on "strong" rather than on "that") makes it sound overwhelmingly like it is his intention to convey the second meaning, but this seems very, very uncharacteristic for Yoda, as the whole point of his character is to demonstrate that the Force transcends physicality and that what we can accomplish is not constrained by our material bodies. However, he seems fully comfortable with his own death, implying that he might not be trying to use his force abilities to prolong his life, which would mean that his longevity would be dictated solely by his physical condition, which was "not that strong." This muddles the picture to the point where I am utterly confused.

Does anyone have any information regarding this that might clarify the quote? Am I just hearing it wrong when I think it sounds like he is referring to his physical strength? Is there perhaps a third interpretation I have missed?

Answer 1

Yoda is referring to the first interpretation you offer. I admit, upon looking at the quote written down it is somewhat ambiguous, but in the context in which Yoda made that comment he was clearly referring to his inability to achieve immortality. The latter interpretation is only possible due to Yoda's strange speech pattern, not the intended inference.

Answer 2

It's also relevant to note that Yoda quite likely has already used the force to sustain his life somewhat longer than intended--he's quite sick when Luke shows up in 'Jedi', and let's entertain the idea it's not just drama that he JUST HAPPENS to die exactly when Luke returns, going from walking-around-with-moderate-difficulty healthy to holding on to the last moment when he gives Luke the final piece of information necessary to the greater struggle (as gradually weakens in the interim, repeating some of his important Jedi-pep-talk on his death bed as his speech slows): 'Do not underestimate the powers...of the Emperor. Or suffer your father's fate, you will. Luke. Luuuuuuuuke...(fading)...there is...(gathers strength)...there is...another...Sky-wal-ker...(dies, body disappears, JW scoring swells)

My guess is: he's foreseen this moment and has used his connection to the force ('life creates it, makes it grow' / 'It's an energy field that connects all living things. It surrounds us, and penetrates us: it binds the universe together [-Kenobi, Ep IV] to sustain himself until this final, necessary, predicted chat with Luke.

There's also another hint, given after he's been on his feet, even being slightly sassy, just after he gets into bed to continue his final conversation with Luke--but before he noticeably weakens much, aside from the need to get off his feet. 'Rest. Yes, rest. Forever sleep.' That's what prompts Luke to rhetorically spout that 'you can't die [on me! Now, of all times, for chrissake!]' the line that prompts Yoda's own line that we are discussing here. He knows exactly what's coming, and as you watch the scene, is tired and weakening rapidly, but seems to concentrate and partly rally, after that moment, in order to give Luke his final cosmic talk and task, before, having said 'Skywalker,' letting himself fade away. This is a man (as it were) who cannot prevent his own death, but who has been strong enough, in the force, not his body so much, to push through and hold out just long enough to do his own necessary task, telling Luke what is required.