And each imagined pinnacle and steep
Of godlike hardship tells me I must die
The "pinnacle and steep" represent the pillars of the Parthenon if I'm not mistaken. But the next line doesn't make sense to me. How can the pillars be of godlike hardship? Also, why are they imagined? I feel like I'm misunderstanding something here...
I have never thought of this line in reference to the Parthenon, and to me that makes no sense. Here's my interpretation:
The way I've always viewed this line is as saying "every high point in hardships that I must face." The poem goes on to say:
Like a sick eagle looking at the sky.
The speaker is ready to die, obviously, because of these godlike hardships. He is like an eagle in that he's tired of flying, sick of having to keep going, since it's such an effort.
The hard times that the speaker is going through are being described as pinnacles, like walking over the crest of a hill. It gets harder and harder ("steeper") because the tension releases at the pinnacle, but he cannot rest because he sees the next pinnacle, the next godlike hardship, coming up.
It's like the light at the end of the tunnel turning out to be another tunnel full of darkness.
You need to read through the enjambed line. It might help to remove the carriage return:
And each imagined pinnacle and steep of godlike hardship tells me I must die
Further... it helps to realize that "steep" is being used here in a non-standard way, largely as a synonym for "pinnacle" (or at least, the steep sides of a mountain leading up to the pinnacle.) It's in there because it rhymes with "sleep". (I'm not crazy about that; it feels forced to me. English just isn't a great language for writing triple rhymes like the ones in the poem. Try Italian.)
So you can read "pinnacle and steep of godlike hardship" is "each difficult thing that has to be done". And in context: he sees the various battles depicted in the marbles, and that puts his imagination in mind of his own eventual death.
Remember that Keats was seeing the marbles in London, rather than on the Parthenon itself. Which gives him a great view of them, at eye level, but they've been removed from context. (Keats never made it to Greece. I don't believe he ever left England. He would surely have known the Parthenon from pictures in books, but I don't know if he would have really connected the marbles to the Parthenon itself.)
