Bright Star, would I were stedfast as thou art— (line 1)
In the opening line of the poem, the speaker addresses something non-human, and therefore perhaps part of nature: the "Bright Star," which we know from context means the North Star, or Polaris. From this, would it be fair to say that what the speaker wants is harmony with nature?
Not in lone splendor hung aloft the night (line 2)
But, as have seen, the second line of the poem immediately goes against the impulse of the first line. Instead of union with the Bright Star, and hence with part of nature, the poet says that he doesn't want to be like it. Then again, though, the description of the Star here makes it seem sort of isolated from the rest of nature: it is "lone" and is "hung aloft the night" – i.e., at the highest part of the "night" and therefore above the night, and perhaps above all the rest of nature. So, is the speaker saying that the star is part of nature but is also separate from the rest of nature? Hard to say – looks like we'd better keep reading.
Like nature's patient, sleepless Eremite (line 4)
Well, now the speaker tells us that the star is part of nature – at least in the sense that it is "nature's patient, sleepless Eremite." Still, that's a pretty weird description. After all, an "eremite" (an old-fashioned word for a "hermit") is somebody who lives apart from everyone else, in a desolate or barren area. Once again, it looks like the star is part of nature, but is somehow separate from it.
The moving waters at their priestlike task Of pure ablution round earth's human shores (lines 5-6)
Now we find out what the star is watching. (We were told that the star was "watching" something back in line 3.) Here we get another vision of nature – and it isn't too pretty. Specifically, there seems to be some conflict between humanity and nature. When Keats's speaker talks about the waves washing clean (this is what "ablution" means) the "earth's human shores," it sounds like humans are polluting the shores, which means that humans are the enemies of nature. But then the waves, who are part of nature, give it right back to humans by wiping them off the face of the earth with each new generation. Now it looks like nature itself might not be so great.
Or gazing on the new soft-fallen masque Of snow upon the mountains and the moors— (lines 7-8)
These two lines drive home the idea that nature isn't a basket of roses. These barren scenes, with the barren, blank snow falling on them, show us a nature that is completely indifferent to humanity. In a way, this is kind of a best-case scenario – it isn't as bad as a nature that is actively hostile to humanity, which is what we saw in the image of the waters washing humanity off the shores of the earth. Still, this does drive home the pretty depressing imagery of the first section of the poem: we've got an eternal star that is part of nature but is in the most isolated, lonely part of it, which spends its time staring at other isolated, lonely parts of nature, some of which have the job of wiping the generations of humanity off the face of the earth. At this point, the question all of us should be asking is, "Why the heck would Keats's speaker want to be like the Bright Star – or anything else in nature for that matter?"
No—yet still stedfast, still unchangeable, Pillow'd upon my fair love's ripening breast, To feel for ever its soft swell and fall (lines 9-11)
In the final section of the poem, we see what the speaker means by wanting to be like the star. He wants to live forever the way the star lasts forever, but he wants to spend that eternity with his head resting on his girlfriend's chest. When he describes her chest as "ripening," this shows us that the speaker doesn't think nature is all bad. How do we know this? Because the word "ripening" calls to mind fruit, a part of nature, but a part of nature that is warm and friendly towards humans. So really, what the speaker is saying in this poem is that he likes, first of all, his girlfriend, but also, second of all, the good parts of nature.
What he doesn't like are the aspects of nature that either have nothing to do with humanity or that want to destroy humanity. But there is one further level of complexity. When the speaker says he wishes he and his girlfriend could last as long as the star, is he hoping for something natural? Isn't a human's desire to live as long as a star a desire for something…Supernatural? We sure think so. Now, let's bear in mind that "Supernatural" means, literally, "above nature"; for a human to be "above nature," he or she would first have to triumph over nature. When we think about things this way, it starts to look as if, at the end of the day (OK, at the end of the poem), the speaker's quest to take the good things in nature and preserve them forever puts him into conflict with nature as a whole. Do you think that he realistically expects to be able to defeat nature in this way? Or does he think that nature will win in the end?