She's all states, and all princes I, Nothing else is. Princes do but play us; compared to this, All honour's mimic, all wealth alchemy.
We begin the last stanza talking about the lover, which is nice, because, you know, this is a love poem.
Line 21 contains two simple metaphors. First, he equates his lover with all countries. (This is, we hope, not a reference to her weight.) Second, he compares himself to all rulers. There may be some chauvinism here in that he is the ruler or conqueror and she is land to be taken, but it's a pretty common metaphor in 17th-century poetry. Donne's dirtiest poem, "To His Mistress Going to Bed," uses the same imagery (only more explicitly).
Donne uses the linking verb "is" to create his metaphor. Linking verbs (like "is") are direct and blunt, so the metaphor is clear to the audience. To make it even more direct, Donne doesn't even repeat the verb in the second metaphor. The first "is" is applied to both subjects, a technique known as a zeugma (which is not an aerobic dance exercise).
There is another clever poetic technique in play here—chiasmus. A chiasmus is a syntactical reversal: "She is x; y is I." We haven't talked a lot about the form or meter of the poem yet, because, well, it's complicated. But we're sure you noticed that the second line of all three stanzas is really short, only four syllables.
In the previous two stanzas, they set up his metaphysical questions, but in the final stanza this short line makes a bold and blunt proclamation: "Nothing else is." Really, John? Nothing else in the entire world exists except for you and your lover? Ego, much?
Donne's playful egomania keeps right on coming, giving us three examples of the fakeness of the world compared to the reality of himself and his girl. Princes are big fakers, pretending they are as mighty as the narrator. All honor is only simple mimicry. All wealth is alchemy.
Okay, that one might be a little confusing. Alchemy is the ancient search for a method for turning metals into gold. By Donne's time, science had more or less debunked that myth and anyone claiming to have found the secret to alchemy was likely thought of as a con artist.
Line 24 shows us another example of parallelism and zeugma. We have the verb "is" attached to "honour," but it is dropped from the second phrase. This serves to strengthen the connection between the ideas and reinforce to us how fake the rest of the world now is—compared to the speaker's love, that is.
Thou, Sun, art half as happy as we, In that the world's contracted thus; Thine age asks ease, and since thy duties be To warm the world, that's done in warming us.
Line 25 returns us to the apostrophe: Donne is talking to the sun. It also grows more brazen in its claim, saying the sun is "half as happy" as Donne. Usually the sun is seen as pretty, well, sunny. It's mighty bold to say that someone could be twice as happy.
Why are they happy? Line 26 tells us that it's because the whole world has been contracted into their bedroom. When the sun comes up for everyone else, they have to get busy and scurry off to work. But now that the world has collapsed for Donne and his lady, they are free to lounge in bed all day—that's their world.
By this time, Donne acts as if he has made the world actually shrink. He says "thus," as if by claiming the world has contracted in the previous stanza, it is now a plain fact. Obviously, a guy who was a lawyer, poet, and priest had a pretty strong belief in the power of language.
Remember way back in line 1, Donne called the sun a "busy, old fool"? He's returning back to that label here at the end, with his mock-sympathetic tone.
He tells the sun in line 27 that the sun's weak old age demands that the sun take it easy. You know, in case the sun breaks a hip trying to make it over the Pacific Ocean in time for dawn the next day.
Line 27 also brings back the idea of the sun being busy—the sun's "duties" include warming up the whole world.
Donne then becomes a used car salesman: "Look Mr. Sun, you're tired, you're busy, you don't want to run around all day trying to warm up the world. So I'm going to make you a deal—this one time only. You warm up the Mrs. and me right here in this bed and it'll warm up the whole rest of the world for you."
He's using the screwy logic of his metaphor to throw the sun a bone. If the whole world is here in this room, then the sun can linger right there and still do its job.
It may be a stretch to read this into this poem, but Donne really enjoyed making puns with his own name. Line 28 may have a hint of that: "By warming Donne, you're all done!"
Shine here to us, and thou art everywhere; This bed thy center is, these walls thy sphere.
The last two lines of the poem are really about wrapping up the argument and leaving us with a new and bizarre picture of these two lovers in bed.
We began the poem with Donne asking the sun to go bother someone else. Now at the end of the poem, he is commanding/pleading with the sun to stay and only shine on them.
It's as if at the beginning he believed that if the sun could only go away that they could remain there and be happy. But now he realizes that it is the outside world that will come and make demands on them, so he obliterates the rest of the universe and asks the sun to stay with them.
The final line takes us back to the cosmology of Donne's day. The bed is the earth—the center of the universe around which everything else revolves. The outer walls of the bedroom? The sphere of the sun, the farthest boundary that the sun can be. He's collapsed the entire Great Chain of Being—the entire known universe, even—into their one room.
This last line is also another example of making metaphors by using a linking verb ("is") as a zeugma, just in case you wanted to hear us use that word again.