This poem is really the poet addressing his remarks to the sun! Donne, ever the fanciful and imaginative poet, takes many impossibilities and uses them in this lyric poem to explain how much he adores his lover. The "busy old foole" (line 1), Donne calls the sun, is peeking through the bedroom window as Donne lays with his beloved. He calls the sun "unruly", which is, of course, the exact opposite of what the sun is. The sun rises and sets regularly, never wavering, in a fixed pattern all the year through. Donne knew that immutable laws covered the motions of heavenly objects, no more so than the sun, so calling such a ruling body "unruly" is strange indeed! He is saying that he wishes the sun was not so regular in his habits.
The sentiment here is that he doesn't want his night with his lover to end. lThis was a standard poetic convention in Elizabethan poetry (compare Romeo and Juliet, Act III scene v), but Donne, being Donne, turns it on his head. Not only does he wish fervently that the morning not come -- he says that the sun is out of order and should not be coming at its appointed time! This kind of poetic arrogance, shown as the lovers' preeminence in importance even over heavenly bodes, is characteristic of Donne.
He tells the sun to go bother other people (as if the sun could shine on some people and not on others! -- again, a diminution of the sun's importance and universality) such as late schoolboys and apprentices and huntsmen rather than the lovers. At the end of the first stanza Donne avers (rather than wishes) that the sun didn't govern the seasons of love (ln 9-10). There is nothing that Donne thinks is more important than love, and all the laws of the universe should be subject to it.
Of course, some of this is meant to be fun. Simply the image of calling the sun a "busy old foole" is meant to bring a smile to the reader's face. But as the poem continues the poet becomes more serious. He tells the sun that his mistress's eyes are more brilliant than his light and he appears to mean it. He tells the sun that all the sweet and wonderful things that he shines on all over the world ("th'India's o spice and Myne" - line 17) are not only pale in comparison to his mistress, but are, in fact, contained in her. She is all the great things on earth.
But Donne doesn't stop there -- "She'is all States, and all Princes I" (line 21) begins the last stanza. "Nothing else is" he states baldly, in a unmetrical line 22. There is nothing on earth that matters other than the lovers and their love -- and in fact all of Creation is contained in them. This poem shows Donne using some of his most extreme metaphors. One wonders if he is always entirely sincere in them, but lines like "Thou sunne art halfe as happy'as we" make the reader think that perhaps Donne is using these wild images and avowals to try to express the enormity of his emotions. It is an unusual love-poem, to say the least