"The Canonization" starts with the poem's speaker wanting to be left alone. He addresses some unnamed person and demands that he (or she) shut their big yapper and leave him in peace—to love. The speaker offers up plenty of other stuff for this other person to make fun of, like his tremors, gray hair, thin wallet, or even his gout.
Then he changes course and tells this person to focus instead on making money, taking a class, studying the arts, or observing folks like lawyers, bishops, or the king's face. Essentially the speaker says, "Do whatever you want, pal, just leave me alone."
Apparently, the person he's addressing is not a good listener, because the speaker keeps at it. He wants to know whom he's ever hurt by being in love. "Life goes on, even though I'm in love," the speaker says, pointing out the soldiers and lawyers still have plenty of business to attend to.
After making this point, the speaker says that the addressed can call him and his lover whatever names he wants to ("speaker and lover, sitting in a tree, k-i-s-s-i-n-g"). It's not the lovers' fault. After all, they were made that way by love. You can call them flies (not nice), but they're also like candles that consume themselves. The speaker also compares himself and his lover to an eagle and a dove, and then says that they're like a phoenix. They rise and die together and, thanks to their love, they're also very mysterious.
Speaking of death—if the speaker and his lover do die, and if they're not fit to be memorialized by a tomb or hearse, then they will just hang out in poetry. If the history books won't have them, they'll live on in sonnets that commemorate them just as well as any fancy urn or elaborate tomb. And he hasn't even gotten to the best part yet. Thanks to these poems (which the speaker calls "hymns"), the lovers will be canonized by everyone as saints.
The speaker's fantasy starts to pick up steam now. The speaker and his lover will look down at everyone and be irritated at how poorly they're loving, compared to how well the lover-saints did it. (We can practically see him high-fiving himself.) He imagines that folks back on Earth will pray to the lover-saints for guidance on how to love properly.