In the second to last stanza, Donne imagines that he and his beloved have died and gone to heaven. They are immortalized in verse on earth because of their great love. It is because they were such models of perfect love that they are canonized, or made saints.
Continuing this thought in the final stanza, Donne's speaker imagines that the people on earth are praying to the lovers. The people ask the two lovers to send to earth a "pattern" of their love. In other words, those still alive want to know how exactly the two built such a perfect love relationship, one better than the world ever knew.
The earth's people, in their request for guidance, note that the lovers made each other into a hermitage, or place of refuge from the rest of society. They mention that the lovers lived together in peace, while they, the earth's current lovers, "rage." The lovers had such a strong love that they held the soul of the entire world reflected in their eyes. Since the lovers showed to perfection what love was, whole "countries, towns, courts" are begging the lovers for their secret.
This poem is tongue-in-cheek, conveying what love feels like when two people are at the dizzying height of it and doing so with the hyperbole or exaggeration that lovers feel. Of course, when one is deeply in love, it seems that one's love is the highest and best the universe has ever seen and that everyone else must be clamoring to have something as perfect.