For years, I've highlighted the triple structure of Merchant of Venice: Three romances, three plots (casket, bond, ring), three caskets. But then I've forced that triple structure into a dual setting—Belmont and Venice. But the geography of the play is triple too: Shylock's home is a third space. And once one finally sees that (rather obvious) point, things begin snapping into place like popping corn.
The three places form a cosmos: heavenly Belmont, place of music and mysterious lunar beauty; earthly Venice, with its bustle of commerce and deal-making; and the hellish house of Shylock. Both Jessica and Launcelot speak of Shylock's home as an infernal environment. Which means that Lorenzo doesn't just plunder Shylock's house of Egyptian slavery. Lorenzo harrows hell.
Then the three places are locations for three acts of liberation or resurrection: Lorenzo is first, rescuing Jessica and Lorenzo from Shylock's home. Portia is weary and frustrated at the beginning of the play, entombed as she is in the “casket” that her father demanded; Bassanio invades Belmont to raise Portia from her accedia. Because of the way Bassanio rescues Portia, he puts Antonio at risk, and the now-liberated Portia invades the third setting, official Venice, to rescue Antonio from Shylock. Portia comes into Venice not only as the representative of the Beautiful Mount of heaven. She comes as one risen from the dead.
First resurrection: Jessica rescued from Shylock's hell-house. Second resurrection: Portia delivered from the casket and her father's doom. Third and definitive resurrection: Antonio delivered from the knife of the Jew.
Structurally, the play curves back on itself: The first liberation/resurrection is a rescue from Shylock, and so is the last. But both of these deliverances from Shylock depend on the second resurrection. Portia gives Lorenzo and Jessica a place of refuge, and she herself comes disguised to Venice to save Antonio. Theologically, all three rescues are deliverances from the curse of law, resurrections into a new covenant of mercy that seasons justice. It is a very Protestant play.
And then we can match up the environments and their liberations with the three caskets. Shylock's Jewish home is the place of silver, where all is determined by merit. Venice is the golden casket, where men pursue whatever they desire. Moonlit Belmont is lead, ruled by the inscription on the lead casket: “He who chooseth me must risk and hazard all he has.” At the end of the play, the company at Belmont is made up of “leaden” characters, all of whom—Lorenzo, Jessica, Launcelot, Bassanio, Portia, Antonio—have hazarded all.