In Belmont, Portia begs Bassanio to delay before making his choice among the caskets. If he chooses incorrectly, she will lose the pleasure of his company. Though she refuses to break the terms of her father's riddle of the caskets, she confesses that if it were up to her she would give herself to him entirely. Bassanio, though, is tortured by the uncertainty of waiting, and convinces her to let him try the riddle.
Portia is so strictly bound by the legal rules in her father's will, that she must abide by whatever happens even if it means that she loses the man she loves.
Portia instructs that music should be played so that, if Bassanio chooses incorrectly, he will at least make a "swan like end." The song commences: "Tell me where is Fancy bred, / or in the heart, or in the head..." Bassanio stands before the caskets debating his choice for some time. First he rejects gold: "hard food for Midas, I will none of thee" (3.2.102); then silver, "pale and common drudge 'tween man and man" (3.2.103–4). Finally, Bassanio chooses lead.
The last word of every line in the song rhymes with "lead." Portia has found a way to clue Bassanio in to the right answer without breaking the rules of the riddle of the caskets. Whether Bassanio picks up on the clue is unclear, but this is not the last time that Portia displays a keen legal mind.
Bassanio opens the lead casket. Inside, he finds a painting of Portia and a poem praising the wisdom of his choice. Bassanio turns to Portia, insisting that he must also have her consent, if they are to marry. Portia reassures him: "Myself, and what is mine, to you and yours / Is now converted" (3.2.166–7). As a symbol confirming her love, she gives him a ring, with which he must promise never to part. Bassanio is almost too happy to speak: "Only my blood," he tells her, "speaks to you in my veins" (3.2.176).
Just as Jessica converted to Christianity for Lorenzo, Portia describes her entire self, and all her wealth and belongings, as converted to Bassanio. Love is connected both to transformation and economic ownership. With his metaphor of speaking to Portia with the blood in his veins, Bassanio connects love to the description of humans as animals that Shylock used to define human beings in 3.1.
Nerissa and Gratiano, who have been watching, express their joy. Gratiano, seizing the moment, asks Bassanio for permission to marry, confessing that he has already fallen in love with Nerissa. Nerissa confirms that she loves Gratiano as well. Bassanio declares that the four of them will share a wedding.
Along with Jessica and Lorenzo, Gratiano and Nerissa provide a second parallel to the love between Bassanio and Portia. In this case, love comes off looking rather superficial—or, at the very least, abrupt.
Lorenzo and Jessica enter with Salerio. Bassanio and Portia welcome them. Salerio explains that he is carrying a letter from Antonio for Bassanio. Gratiano and Nerissa continue to flirt and joke cluelessly as Bassanio begins reading.
The ugly reality of Shylock's revenge plot—and Bassanio's debt to Antonio—disrupt the idyllic love scene.
Bassanio gets increasingly upset as he reads the letter. He tells Portia about the money he allowed Antonio to borrow from Shylock and of Antonio's lost ships. Salerio curses Shylock's brutality: "Never did I know a creature that did bear the shape of man so keen and greedy to confound a man" (3.2.274–5)," and comments that Shylock has been begging the Duke to give him justice. Jessica pipes in that when she was with her father she heard him say that "he would rather have Antonio's flesh / than twenty times the value of the sum / that he did owe him." All agree that unless "law, authority, and power" (3.2.288) can find a way to deny Shylock his vengeful desire, Antonio is in trouble.
For the first time, everyone, including Bassanio, seems to process the horrible reality of the revenge plot. Salerio, speaking for the other Venetians, condemns Shylock for his bestial quality: because he wants to do something so cruel, they think he's not even human, but only a "creature." The abuse that Christians typically hurl at the Jews, however, does not occur to them as bestial at all. Jessica's comment implies that Shylock is consumed by the desire for revenge.
Portia asks Bassanio whether Antonio is a dear friend. When Bassanio affirms that he is, Portia offers to pay the three thousand ducats that he owes 20 times over. She then asks to see the letter.
Like Antonio before her, Portia shows generosity toward Bassanio, out of love. However, like Shylock, she also gives Bassanio a price, as if he were an animal.
Bassanio reads the text aloud. In it, Antonio confesses to that there is no chance that he will survive Shylock's extracting of the pound of flesh. However, Antonio insists tells that all debts between himself and Bassanio are cleared. He has only one request: to see Bassanio before he dies. Bassanio hastily prepares to depart.
Antonio's letter confirms the depth and intensity of his feelings for Bassanio. His last request—to see Bassanio before he dies—sounds like that of a lover, rather than that of a friend.