Contrary to what he told Salerio and Solanio, all of Antonio's money is bound up in a ship abroad. To pay for Benvolio's trip, Antonio suggests that they take out a loan on his credit.
Morocco shows that he is not a pompous man because he does not automatically assume that he deserves Portia. This is his reasoning to pass over the silver casket.
"What's here? the portrait of a blinking idiot,
Presenting me a schedule!..."See in text(Act II - Scene IX)
Arragon opens the casket to find a mirror that reflects his own face. His lines can be played to show his disappointment and self-reflection, or as angry since he truly believed that he would choose the right casket.
The song underlines the basic set up of the casket test: if one chooses a casket based on looks then they probably will love based on looks too. Love based on appearance will die where it was born because it was not true love. Essentially, the song cautions against focusing on something's appearance.
"This ring, good sir?—alas, it is a trifle:..."See in text(Act IV - Scene I)
Remember that this is the ring that Portia gave Bassanio as a symbol of her love and herself. She told him to never part with it as long as he still loved her. However, rather than telling the doctor that this is his wedding ring and that he cannot part with it, Bassanio attempts to devalue the ring. He tells the doctor that it is an unimportant piece of jewelry that the man cannot want.
"Of the duke only,..."See in text(Act IV - Scene I)
Under Venetian law, any foreigner who conspires against the life of a Venetian must give half their assets to their victim and the other half to the state. The fate of their life is then left up to the Duke to decide. Notice that Portia, who earlier triumphed mercy, demonstrates extreme prejudice here. She uses Shylock as an example to all other 'aliens' that try to use Venetian laws for their own benefit. She proves that the law is for rich merchants, not marginalized peoples.
By principal, Shylock means his original bond of three thousand ducats. Defeated, Shylock simply asks for what he originally loaned and abandons his revenge or profit.
Portia invokes dramatic irony with this statement, because Bassanio's wife is in fact "by to hear him make the offer." Bassanio's confession of love makes it all the more urgent that Portia save Antonio and rid Bassanio of his bond to his friend. She must redirect this love towards herself.
Portia defies Bassanio's request to simply subvert the law on Antonio's behalf. She rightly asserts that relieving Antonio of his bond will pave the way for other spend thrifts to get out of their bonds and undermine Venice's entire economic system.
"my hands, my head, my heart:..."See in text(Act IV - Scene I)
Bassanio pledges his whole self to Antonio before the court. This ironically occurs in front of his wife, to whom he should have already pledged his soul and body. Portia must relieve Antonio of his bond so that her husband is not indebted and bound to his friend but rather indebted and bound to her.
The clerk reads the following letter to establish legitimacy for "Balthasar" before he has entered the court. It is unclear whether or not Portia wrote this letter herself or got her cousin Bellario to write it for her. What is interesting is that Portia seems to actually know something about the law. Her knowledge transcends her disguise, which suggests either that Bellario has taught her something about the law or she has privately studied it.
Notice that even though Portia freed Antonio while disguised as the doctor, these two men are still bound to each other. Portia must now use the ring to redirect Bassanio's love and faithfulness onto herself.
