The Merchant of Venice explores the effects of the hatred between Shylock and Antonio when it is measured against Portia's mercy and compassion. Shylock will suffer the ultimate insult when he is forced to convert to Christianity and Antonio will be spared and not have to forfeit "a pound of flesh." It is thanks to Portia that reason returns to Venice as she cannot bear to see her new husband, Bassanio, suffer when he thinks that his dear friend Antonio will die.
The play also looks at the restrictive conditions placed on Portia by her father in her choice of husband and the fortunate outcome when Bassanio chooses the correct casket. There are three caskets, one of gold, one silver and one lead. Each one makes a claim regarding its contents but only one of the caskets contains a picture of Portia and only on selecting correctly can Bassanio marry her. Portia suggests that she has no control over the suitors' decisions but she does try to create the greatest advantage for Bassanio as she is so anxious that he may choose incorrectly.
Music is an important element in the play and, later, in Act V, scene i, Lorenzo will even suggest to Jessica that a man who is not suitably inspired by music should not be trusted because he is "dull as night" (86) and "dark as Erebus" (87).
This has certainly been true for Portia who, in Act III, scene i, insists that music be played while Bassanio makes his decision regarding the caskets. Portia says, in lines 43 to 45, "Let music sound...then if he lose, he makes a swan like end Fading in music..." She goes on to say, "He may win...Then music is...such... as are those dulcet sounds in break of day That creep into the dreaming bridegroom's ear and summon him to marriage" (47-53). Portia believes that the music will calm Bassanio and, with the same resolve but "much more love" (54), he will choose wisely. Bassanio uses the words played to music to help him deliberate more carefully and he comes to a realization of what Portia's father was really saying: Portia's value lies within. Her father did not want her to marry someone who found value more in her possessions and her wealth than in her heart.