The tone of Merchant is inconsistent, shifting from joyous to serious between—and sometimes during—scenes. The play opens in a melancholy tone, with Antonio in a state of sadness that he cannot pinpoint. Yet moments later, the tone becomes more merry as Bassanio enters and Antonio, awash in love for his friend, promises to help him in any way possible.
The tension between playful and somber tones only becomes heightened as Merchant progresses. Act 3, Scene 1, for example, is one of the most tonally serious moments in the play, as Shylock offers his impassioned "if you prick us" speech. This scene is sandwiched, however, between two much more lighthearted moments: the Prince of Aragon choosing the wrong casket in Act 2, Scene 9, and Bassanio choosing the correct one in Act 3, Scene 2. Portia's tone is cheerful as Aragon flees and she learns of Bassanio's approach; she only becomes more excited when Bassanio wins her hand in marriage—an ecstasy that directly contrasts Shylock's grim tone. Similarly, the tone becomes solemn when Shylock is convicted in Act 4—yet in Act 5, the lovers foster a celebratory tone in the wake of Antonio's salvation.
The dueling tones help contribute to the tragicomic nature of the play, as Merchant undoubtedly holds moments both humorous and bitter. This duality also mirrors that of the characters themselves: each one is capable of great love and great hatred; each can appear one way, yet act another. By employing this dual tone throughout, then, Shakespeare encourages the audience to consider the warring capacities within each character, and indeed within themselves.