In Act IV, Scene 1 of The Merchant of Venice, Shakespeare prominently uses the dramatic device of contrasts to starkly draw the picture of the horror and bassness of Shylock's intended action. Shylock starts a series of contrasts with his speech in which he says:

Some men there are love not a gaping pig;
Some, that are mad if they behold a cat;
And others, when the bagpipe sings i' the nose, . . .

Antonio takes up the device of contrasts in his speech to Bassanio begging him not to try to reason with Shylock. Antonio's contrasts start:

You may as well go stand upon the beach
And bid the main flood bate his usual height;
You may as well use question with the wolf
Why he hath made the ewe bleat for the lamb; . .

Antonio takes up the device of contrasts again in his rejoinder to the Duke in his speech that starts: "You have among you many a purchased slave, / Which, like your asses and your dogs and mules,  . . .."

Shakespeare uses another dramatic device, that of surprise when he introduces the surprise presence of Belthasar, who is Portia in disguise. Surprise is a dramatic device used to provide an unexpected twist in the plot. Contrast is a dramatic device used to arouse strong emotions by painting opposition that gives emphasis or clarity.