But Portia has no mind to sit at home and do nothing while her husband’s friend is in danger of his life.  As soon as Bassanio has gone, she gives her house into the keeping of Lorenzo and sets out for Venice.  From her cousin, the great lawyer Bellario, she borrows lawyer’s robes for herself, and those of a lawyer’s clerk for Nerissa.  And thus disguised, they reach Venice safely.

This part of the story has brought us to the fourth act of the play, and when the curtain rises on this act we see the Court of Justice in Venice.  The Duke and all his courtiers are present, the prisoner Antonio, with Bassanio, and many others of his friends.  Shylock is called in.  The Duke tries to soften the Jew’s heart and make him turn to mercy, in vain.  Bassanio also tries in vain, and still Bellario, to whom the Duke has sent for aid, comes not.

At this moment Nerissa, dressed as a lawyer’s clerk, enters, bearing a letter.  The letter is from Bellario recommending a young lawyer named Balthazar to plead Antonio’s cause.  This is, of course, none other than Portia.  She is admitted, and at once begins the case.  “You stand within his danger, do you not?” she says to Antonio.

“ANTONIO.  I do.

PORTIA.  Then must the Jew be merciful.

SHYLOCK.  On what compulsion must I?  Tell me that.

PORTIA.  The quality of mercy is not strained;
    It droppeth, as the gentle rain from heaven
    Upon the place beneath; it is twice blessed;
    It blesseth him that gives, and him that takes: 
    ’Tis mightiest in the mightiest; it becomes
    The throned monarch better than his crown;
    His scepter shows the force of temporal power,
    The attribute to awe and majesty,
    Wherein doth sit the dread and fear of kings;
    But mercy is above this sceptr’d sway,
    It is enthroned in the hearts of kings,
    It is an attribute to God himself;
    And earthly power doth then show likest God’s
    When mercy seasons justice.  Therefore, Jew,
    Though justice be thy plea, consider this—­
    That in the course of justice, none of us
    Shall see salvation:  we do pray for mercy;
    And that same prayer doth teach us all to render
    The deeds of mercy.  I have spoke thus much,
    To mitigate the justice of thy plea;
    Which if thou follow, this strict court of Venice
    Must needs give sentence ’gainst the merchant there.

SHYLOCK.  My deeds upon my head!  I crave the law,
    The penalty and forfeit of my bond.

PORTIA.  Is he not able to discharge the money?

BASSANIO.  Yes, here I tender it for him in the court;
    Yea, twice the sum:  if that will not suffice,
    I will be bound to pay it ten times o’er,
    On forfeit of my hands, my head, my heart: 
    If this will not suffice, it must appear
    That malice bears down truth.  And I beseech you
    Wrest once the law to your authority: 
    To do a great right, do a little wrong;
    And curb this cruel devil of his will.