Not light them for themselves; for if our virtues
Did not go forth of us, 'twere all alike
As if we had them not.
Measure for Measure is a play about justice: What it is, what it ought to be, who determines it and why. The play begins as Duke Vincentio of Vienna announces to his advisers that he is going to go away for a short time, placing his deputy Angelo in charge of the city. Angelo, a power-hungry, puritanical scold, pursues the city's dormant fornication laws with vigor, condemning the young Claudio to death for impregnating his lover Juliet before marriage. Claudio's sister Isabella, a novice nun, comes to beg for her brother's life:
ISABELLA: Go to your bosom,
Knock there, and ask your heart what it doth know
That's like my brother's fault. If it confess
A natural guiltiness such as is his,
Let it not sound a thought upon your tongue
Against my brother's life.
ANGELO (aside): She speaks, and 'tis such sense
That my sense breeds with it.
And it is sense: Isabella is saying that if Angelo has ever committed a sin like Claudio's, he must have mercy. She is soon to take orders as a nun, and her vision of mercy is a Christian one, echoing Christ's words: "Let he who is without sin cast the first stone." And yet Isabella's tack is mistaken, as Angelo, "a man whose blood / Is very snow-broth," has never committed such a sin--that is, until he met Isabella. Inflamed with passion, Angelo tells her that he will spare her brother if she surrenders her virginity to him.
The brilliance of these scenes lies in the fact that Angelo seems to be paradoxically turned on not by Isabella's beauty, but by her chastity and rectitude:
...Can it be
That modesty may more betray our sense
Than woman's lightness? Having waste ground enough,
Shall we desire to raze the sanctuary
And pitch our evils there?
Angelo asks in that last sentence, in effect, though Vienna has prostitutes ("waste ground") enough, why do I want so badly to defile a nun ("raze the sanctuary")? Of course, every heterosexual male knows that the forbidden fruit is the most tempting, and modesty more enticing than promiscuity, but Angelo's response to Isabella's virtue is something stranger.
Isabella refuses, and with the help of the Duke, who has not left Vienna but is hanging around in the disguise of a visiting friar so that he might spy on Angelo's rule, they concoct a comic scheme to snare Angelo that involves switching Isabella for Angelo's spurned lover Mariana, and substituting another prisoner's head for Claudio's.
It is easy to read Measure for Measure in a very straightforward (and conservative) way: The Duke and Isabella represent the rectitude of mercy and Angelo represents hypocrisy and severity. But moral authority is undermined in subtle ways in this play. Are we meant to interpret Isabella's stand as virtue, or an indifference to her brother's life not unlike Angelo's puritanism?:
CLAUDIO: Sweet sister, let me live.
What sin you do to save a brother's life,
Nature dispense with the deed so far
That it becomes a virtue.
ISABELLA: O, you beast!
O faithless coward, O dishonest wretch,
Wilt thou be made a man out of my vice?
Is 't not a kind of incest to take life
From thine own sister's shame? What should I think?
Heaven shield my mother played my father fair,
For such a warped slip of wilderness
Ne'er issued from his blood. Take my defiance;
In Isabella's mind, Claudio's fear of death is a perversity, leading to a "kind of incest" and making him a "warped slip of wilderness."
And then there's the Duke, who moves through the play with the air of beneficence. We are invited to view the Duke as a paragon of virtue, but by the end of the play our regard for him becomes unsettled. Why, for instance, does he set out on this mad scheme in the first place? He confides that he does it so that Vienna's "strict statutes and most biting laws" might return under Angelo's authority, but this is exactly what he seeks to undermine in the matter of Isabella and Claudio, without any proof of a change of heart. Once the mistaken-identity games go on a little too long and become a little too complex, we are left to wonder if the Duke doesn't simply enjoy treating the lives of his subjects as a plaything.
Moreover, he disguises himself as a friar, and proceeds to give religious counseling and advice. For example, he instructs Claudio:
Be absolute for death. Either death or life
Shall thereby be the sweeter. Reason thus with life:
If I do lose thee, I do lose a thing
That none but fools would keep. A breath thou art,
Servile to all the skyey influences
That doth this habitation where thou keep'st
Hourly afflict. Merely, thou art death's fool
For him thou labor'st by thy flight to shun,
And yet runn'st toward him still.
Coming from a priest, these words might seem wise, but how do we regard them when we remember that the Friar is actually the Duke, in whom the power of life and death still ultimately rests? Isabella's "Take my defiance; / Die, perish," are chilling enough when they are the words of a powerless woman in an impossibly place; here, the Duke's authority make them both sinister (because he has the power to sentence Claudio to death) and mocking (because he already knows he won't let it happen).
Finally, in the long last scene which occupies the entirety of Act V, the Duke goes about putting everything to rights, spares Claudio, and tells Isabella, "Give me your hand and say you will be mine, / He is my brother too." In most plays this marriage might be fortuitous, but this proposal promises to destroy Isabella's intention to join the convent. She does not protest, nor does she assent--for the remainder of the play, Isabella has no lines. The Duke essentially silences her. Ultimately, are the Duke's actions any different from Angelo's, except that there is no higher authority present in the play to appeal to? It's a stark reminder that justice lies not with the virtuous but with the powerful.