One motif of Measure for Measure shows itself when characters use other people, or ideas of people, to achieve goals.
Some examples:
Angelo uses the idea of himself as a strictly pious ruler to demand sex from Isabella.
Claudio is willing to use Isabella to save his own life.
The duke uses the image of a friar, a virtuous and trustworthy person, to spy on others.
Isabella uses Mariana to save her virginity.
The duke attempts to use Barnardine to save Claudio; he then uses a dead pirate instead.
This motif ties in with the theme of the play, illustrated in the title. Obviously the characters are forced to measure the value of their own virginity, happiness, or social position in terms of each other. In addition, the characters are forced to measure each other. Shakespeare uses this tactic to explore how and why we judge others’ actions and value certain people over others when it comes to achieving our personal goals.