Three characters are introduced, including two of the three major ones: the duke and Angelo. Scene 1 establishes the structure within which the action of the play will go forward. A wise monarch is leaving the city in the charge of a younger, less experienced man who is known for his virtue and worth, but who, by his own account, is untested.
Escalus, an elderly lord, stands high in the esteem of his duke. The nature of the commission that he is given to carry out in the duke's absence is unclear, due apparently to a missing bit of text in the duke's first speech.
Angelo is highly praised by both the duke and Escalus. This praise and the man's own modest reluctance to take over the city's highest post combine to portray Angelo as a virtuous and capable man who will work for the good of the people. In a frequently quoted speech (I. i. 30-41), the duke compares him to a torch that is lighted not for itself but for the light it can give to those around it.
The duke is characterized by his own speeches as a man of intelligence and sensitivity who has the good of his people at heart. He announces that he will leave privately: "I love the people, / But do not like to stage me to their eyes" (I. i. 68-69). The speech expressing a respect for the people but a dislike for mob attention was probably added for the benefit of King James, at whose court the play was first performed. James was well-known for his dislike of a throng.
In deputizing Angelo, the duke tells him that he has the scope to "enforce or qualify the laws / As to your soul seems good" (I. i. 66-67). That the deputy has the authority to qualify or modify the law and does not exercise it is one of the sources of the play's tragedy.
