The first scene takes place indoors, at the Duke of Illyria's palace. Orsino, the Duke, is musing about the nature his love for Olivia. He is talking to his courtier Curio, and he piles up metaphors, such as the hunt, to explain his feelings of love:
Why, so I do, the noblest that I have:
O, when mine eyes did see Olivia first,(20)
Methought she purg'd the air of pestilence!
That instant was I turn'd into a hart;
And my desires, like fell and cruel hounds,
E'er since pursue me.
The scene ends with the introduction of one of the conflicts of the play. Olivia, the Duke's beloved, is shutting herself up in her palace mourning the loss of her brother. Therefore the lovesick Duke will not have access to her, perhaps for as long seven years.
Scene Two has a different cast of characters, and takes place outdoors on a seacoast of Illyria. Viola, a young lady, has been shipwrecked, and washed up on shore with the captain of the ship and some sailors. She, too, believes that it is possible her brother, Sebastian, was drowned on the same voyage. But the outcome is uncertain -- it is possible Sebastian lived. At this point Viola is a stranger in Illyria, and she is not ready to reveal her true identity. She learns of the cloistered, mourning Countess Olivia, and wishes to become a waiting gentlewoman to her, but she also learns that Olivia is accepting no visitors of any kind. So she decides to conceal her true identity, and enter the household of the Duke in the disguise of a eunuch.
Conceal me what I am, and be my aid
For such disguise as haply shall become
The form of my intent. I'll serve this duke:
Thou shalt present me as an eunuch to him:
This introduces a second source of conflict in the play. Viola, a young woman alone in a strange land, conceals her rank and sex, and pretends to be a eunuch in order to enter the service of the Duke. So the Duke, introduced in the first scene, is isolated from his love (although he has doubts about the veracity of that love even at this point in the play), and will be thrown together, intimately, with an entirely different young woman. A great deal of the comedy of the play is based on the situations introduced in these two scenes.