The duke's character is set in his first speech. At the same time that he indulges in the sentimental music, he impetuously grows tired of it and dismisses the musicians. The duke then evokes the metaphor of the sea, which he likens to love. The sea is vast, as is the duke's capacity for love, but the sea is also changeable, unstable, and constantly shifting its mien. At the end of the comedy, the duke, significantly, will shift his love from the Lady Olivia to Viola within a moment; thus we should not be disturbed by this quick change. Feste later compares the duke's love to an opal, a gem which constantly changes its color according to the nature of the light.
When we hear that the Lady Olivia is going to mourn her brother for seven years, her desire to remain "cloistered like a nun" for seven years identifies her as a person of extreme romantic sentimentality, one who is not in touch with the real world; thus, she is a romantic counterpart to Duke Orsino. When the duke hears the news, he is pleased: if she can remain devoted to her brother for so long, it means that she has a constant heart; therefore, she will be constant to a lover forever, when the time comes. The duke then lies down; he goes to his "sweet beds of flowers" (usually an ottoman or lounge) in order to sleep and dream, believing that "love thoughts lie rich when canopied with bowers." In this short opening scene, we have seen the duke restless and enamored of love, tired of love, and finally ready to sleep and dream of love.
