With the writing of Twelfth Night, Shakespeare reached perhaps his highest achievement in sheer comedy, the comedy of entertainment and gaiety without any shadow of unhappiness. From first to last the comic spirit hovers over this play, and both actors and audience join in the gaiety. So skillful is Shakespeare's treatment of his material that audiences forget the plot turns on an improbable set of circumstances, coincidences, and mistaken identities devices in use long before Shakespeare thought of them.
The title of the play symbolizes January 6, the twelfth night after Christmas and the end of the solemn Christmas festivities. For the Puritans in England, the Christmas season was not a time for celebration, but rather a devotional period, filled with somberness and dedication. The twelve days following Christmas were held to be symbolic of motherhood and, therefore, solemn. At the end of this period, the jollification began, and the renewing celebration reached full tempo only during the evening of the twelfth night, which began the season of universal festivity, of masques, pageants, feasts, and traditional sports, marking the end of the holy season. In several senses Shakespeare's Twelfth Night seems to say: "Enough; no more excess." Almost everyone in the play is suffering from an excess of something or other or is about to be converted to something else.
The predominant theme of the play is love. Youth, fantasy, and laughter have made Twelfth Night endure. It is the happiest play Shakespeare wrote, even though a somber strain runs just beneath the surface of the action from beginning to end. The play is loaded with the imagery and vocabulary of love, all in the Italian vogue which was a dominant and popular force on the Elizabethan stage. Popular love cliches are embodied within the play, such as that the woman should be younger than her lover; that man loves more deeply than woman; that true love is jealous.
Theatre-goers remember Twelfth Night for the people they encounter in it, rather than for the working-out of the plot. Their attention centers on the lesser characters in Lady Olivia's household: drunken Sir Toby Belch, foolish Sir Andrew Aguecheek, and the sprightly and devilish Maria. They do no look for dreadful logic, but rather the characters in Twelfth Night verify what audiences know of life. They have all known some pompous Malvolio who thought there would be no more cakes and ale because he was virtuous. Sir Andrew is the quintessence of foolishness. Maria is a little wilder vixen than many play-goers have known, but they recognize the type. Their problems are basic human problems. The lovers' triumph is delayed this time not by parental interference or money or politics, but by the deceits and self deceptions of the characters themselves.
The plot is sheer fantasy: improbable, exotic, romantic. Many of the characters are exaggerated, but no one really objects, and the play's sustained popularity over the centuries stands to refute those realists who insist that only the immediate endures.
The sad note running through the play surfaces with Feste the clown's final song: the players are all happily departed following the grand assemblage of the final act, and Feste, on an empty stage, sings of the wind and the rain, of being a boy and then having to face "man's estate." He reminds us that these overly merry, overly playful, overly sentimental, and overly unrealistic characters have been too concerned with loving, spending, and getting, and that actually the more serious things of life are still there, barely beneath the surface.