O, when mine eyes did see Olivia first,
Methought she purged 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. (1. 1. 22-26)

Olivia, however, busy mourning a recently deceased brother, cannot bother her pretty head with the duke’s importunities. Consequently, the duke needs help to press his suit. Help arrives in the form of a gentlewoman named Viola, who washed onto the shores of Illyria after a shipwreck. Her twin brother, Sebastian, drowned in the shipwreck–or so Viola thinks. To make her way in a world of men, she dons male clothing, calls herself Cesario, and gains employment as the duke’s page. Her first job, the duke tells her, is to persuade Olivia, who lives nearby, to pay attention to him. 

ORSINO:   . . . . . . . . . . . . . . . [T]hine eye  
Hath stay’d upon some favour that it loves:  
Hath it not, boy?  
VIOLA   A little, by your favour. 
ORSINO   What kind of woman is’t?  
VIOLA   Of your complexion.  
ORSINO   She is not worth thee, then. What years, i’ faith?  
VIOLA   About your years, my lord. (2. 4. 23-30) 

What is love? ’tis not hereafter; 
Present mirth hath present laughter; 
What’s to come is still unsure: 
In delay there lies no plenty; 
Then come kiss me, sweet and twenty, 
Youth’s a stuff will not endure. (2. 3. 23) 

Blame not this haste of mine. If you mean well,
Now go with me and with this holy man
Into the chantry2 by: there, before him, 
And underneath that consecrated roof,
Plight me the full assurance of your faith. (4. 3. 25-29)

The action of the play is set in Illyria, in the northwestern Balkans along the Adriatic Coast. Illyrians were ancestors of modern-day Albanians. However, Shakespeare may have intended Illyria as an imaginary country free of time or borders, like Shangri-La, Oz, Avalon, or Prospero's island in The Tempest. 

Themes

True love sees the soul. True love requires recognition of the noble inner qualities of the beloved as well as the outward qualities. Duke Orsino thinks he loves Olivia. But it soon becomes apparent that he loves her primarily for her beauty, not her nobility of soul. In other words, he is infatuated with her looks and charm. However, he gradually falls in love with Viola after her inner qualities emerge while she is disguised as a man. His love for her is not complete until she doffs her disguise and reveals that she is a beautiful woman. Orsino then loves her heart, soul, and body–that is, spiritually and physically. Olivia's love for Sebastian evolves in a similar way. She begins by admiring Sebastian's noble qualities as mirrored by his twin sister Viola, disguised as the male messenger Cesario. But her love is incomplete until Sebastian arrives with the same noble qualities of Viola–but in a male body. 
Love (brotherly and romantic) is foolish at times. For example, Olivia goes to ridiculous lengths to mourn her dead brother, then falls in love with Viola disguised as a man. Pompous Malvolio, meanwhile, wears yellow stockings with crossed garters to woo Olivia. 
Love vexes and presents pitfalls. Orsino, Viola, and Olivia, undergo distress and suffer setbacks of one kind or another before being united with his or her beloved. Malvolio, of course, falls into a pitfall and never gets out.
Love ultimately triumphs. Despite all the obstacles they face, people in love eventually unite through persistence.
Appearances and first impressions can be deceiving. Outward appearances and first impressions mislead the main characters in one way or another–until the truth surfaces in Act V. 
Carpe diem (seize the day). Feste chides his employer, Olivia, for continuing to mourn for her brother long after he is dead. He realizes that one of the main purposes of life is to live. In a song he sings for Sir Toby Belch and Sir Andrew Aguecheek, he sums up his philosophy:

What is love? 'tis not hereafter; 
Present mirth hath present laughter; 
What's to come is still unsure: 
In delay there lies no plenty; 
Then come kiss me, sweet and twenty, 
Youth's a stuff will not endure. (2. 3. 23)

Priggish Malvolio becomes the brunt of a practical joke after he attempts to interdict the merriment of Feste, Aguecheek, and Sir Toby Belch. It appears that Shakespeare intended to use Malvolio to satirize the somber spirit of Puritanism during the Elizabethan era. In fact, the characters in the play openly refer to him as a Puritan, as in this dialogue in Act II, Scene III:  

MARIA   Marry, sir, sometimes he is a kind of Puritan.  
SIR ANDREW      O, if I thought that I'ld beat him like a dog!  
SIR TOBY BELCH  What, for being a Puritan? thy exquisite reason, dear knight?  
SIR ANDREW      I have no exquisite reason for't, but I have reason good enough.  
MARIA   The devil a Puritan that he is, or any thing constantly,  
but a time-pleaser; an affectioned ass, that cons state without book 
and utters it by great swarths: the best persuaded of himself, 
so crammed, as he thinks, with excellencies, that it is his grounds 
of faith that all that look on him love him; and on that vice in him 
will my revenge find notable cause to work. (Lines 151-160)

Ingredients of the Comedy 

Shakespeare mixes Twelfth Night with a potpourri of ingredients to achieve his comic effect–a set of twins, some situation comedy, a dash of dramatic irony, a dollop of romance, three boisterous merrymakers, and a puritanical sourpuss. Following is an explanation of how Shakespeare uses these ingredients:

The Twins

Viola and her brother, Sebastian, are twins–born about an hour apart–who survive a shipwreck. When they cannot find each other, each thinks the other may be dead. Then they go their separate ways, establishing two story lines that undergird plot surprises later involving mistaken identities. 

Situation Comedy

Viola complicates the plot after she disguises herself as a young man, calling herself Cesario, and obtains employment as a page with Duke Orsino. When she acts as a go-between to help the duke woo Olivia, Viola begins to fall in love with the duke while Olivia begins to fall in love with Viola, thinking “him” a handsome young fellow. Thus, the play takes on the characteristics of a modern situation comedy. Realizing her predicament, Viola says that

          my master loves her [Olivia] dearly;
And I, poor monster, fond as much on him;
And she, mistaken, seems to dote on me.
What will become of this? As I am man,
My state is desperate for my master's love;
As I am woman,–now alas the day!–
What thriftless sighs shall poor Olivia breathe!
O time! thou must untangle this, not I;
It is too hard a knot for me to untie! (2. 2. 24-32)

Dramatic irony occurs when a character in a play, novel, film, or any other work is unaware of plot developments or background information known to the audience. In Twelfth Night, Shakespeare uses dramatic irony numerous times. A memorable example it begins with Line 22 in Act I, Scene II, when Duke Orsino notices that Viola (disguised as Cesario) seems preoccupied. It is, of course, budding love for the duke that preoccupies her. Although she comes close to giving away her feelings, Orsino remains dumb to the cause of her distraction. Here is the dialogue in which they engage: 

DUKE ORSINO...My life upon't, young though thou art, thine eye 
Hath stay'd upon some favour that it loves: 
Hath it not, boy? 
VIOLA...A little, by your favour. 
DUKE ORSINO...What kind of woman is't? 
VIOLA...Of your complexion. 
DUKE ORSINO...She is not worth thee, then. What years, i' faith? 
VIOLA...About your years, my lord. (2. 4. 23-30)

Cesario, by the roses of the spring, 
By maidhood, honour, truth and every thing, 
I love thee so, that, maugre3 all thy pride, .
Nor wit nor reason can my passion hide. 
Do not extort thy reasons from this clause, 
For that I woo, thou therefore hast no cause, 
But rather reason thus with reason fetter, 
Love sought is good, but given unsought better. (3. 1. 115-122)

The love bug bites not only Viola, Orsino, and Olivia but also Viola’s brother, Sebastian, along with Sir Toby Belch and Maria–and even priggish Malvolio. However, Malvolio is more in love with himself than with Olivia. 

The Merrymakers and Malvolio

The adventures of Sir Toby Belch, Sir Andrew Aguecheek, and Feste the Fool provide rousing comic interludes between the other parts of the play. Especially delightful is the trick the threesome play on dour Malvolio–with the help of Maria–in which they convince him that Viola loves him. Malvolio helps make the play work; he is the gray cloud that blocks the sunlight and evokes cheers when he passes.

Allusions

As in most of his plays, Shakespeare uses allusions (references to a mythical, biblical, or historical person or event) to enrich his figures of speech. Twelfth Night provides an excellent opportunity for instructors to teach allusions, for the play abounds in references to mythical, biblical, and historical events. Following are examples:   
 

Allusion	Context and Explanation
..	..
Like Arion on the dolphin's back,	Arion: Greek musician rescued by a dolphin after sailors stole his
I saw him hold acquaintance with the waves	money and ordered him to jump overboard.
So long as I could see (1. 2. 17-19).	In this simile, the captain compares Viola's brother, Sebastian
	to the mythical Arion. The passage also contains personification–
	the waves become Sebastian's acquaintance–and alliteration of
	the words saw, so, and see.
Diana's lip	Diana: Roman name for Artemis, Virgin goddess of the moon and
Is not more smooth and rubious; thy small pipe	the hunt in Greek mythology.
Is as the maiden's organ, shrill and sound,	Shakespeare again uses a simile. (Although like or than is not
And all is semblative a woman's part(1. 4. 31-34).	expressed, it is understood: Diana's lip is not more smooth
	and rubious [than yours] or Your lip is as smooth and as
	rubious as Diana's.) In the simile, Duke Orsino compares Viola,
	disguised as a male, to Diana. The passage also contains a
	metaphor, which compares Viola's voice to a pipe, and another
	simile, which compares the pipe (voice) to a woman's voice
	(organ). Of course, Viola is a woman, but the Duke thinks she
	is a young male because of her disguise.
I had as lief be a Brownist as a politician. (3. 2. 14)	Brownist: Follower of Robert Browne, a Puritan extremist who
	advocated separation from the Church of England and demanded
	freedom from government interference. He was jailed more than
	30 times for his activities.
	In this line, Sir Andrew Aguecheek, who has designs on Viola,
	is responding to a suggestion that he use either valor or political
	skill to win Viola. His sarcastic remark, a form of verbal irony
	with the allusion to Puritan extremism, makes it clear he prefers
	being valorous to being political.
Why should I not, had I the heart to do it,	Egyptian thief: Thyamis, an Egyptian robber who stood ready to
Like to the Egyptian thief at the point of death,	kill his captive, Chariclea, to prevent enemies from taking her.
Kill what I love? (5. 1. 100-102)	Here, Duke Orsino compares himself with Thyamis and Olivia
..–Duke Orsino, Act V, Scene I, Line 120-122	with Chariclea when Olivia rejects him.

Imagery of Love

Because the plot of Twelfth Night centers on the theme of love, so does much of its imagery. But, of course, as Shakespeare has demonstrated in other plays–tragedies and histories as well as comedies–it is not always easy to discover whom one truly loves, let alone woo him or her successfully. Moreover, although love is pleasurable, it is often painfully pleasurable. In addition, although the object of one’s affection may be within earshot, he or she may be a world away emotionally. In Twelfth Night, Shakespeare’s imagery chronicles the blissful anguish of love, the ways which love conceals or reveals itself, and the giddy joy of capturing it heart and soul. Following are examples of imagery on the theme of love:

The Painful Pleasure of Love

If music be the food of love, play on; 
Give me excess of it, that, surfeiting, 
The appetite may sicken, and so die. (1. 1. 3-5)
Duke Orsino speaks a paradox in saying that the sustainer of love, music, may become the destroyer of love.
 
 Come away, come away, death, 
 And in sad cypress let me be laid; 
 Fly away, fly away breath; 
 I am slain by a fair cruel maid. (2. 4. 55)
 Feste speaks a personification and an apostrophe when he addresses death, an alliteration with sad cypress, and an oxymoron with fair cruel maid. 

If ever thou shalt love, 
In the sweet pangs of it remember me; 
For such as I am all true lovers are, 
Unstaid and skittish in all motions else, 
Save in the constant image of the creature 
That is beloved. (2. 4. 14-19)
Duke Orsino uses an oxymoron (sweet pangs) when speaking of love. 

The Transparency of the Emotions
 
A murderous guilt shows not itself more soon 
Than love that would seem hid: love’s night is noon. (3. 1. 114-115)
Olivia speaks a paradox, saying that trying to hide feelings of love succeeds only in revealing them.
                  
She never told her love, 
But let concealment, like a worm i’ the bud, 
Feed on her damask cheek: she pined in thought, 
And with a green and yellow melancholy 
She sat like patience on a monument, 
Smiling at grief. Was not this love indeed? (2. 4. 96-101)
In a paradox, Viola says concealment of love reveals it. In similes, she compares concealment to a worm and patience to a monument. In a metaphor, she compares melancholy to an object that is green and yellow.
 
Love Poem Foreshadowing a Happy Ending
 
O mistress mine! where are you roaming?
O! stay and hear; your true love’s coming, 
That can sing both high and low: 
Trip no further, pretty sweeting; 
Journeys end in lovers meeting, 
Every wise man’s son doth know. (2. 3. 20)
Feste sings this poem, which has a rhyme scheme of aabccb. Note: roaming and coming constitute eye rhyme but not true rhyme. 

The names of several characters appear to be metaphors or symbols. For example, Malvolio means bad desires or bad intentions. (The prefix Mal means bad or evil, as in malicious; volio means I wish or I desire, from the Latin volo.) Sir Toby Belch is a mug of beer given to burping. (A toby is a jug or mug resembling a fat man; a belch is an expulsion of gas from the mouth.) Feste is jolly, festive, celebrating the joy of the moment. Viola, who disguises herself as a man, is the name of a musical instrument with a deeper tone than a violin's–in other words, a more masculine tone. One may fairly speculate that Sebastian is named after Saint Sebastian, who was ordered killed because he was Christian. However, after archers pincushioned him with arrows and abandoned him, he remained alive and was nursed back to health. In Twelfth Night, Sebastian is presumed dead after a shipwreck but, like Saint Sebastian, survives. The name Aguecheek is a combination of ague, meaning fever, and cheek, meaning the fleshy side of the face. Thus, Sir Andrew Aguecheek is wine-drinking, red-cheeked fellow. Olivia may represent the olive tree, famous for its exquisite beauty.  

Climax

The climax of a play or another narrative work, such as a short story or a novel, can be defined as (1) the turning point at which the conflict begins to resolve itself for better or worse, or as (2) the final and most exciting event in a series of events. The climax of Twelfth Night occurs, according to the first definition, when Olivia claims to love Cesario (Olivia). According to the second definition, the climax occurs in the final act when twins Viola and Sebastian establish their true identities.  

Key Dates

Date Written: 1601. 
First Performance: Probably January or February of 1602. It is possible that the play was staged on January 6, the Twelfth Night of the Christmas season, as part of events celebrating the holiday season. This debut date would explain the title.  
Publication: 1623 as part of the First Folio.   

Source

The probable main source of Twelfth Night is Apolonious and Silla, by Barnabie Riche. The story was included in Riche's Farewell to the Military Profession, published in 1581. Riche based his work on a story in Matteo Bandello's Novelle. The latter was based on an anonymous Sienese comedy, Gl'Ingannati (The Deceived), published in 1537.    

Type of Work

Twelfth Night is a comedy written in the festive spirit of the Twelfth Night of the Christmas season, January 6, as part of events celebrating the holiday season. 
Number of Words in Complete Public-Domain Text: 21,467. 
Individual Copies for Schools: Folger Shakespeare Library Edition (Low Cost)

Shakespeare's Use of Disguises 

Time and again, Shakespeare disguises women as men to further a plot. For example, In All's Well That Ends Well, Helena wears the attire of a pilgrim to get close to Bertram. In Cymbeline, Imogen becomes a page boy to win back Posthumous. Julia also becomes a page boy in The Two Gentlemen of Verona, as does Viola in Twelfth Night. In The Merchant of Venice, Portia disguises herself as a male judge to save the friend of her lover in a court of law. Rosalind, in As You Like It, dons the garb of a man to become a shepherd as she seeks out her love, Orlando. In each of these plays, the women disguised as men eventually reveal their true female identities All of this could have been quite confusing to playgoers in Shakespeare's day, for only men played women's roles. Thus, in the above-mentioned plays, men played women disguised as men who at some point doffed their male identities to reveal themselves as females.
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Study Questions and Essay Topics
   
1. Viola dons a male disguise to get a job. Do people today sometimes disguise themselves–figuratively or literally–to gain employment? ....What other extra measures do women sometimes take to succeed in male-dominated workplaces? 
2. Who is the most practical, level-headed character in the play? Explain your answer. 
3. Shakespeare pokes fun at the Puritans, represented by the character Malvolio. Who were the Puritans? What were their beliefs and ....their goals? When a person uses the word puritanical today, what does he or she usually mean? 
4. In what ways does Twelfth Night resemble a modern TV situation comedy? In what ways is it unlike a TV comedy? 
5. Write an essay describing how dramatic irony enhances the comic situations in Twelfth Night. Dramatic irony occurs when a character ....does not see or understand what is obvious to the audience.

1. Coziers’ catches: Alcohol-induced singing.
2. Chantry: Chapel.
3. Maugre: Malgré, French for in spite of.