Disguises Motif
One of the strongest motifs throughout the movie is that of using a disguise in order to gain acceptance to a certain place, or to live undiscovered. The main proponent of this is Viola, who knows that she will not get a job in Olivia's household and so assumes a disguise, that of a young man, in order to work in Orsino's household. It is also a way in which each character who is wearing a disguise takes on their new identity, suggesting that disguise is not just a visual thing but a psychological one as well. An example of this is Feste, who wears a disguise when he speaks to Malvolio in his darkened chamber. Because it is dark, Malvolio will not be able to see him and so what he is wearing should not matter at all, but to Feste it does, because without knowing that he is dressed as the character he is pretending to be he is unable to follow through with the pretense. Malvolio often dresses as a nobleman; he is not a nobleman but he believes that if he is disguised as one then eventually his disguise will become a self-fulfilling prophecy.
Insanity Motif
By all medical definitions none of the characters in Twelfth Night could be said to be genuinely insane; however, there is a fair amount of madness throughout the movie and at best some of the characters are definitely quirky, to say the least. One of the main examples of this is Malvolio, who believes that Olivia loves him. This is such an outlandish proposition that Sir Toby and Andrew view Malvolio as mad for believing it. They then trick him into acting with such peculiarity that it would be hard for him to be thought other than completely insane. Malvolio knows that he is sane and so tells everyone else that they are the insane ones, thereby compounding the impression that he is indeed quite mad.
Antonio is also thought to be insane, because when he sees Viola in her male disguise he assumes that she is Sebastian, and yells at her when she does not recognize him. The general feel of the movie is one that is more of eccentricity than of true madness, but the insanity issue runs throughout and all of the characters seem touched by it to one degree or another.
Olivia Giving Gifts Symbol
Olivia hints that in her opinion it is easier to buy the love of a young man than to win it. This opinion is symbolized by the gifts that she gives to Cesario, and, by default, Sebastian in an effort to win his love. The first gift she gives is via Orsino, the second directly to Sebastian whom she mistakes for Cesario. On both occasions the gifts are beautiful and valuable, and symbolize both her determination to make Cesario love her, and also the fact that the person receiving them is the object of her affections.
Darkness Symbol
Malvolio is locked in a darkened chamber because he is believed to be insane. In order to tease Malvolio and amuse themselves more, Sir Toby and Festes decide to tell him that the room is flooded with glorious light. Of course, because it is a darkened room, Malvolio cannot see this glorious light they are speaking of. This is used to prove that he is insane, because only an insane person would believe that a room that is flooded with light is actually in darkness. In this way, the darkness becomes a symbol of Malvolio's "madness".
Messages Motif
In this movie, the characters like to communicate their love with letters and love tokens rather than by declarations of love. These messages can be used to communicate their love, or to miscommunicate love in order to play a trick on person. For example, Maria's letter to Malvolio that purports to be from Olivia is a deliberate attempt to fool him and humiliate him (and it works). He in turn pens a genuine letter to Olivia explaining that he is imprisoned unjustly and begging for help.
Sometimes the characters in Twelfth Night use other characters as intermediaries in order to communicate; for example, Orsino uses Cesario as a message-bearer to Olivia, who sends Malvolio to Cesario with a declaration of love, a ring and several subsequent love tokens. It is unusual for the characters in this film to make bold statements or to tell another in a face to face situation that they are in love with them; instead, they communicate throughout using messages, letters and love tokens to get the message across instead.
