“If love be the food of music.. Play on!”- The Duke Orsino
Some characters in Twelfth Night become witless due to romantic attractions. Twelfth Night goes to great lengths to expose the folly of human behavior. It takes shots at love-sickness, mourning, social ambition, and even moral propriety. Throughout the play, foolish behavior is often confused with "madness" or "lunacy." Duke Orsino is clearly only in love with the idea of love itself and views Olivia as just the object of his foolish love. Because Malvolio is blinded by his own self love, his apparent "love" for Olivia is presented as just stupidity. Olivia is sparked by pride while searching for love.
Duke Orsino is in love with the idea of love itself, not Olivia.