How does Shakespeare use either magic, illusion, or the imaginary in A Midsummer Night's Dream?
Shakespeare uses magic in A Midsummer Night's Dream to allow characters to act upon revenge as well as to allow characters to create unity. In both cases, magic is used to reveal truth about human nature, even with respect to the fairies, who also have very human-like natures.
Oberon first tells Puck to use the magic flower struck by Cupid's arrow in a way that will allow Oberon to revenge himself on his wife, Titania. Oberon feels jealous because Titania is showering so much affection on a changeling, a changeling that Oberon actually wanted for himself. The juice of the flower will allow anyone sleeping to fall in love with the first living creature he/she sees upon waking. Puck craftily uses his own magic to give the actor Bottom the head of a donkey, symbolic of Bottom's arrogance and stubbornness, then uses the juice of the flower to make Titania fall in love with a man who has the head of a donkey. While Puck's use of magic serves to reveal to Bottom the arrogance and stubbornness of his character while also revealing to Titania her foolish fickleness, Puck's magic also serves to reunite Titania and Oberon by the end of the play. Towards the end of the play, Oberon uses an herb to make the queen "[s]ee as though wast wont to see," meaning to see as she used to see. When she awakens, she feels so enlightened by the experience that she gladly returns to being in love with Oberon.
Puck also uses magic to reveal the true natures of the four Athenian lovers, Hermia, Lysander, Helena, and Demetrius. Puck accidentally makes both Lysander and Demetrius fall in love with Helena using the flower, but his ability to do so reveals that their love for each other is not as strong as they profess it to be, which reveals the true fickleness of human nature. Puck remarks best on what his magic reveals about human nature when he says, "Lord, what fools these mortals be!" (3.2.115). In addition, the love mix-up causes the Athenian characters to quarrel, leading to severed friendships and challenges to duel to the death, further revealing the faults in their human natures.