In her bower, Titania dotes on Bottom, placing flowers in his hair and kissing his mule-like ears as Bottom orders the other fairies to bring him bags of honey and scratch his head. When Titania asks what he'd like to eat, he asks for some dry oats or a handful of peas, and then they both fall asleep.
Bottom earlier worried that Snug would be mistaken for a real lion. Now Bottom has been put into a magical donkey "costume," and he's starting to act like a donkey. Titania, in love, doesn't notice.
Oberon and Puck enter. Oberon says that he now feels sorry for Titania, especially since she gave him the changeling the night before. He tells Puck to give Bottom back his original head, so that when he wakes he can return to Athens.
Once Oberon has reasserted his authority over Titania, true to his word, he lifts the spell.
Then Oberon drops the juice on Titania's eyelids. She wakes, and though confused how she could have loved an ass, reconciles with Oberon. Titania and Oberon dance together, and Oberon pronounces that on the next night they will dance at Theseus's castle in honor of Duke Theseus's wedding and the weddings of Lysander and Hermia and Demetrius and Helena.
Once humbled, Titania ceases to fight against her husband. Instead, she seems to accept his dominance as rightful. As for Oberon, he looks forward to the end of this comedy he's "written:" the lovers' marriage.
Theseus, Hippolyta, Egeus, and many others enter, about to hunt. But they recognize the sleeping lovers and wake them. Theseus asks Lysander and Demetrius how such rivals came to be sleeping peacefully in the same glade. Lysander isn't sure, but explains his plan to elope with Hermia. Egeus wants Lysander and Hermia punished, but Demetrius says that although he followed Hermia into the woods because he loved her, he now, "by some power," loves Helena (4.1.161). Theseus overrules Egeus, decides that the four lovers will marry at his wedding, and then exits. The lovers comment on the strange dream they all shared the previous night, and follow the duke.
Oberon is the lord of nighttime, the lord of dreams. When dawn comes, Theseus, the upholder of law and reason, is lord. And in the light of day, the lover's passions of the previous night are only vaguely remembered. Yet somehow their irrational dreamlike experiences have exerted an unknown power over them that has solved happily what reason and law could only have solved unhappily.
Bottom wakes, calling out that he should be called when it is his cue to come back onstage. Suddenly he realizes he's not at rehearsal, and thinks that he must have fallen asleep and had an unfathomable and strange dream. He vows to have Quince write down the dream as a song, and to sing it to the Duke at the end of Pyramus and Thisbe.
Bottom, too, thinks his experience was a dream. And just as he saw the incompatibility of love and reason, he now recognizes that to look too deeply into a dream is foolishness. In a dream, as in love, there is nothing to understand.