In addition, Shakespeare uses Titania in her potion-induced state to fall in love with Bottom whose head Puck has changed into a Donkey's. It is quite humorous to see her--the Queen of the Pixies--so in love and amorous with this less-than-desirable creature.
One of the themes of this play is that of rebellious daughters. In Shakespeare's time, daughters were expected to do as they were told by the fathers (and other male family members--brothers, uncles, etc.) and then by their husbands. The women were ruled by the men in their lives. The tension caused by this situation as presented by Egeus to Theseus and Hippolyta is relieved by these silly characters and events.
The scenes where the players (Peter Quince and his cohorts) are organizing the play and assigning parts is absolutely hysterical!
"Midsummer" is one of Shakespeare's most comedic comedies. Even when he has sad characters, wandering around the forest seeking love, it is still rather madcap and crazy, particularly with Puck getting involved and getting everything even more confused.
However, there is also a certain amount of intensity with the situations between Hermia and Helena, Lysander and Demetrius. If Shakespeare had spent the entire play focused on these four crazy-in-love people, the play would certainly have been bogged down with intense emotion and hurt feelings. I mean, it is actually quite painful to see Helena chasing after Demetrius, and then later, Lysander chasing after Helena when he's had the love-potion accidentally put into his eyes by Puck. So Shakespeare gave us a wonderful subplot about an acting troupe, trying to come up with a great play to perform at court.
The characters of Bottom and his cronies are so over-the-top laughable that they relieve a great deal of the intense emotion we witness with the four lovers in the forest. Thus we're given comic relief by Bottom, Titania's infatuation over him as an ass, and "The most lamentable comedy and most cruel death of Pyramus and Thisbe" (1.2). How's that for a title? :)
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