The first example of duty versus desire comes within the first monolog of the play. Theseus, the Duke of Athens is frustrated that his wedding is four days away. He complains that time is moving too slowly. He is impatient. He desires the nuptial day to arrive so he may wed and then bed Hippolyta. As the Duke, he could of course order the wedding to take place immediately, but he won't. That would go
against court decorum and protocol. There are customs and traditions to follow. Theseus as impatient as he is will do his duty and wait to wed Hippolyta in the proper fashion.
The second example of the duty versus desire theme begins with the entrance of Egeus, a Athenian nobleman who brings a grievance before the Duke. He desires to betroth his daughter, Hermia to Demetrius. Hermia, however loves and desires Lysander. Egeus thinks Lysander has falsely won his daughter's heart and turned her against him. Egeus is Hermia's father and according to Athenian law has the right to pick who she marries. Egeus has a duty to select the best husband for his daughter and he has chosen Demetrius. Hermia and Lysander plead their case but to no avail. Egeus desires his daughter to obey him, follow the law, do her duty, or suffer the consequences. The Duke sympathizes with them. He has no desire to execute Hermia or banish her to a nunnery, but if she disobeys her father he will do his duty and uphold the law. This leaves Lysander and Hermia with no other option but to runaway to where Athenian law cannot find them. In order to fulfill their desire to marry each other together, they reject their duty to obey the law. They confided their plan to Helena, a dear friend of Hermia. Helena should feel a duty to keep her friend's confidence. However, she deeply desires Demetrius and as a result, informs him of the plan in order to win his favor.