Themes in Mademoiselle De Maupin by Théophile Gautier include beauty, expectations, and identity.

Beauty

Beauty is the primary love and goal of the main character, d'Albert. It's one of the reasons why he's been unable to pursue women—because he is so focused on beauty, poetry, and art. He's looking for that beauty in other people, but they can't encapsulate it because they are real and not art. Throughout the novel, he speaks about ideal beauty and how even great artists and works of art fall short of it. This is something that he comes to understand by the end of the novel, when he realizes that he is left with Rosette, a real person, who he might love if he does as Madelaine suggests.

Expectations

One of the themes in the novel is expectations. Sometimes a person can have expectations so large that they outstrip reality, and that person will never be completely satisfied. This is the case with d'Albert—and Madelaine knows it. After their night together, she leaves and says:

You believe, perhaps, that I do not love you because I am leaving you. Later you will recognize the truth of the contrary. Had I valued you less, I should have remained, and would have poured out to you the insipid beverage to the dregs. Your love would soon have died of weariness; after a time you would have quite forgotten me . . .

She recognizes that she can only be perfect for him in that one night. That's because she's not a full person. She's only the parts of herself that fulfill his expectations: beautiful, exciting, and passionate. Those expectations would be thwarted if they spent another day together and he saw her as human.

Identity

The theme of identity is best displayed in the character of Theodore, also known as Mademoiselle Madelaine de Maupin. She decided to present herself as a man so that she could know the truth about other men; in other words, their identities are shielded from women because they act falsely around them. As a man, she is able to see who they really are. None of them look closely enough at her to see the truth of her either. Even Rosette, who claims to love Theodore, never realizes that Theodore is actually Madelaine. People's identities are what they choose to share with each other.