Some of the themes in Oliver Goldsmith's 1773 play "She Stoops to Conquer" include class bias, the concept that there is hope for humanity despite its flaws, and the idea that love ignores social boundaries. "She Stoops to Conquer" is a comedy about a well-born young woman who pretends to be of a lower class to put at ease the man she hopes to marry.
Because the plot of "She Stoops to Conquer" revolves around the differences between the classes, it is not surprising that class bias resonates as a theme. Marlow is comfortable with but disdainful toward lower-class women, yet he is very shy around upper-class women. His reactions, based on his presuppositions regarding how people of a different class think and behave, reflect the theme of class bias, as does Mrs. Hardcastle's insistence on valuing people based on what they own.
As Kate crosses social boundaries to try to conquer Marlow, the theme of love ignoring social boundaries is well expressed. This theme was very appropriate for 18th-century England, in which class boundaries were rigid. This theme is, however, turned on its head when Marlow learns that since Kate was in disguise, he has actually not crossed social boundaries at all.
Even though Kate sees social boundaries clearly, as opposed to Marlow's strong biases, her ability to look past them and appreciate Marlow's good qualities speaks to the theme that there is hope for humanity and for love, regardless of individuals' flaws. Mr. and Mrs. Hardcastle's ability to love each other despite their faults also reflects this theme.