How does Jane Austen use Lady Catherine to highlight the theme of prejudice?
Lady Catherine's wealth and status entitle her, in her own opinion, to order others around and judge them as she pleases. When she learns of the rumored engagement between her nephew, Mr. Darcy, and Elizabeth Bennet, she immediately sets out to confront Elizabeth about the unsuitability of the match based on Elizabeth's lower social status. While the rumor isn't true, it also isn't too far from the truth. Lady Catherine doesn't care if Elizabeth would make her nephew happy; she doesn't care if he loves her. Her main concern is what a degradation it would be for Darcy to marry Elizabeth, a prejudice she has based on her knowledge of Elizabeth's family and connections. Lady Catherine had heard about the behavior of Elizabeth's sister, Lydia, as well as her mother's lack of family status, and thus she believes that she can accurately judge Elizabeth based on that knowledge, without really knowing Elizabeth or what her relationship with Darcy is like. Lady Catherine's prejudice against Elizabeth eventually alienates her from her nephew and his household after he and Elizabeth are married.