Lady Catherine specifically mentions the impropriety of Elizabeth's mother, the lack of family rank on that side, and the elopement of Lydia as reasons that forbid the connection between Elizabeth and Darcy. Elizabeth is sarcastic and elusive during this interview. She does not want to give Lady Catherine any information regarding her history with Darcy, and so sidesteps the questions. When directly asked if Darcy has proposed, Elizabeth shoots back, "Your ladyship has declared it to be impossible." Only when asked if they are engaged does Elizabeth relent and confirm that they are not, but she will not make any promises to Lady Catherine, and actually ends the interview herself.
Lady Catherine de Bourgh comes to Longbourn to try to break up what she suspects is a relationship between Elizabeth and Darcy. She is extremely rude, and insists that Miss de Bourgh has been promised to Darcy since infancy. She belittles the Bennets’ worth, and chastises Elizabeth for her sharp tongue. Elizabeth tells her to mind her own business. She, as has been shown throughout the novel, is not afraid of Lady Catherine.