Quote 1
"Not so hasty, if you please. I have by no means done. To all the objections I have already urged, I have still another to add. I am no stranger to the particulars of your youngest sister's infamous elopement. I know it all; that the young man's marrying her was a patched-up business, at the expence of your father and uncles. And is such a girl to be my nephew's sister? Is her husband, is the son of his late father's steward, to be his brother? Heaven and earth! —of what are you thinking? Are the shades of Pemberley to be thus polluted?" (56.63)
To be fair, we sympathize with not wanting to be related to Wickham—but not because he's basically a servant's son; because he's a deceitful, gambling seducer. Either way, Lady Catherine's response is hilariously over the top: "Are the shades of Pemberley to be thus polluted," as though Elizabeth is actually going to make the estate dirty.
Quote 2
"Miss Bennet I am shocked and astonished. I expected to find a more reasonable young woman. But do not deceive yourself into a belief that I will ever recede. I shall not go away till you have given me the assurance I require." (56.56)
And by "reasonable young woman," Lady Catherine means "someone who, like everyone else, will do exactly what I say." Lady Catherine is ridiculous, of course, but these moments really show us how awesome Elizabeth is.
Quote 3
"Not so hasty, if you please. I have by no means done. To all the objections I have already urged, I have still another to add. I am no stranger to the particulars of your youngest sister's infamous elopement. I know it all; that the young man's marrying her was a patched-up business, at the expence of your father and uncles. And is such a girl to be my nephew's sister? Is her husband, is the son of his late father's steward, to be his brother? Heaven and earth! —of what are you thinking? Are the shades of Pemberley to be thus polluted?" (56.63)
We forgive you for getting a little confused with all these uncles and nephews. We're not saying family doesn't matter, but Lady Catherine really seems to be taking it a step too far. It's like she thinks she's going to be polluted by being very, very, very distantly related to Wickham.