Quote 13
"Pray, my dear aunt, what is the difference in matrimonial affairs, between the mercenary and the prudent motive? Where does discretion end, and avarice begin? Last Christmas you were afraid of his marrying me, because it would be imprudent; and now, because he is trying to get a girl with only ten thousand pounds, you want to find out that he is mercenary." (27.8-9)
Lizzy points out to her aunt that tying marriage to money like this just makes the entire population hypocritical: Wickham can't marry her because that would be "imprudent," i.e. really dumb. But when he goes after an heiress, he gets called "mercenary," i.e. a gold-digger. This is literally a lose-lose situation for Wickham, not that he needs any help being a loser.
Quote 14
"If you, my dear father, will not take the trouble of checking her exuberant spirits, and of teaching her that her present pursuits are not to be the business of her life, she will soon be beyond the reach of amendment. Her character will be fixed, and she will, at sixteen, be the most determined flirt that ever made herself or her family ridiculous; […] Oh! my dear father, can you suppose it possible that they will not be censured and despised wherever they are known, and that their sisters will not be often involved in the disgrace?" (43.18)
Mr. Bennet thinks that Lydia's behavior isn't going to reflect badly on Lizzy or Jane, but he's wrong. Maybe if he ever left his library to supervise his daughters at one of those balls where they make themselves ridiculous, he'd actually know something about how the world works.
Quote 15
"To yield readily—easily—to the persuasion of a friend is no merit with you."
"To yield without conviction is no compliment to the understanding of either."
"You appear to me, Mr. Darcy, to allow nothing for the influence of friendship and affection. A regard for the requester would often make one readily yield to a request, without waiting for arguments to reason one into it." (10.35-37)
In this banter between Darcy and Elizabeth (which, incidentally, is one of the first times he gets a sense of the "lively mind" that he talks about falling in love with later), we get one of the several philosophical questions discussed in the novel: just how much should you listen to your friends? Should you listen or should you demand proof for their opinions?