I have been reading the book "Pride and Prejudice" and found the following extract from a dialogue between Mr. Darcy (?) and Miss Elizabeth Bennet (?), in chapter 10, very difficult to understand.

"...Miss Bennet, that the friend who is supposed to desire his return to the house, and the delay of his plan, has merely desired it, asked it without offering one argument in favour of its propriety"
"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"

Could somebody please explain to me that what they are saying and in particular, how to understand the meaning of the phrases highlighted ?

Thanks very much,