How does Mr.Darcy come to admit that he was once a victim of first impressions and premature judgment?

Volume III, Chapter 3 Summary:

During their visit to Pemberley Miss Darcy receives them with civility, although she is very shy. Mrs. Hurst and Miss Bingley say very little, and the conversation is carried on mostly by Mrs. Annesley (an acquaintance), Mrs. Gardiner and Elizabeth. Elizabeth both hopes and fears that Mr. Darcy will join them.

After a while Mr. Darcy does join them, and his actions are closely scrutinized by Miss Bingley and Miss Hurst. When Miss Bingley notices that Mr. Darcy is trying to get Elizabeth and Georgiana to converse, she asks Elizabeth a question about the militia. Elizabeth answers with composure, and notices that both Mr. Darcy and Georgiana are pained by the allusion to Wickham.

After Elizabeth and Mrs. Gardiner take their leave, Miss Bingley speaks negatively about Elizabeth to Georgiana, but Georgiana's opinion is fixed firmly in Elizabeth's favor by her brother's commendations. Miss Bingley also repeats her criticisms of Elizabeth to Darcy, and after much provocation he coolly answers that he considers Elizabeth one of the most handsome women he has ever met, and then walks away.

Volume III, Chapter 3 Analysis:

Austen again brings the theme of class barriers to the fore in this chapter, demonstrating how the status accorded on the basis of class may have little or no connection to a person's virtue or merit. Mrs. Hurst and Miss Bingley are extremely class-conscious and look down upon Elizabeth and the Gardiners for their lower social status. Yet the very pettiness and lack of civility which Mrs. Hurst and Miss Bingley show are proof that they lack any genuine good breeding or nobility of character. Throughout the novel, Elizabeth has shown little concern for the merely superficial aspects of class barriers, and bases her judgments on what she believes to be the quality of a person's character.

While Mr. Darcy used to have an attitude about class similar to that of Mrs. Hurst and Miss Bingley, it seems that his relationship with Elizabeth has effected a substantial change in him. While he still respects status distinctions and rules of propriety, he is now able to look beyond class prejudices and to judge people according to their moral worth rather than their social class.