Miss Pierce, how can you be such a foolish ignorant girl? Asked to think you could afford to pay Mr. Higgins. The author uses the line. I love to show the reader that.

Miss Pierce is naive and perhaps overreaches her financial capabilities. She seems to be overly optimistic or unaware of the true cost of engaging with someone like Mr. Higgins. It might also suggest a sense of desperation or determination on Miss Pierce's part, depending on the context. The author uses this criticism to underline her character flaws and present her as someone who is yet to understand the realities of her situation.

Based on the line you provided, it seems like the author is using this statement to reveal Miss Pierce's irrational thinking and perhaps her overestimation of her own financial means. The author may want to highlight Miss Pierce's lack of understanding or naivety regarding her ability to pay Mr. Higgins. The phrase "foolish ignorant girl" suggests that the author wants to portray Miss Pierce as someone who is unaware of the reality of her situation. This line could serve to create a contrast between Miss Pierce's perception of herself and the true feasibility of her being able to afford Mr. Higgins.