Tongue-in-cheek
Austen’s sentences are short and sweet – but they sure do pack a wallop. She’s a master of ambiguous sentences which could be a character’s thoughts but could also be the narrator’s voice. The official term for this is "free indirect discourse," and Austen was one of the first authors to use it well. Check out moments when the narrator (or is it Emma?) is thinking about other characters in the novel. It’s hard to tell whether Emma is the one thinking these thoughts or the narrator – which is Austen’s point. Making the most of this ambiguity helps Austen to craft a pretty well-developed sense of irony about the social world she invents. She’s often in Emma’s head, but using free indirect discourse allows her to be ironic about Emma’s own thoughts, as well.
Not everything is under control, though. Whenever Emma (or another character) gets worked up, Austen’s sentence structure changes. She uses lots of dashes to help generate a sense of confusion – like her characters can’t quite figure out how to form a sentence – because they’re so – so – so – confused. Check out the start of Mr. Knightley’s proposal for a great example of this:
"As a friend!"—repeated Mr. Knightley.—"Emma, that I fear is a word—No, I have no wish—Stay, yes, why should I hesitate?— I have gone too far already for concealment.—Emma, I accept your offer— Extraordinary as it may seem, I accept it, and refer myself to you as a friend.—Tell me, then, have I no chance of ever succeeding?"
Notice all the dashes and unfinished sentences? They indicate the hurried (and anxious) rush of feeling that Mr. Knightley is about to release. Can’t you almost see him struggling with himself over how (or if) he should tell Emma of his love? Austen may not allow her narrator to enter into Mr. Knightley’s head as often as she does Emma’s, but moments of broken dialogue like this one help to indirectly show us what characters are thinking.
Of course, Austen’s also a master of dashes in other situations, as well. Take, for example, any extended speech by Miss Bates. We’ve included one of our favorite ones (from the party at the Crown):
Ah! here's Miss Woodhouse.—Dear Miss Woodhouse, how do you do?— Very well I thank you, quite well. This is meeting quite in fairy-land!— Such a transformation!—Must not compliment, I know (eyeing Emma most complacently)—that would be rude—but upon my word, Miss Woodhouse, you do look—how do you like Jane's hair?—You are a judge.— She did it all herself. Quite wonderful how she does her hair!— No hairdresser from London I think could.—Ah! Dr. Hughes I declare—and Mrs. Hughes. Must go and speak to Dr. and Mrs. Hughes for a moment.—
Whew! We’re getting dizzy just trying to follow it! Of course, it’s pretty easy to imagine that Emma has some things to say in between Miss Bates’ mile-a-minute speeches, but our narrator doesn’t allow us to see them – perhaps as a way of emphasizing the silliness and, well, irrelevance of everything Miss Bates says. In other words, we don’t hear Emma’s speech because Miss Bates probably doesn’t hear it herself. She’s already thinking ahead to the next interaction she can have with other people. It’s almost like a form of stream-of-consciousness – except that Austen uses it to prove that Miss Bates doesn’t have much consciousness to speak of.