“Very thoughtful of Colonel Campbell, was not it? – He knew Miss Fairfax could have no music here. I honour that part of the attention particularly; it shews it to have been so thoroughly from the heart. Nothing hastily done; nothing incomplete. True affection only could have prompted it.” Emma wished he would be less pointed, yet could not help being amused; and when on glancing her eye towards Jane Fairfax she caught the remains of a smile, when she saw that with all the deep blush of consciousness, there had been a smile of secret delight.
– Jane Austen
Emma, Chapter 28. You would need to be a linguistics expert to interpret the secret languages spoken and unspoken during the piano scene at the Bates’s apartment. Frank Churchill is talking about the music that came with the piano Jane Fairfax is playing. To Jane, secretly engaged to Frank, he is expressing his “true affection” for her. For it was he who secretly bought her the piano and music. But to everybody else’s ears, Frank is saying that Colonel Campbell supplied the music and is implying the piano was a gift from him too. Emma of course misreads everything she hears and sees. She believes that the piano came from Mr. Dixon, the husband of Jane’s friend. To Emma, the reference to “true affection” is a dig at Jane’s supposed affair with Mr. Dixon. Jane’s blushes and smile are enough to confirm Emma’s suspicions.