When Emma sees his letter to Harriet, this is her reaction:

She read, and was surprized. The style of the letter was much above her expectation. There were not merely no grammatical errors, but as a composition it would not have disgraced a gentleman; the language, though plain, was strong and unaffected, and the sentiments it conveyed very much to the credit of the writer. It was short, but expressed good sense, warm attachment, liberality, propriety, even delicacy of feeling.