More on the topic of letters. I love Byatt's thoughts on literature and its forms.
"Letters, Roland discovered, are a form of narrative that envisages no outcome, no closure. His time was a time of the dominance of narrative theories. Letters tell no story, because they do not know, from line to line, where they are going. [...]
Letters, finally, exclude not only the reader as co-writer, or predictor, or guesser, but they exclude the reader as reader, they are written, if they are true letters, for a reader."