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.
And two pages at the end which describe the process of reading (specifically re-reading) better than anything else I've encountered, from which I excerpt a part:
Now and then there are readings that make the hairs on the neck, the non-existent pelt, stand on end and tremble, when every word burns and shines hard and clear and infinite and exact, like stones of fire, like points of stars in the dark--readings when the knowledge that we shall know the writing differently or better or satisfactorily, runs ahead of any capacity to say what we know, or how. In these readings, a sense that the text has appear to be wholly new, never before seen, is followed, almost immediately, by the sense that it was always there, that we the readers, knew it was always there, and have always known it was as it was, though we have now for the first time recognized, become fully cognisant of, our knowledge.