The postulated author

Our conversation reminded me today of the previous discussion we had about whether a writer is always a great writer or simply when they produced the work. If I understood the distinction we made today between author and writer, was that the writer is all the features of the person including their biographical information. The author is the intentional agent who at the time of writing the work, has the motive of communicating something specific through the literary work. In that sense it seems like the postulated author is a state of mind in which the writer enters when producing the text. The difficulty then in trying to use the retrieval process would be that we would have to guess what the writer was intending in that one specific state, facts about the previous and remaining events and experiences of their lives would only serve to supplement our understanding of the writer and not the author. These are some points I believed were raised in our converstaion today but if there is anything I am unclear of comments, opinions, and clarifications are always welcome.