Meaning is structural
The quest of the Humanities is to attempt to arrive at some kind of valid, plausible explanation of reality. The human supposes that life is supposed to be meaningful, but the meaning is not obvious in life, nor in literature for that reason. Instead, there are systems that imply order and meaning, but without revealing their true origin or nature to the reader. Therefore the reader is imbedded in structural maps of meaning where symbols and plot devices are suggestions to reader that meaning could be imposed on the text or perhaps, if one is optimistic, maybe they could even be deduced.
The progress of stories
A lot of the codification of a story, says Barthes in this book, lies in the progress of a plot in a story, because that is a structural component of a book which guides the reader through the novel's various experiences. Barthes says that this is a part of the novel's ability to carry meaning, because the reader experiences the plot in a meaningful way, understanding the narrative to be a kind of metacognitive domain where they are subjected to a new point of view.
Enigma and mystery
Because the symbols of a story involve codified information that is often left to the reader to deduce or predict, Barthes's theorizes that there is a mechanism by which the story suggests to its readers where something might be veiled in mystery. Of course this is true in general, because the reader has to move through a book page by page, leaving the author to decide what order to put information in. This necessarily creates a kind of tension where the reader is being suggested in certain respects, but in other respects, they are left to their imagination.
