Novels have layers. Theme is what the story is about on a deeper level than the plot details. It’s the big meaning, and often it’s a moral meaning. Love, honor, family, and revenge are all some common, underlying themes.
I think of the scenes in my books as if they were scenes in a movie. Each conversation is a scene.
Sometimes, we find ourselves in Outer Mongolia as we wrangle our words. Our mind is off chasing squirrels, and our fingers are madly keying dialogue. It happens, and then we find ourselves writing paragraphs of discussion regarding the vase on the kitchen table. Why are we discussing this vase? If there is a reason that will emerge later, keep it. If it is just idle fluff, lose it.
I actually have a scene in one of my forthcoming books where the characters do just that. They are discussing a vase that was made by a child, but the conversation is not important for the sake of the vase, nor is it really about that object. It is there to expose how important an absent person is to one of the speakers, and the brief interaction between the two speakers endears to the reader one of the characters who will later meet a sad end. The underlying themes of this book are brotherhood, family, romantic love, honor, duty. The obvious theme is the successful resolution of a quest. The core plot device around which the story evolves is an ongoing War of the Gods, and the world in which the tale is set in is their battleground, offering all sorts of opportunities for mayhem.
Consider the first scene of one of my favorite movies of all time, The Matrix. This movie has a lot of action, but it has a lot of dialogue also, and that dialogue advances the plot and never loses the theme of the story.
The conversation concerns a drug deal, but the underlying theme is never lost. The key words are in the first line, written on the computer, The Matrix has you, the third line, follow the white rabbit, and in that very last line, telling Neo to unplug. The Matrix is all about waking up, about what reality is, and about Neo as the potential savior of the world, which has been enslaved by a virtual reality program. It is about escaping that program. The conversations that happen in the course of the film all advance that theme, even the minor interactions, from the first conversation to the last.
We must approach conversations in our novels as if they were scenes in a movie. In a good movie, we don’t notice it, but there is an arc. In a story arc, a character undergoes substantial growth or change. It ends with the denouement in the last third or quarter of a story. The end of a narrative arc is the denouement, the final resolution. It shows what happens as a result of all the conflict that the characters have gone through.
If we don’t keep the arc of the story moving with each scene, we will lose our reader, and to that end, each conversation must reflect the underlying themes of the story without beating the reader over the head with it. As in real life, some of the people know more than others, and to advance the plot and the theme, small clues must come out over the course of each scene, each scene building to the finale.
I‘ve said this before, but we must build the overall arc of the story from scenes, each of which is a small arc, in the same way a gothic cathedral is constructed of many arches that all build toward the top. The underlying arches strengthen the overall construction. Without arches, the cathedral wouldn’t remain standing for very long. The novel is a cathedral and your scenes are the arches that hold it up. The conversations that form those scenes are miniature arches, each with a beginning, a high point, and a resolution.