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Quote :Narrative Discourse: An Essay in Method
This perhaps authorizes us to organize, or at any rate to formulate, the problems of analyzing narrative discourse according to categories borrowed from the grammar of verbs, categories that I will reduce here to three basic classes of determinations: those dealing with temporal relations between narrative and story, which I will arrange under the heading of tense; those dealing with modalities (forms and degrees) of narrative 'representation,' and thus with the mood of the narrative; and finally, those dealing with the way in which the narrating itself is implicated in the narrative, narrating in the sense in which I have defined it, that is, the narrative situation or its instance, and along with that its two protagonists: the narrator and his audience, real or implied. […] this term is voice.
Narrative theory is often focused on structure and on defining the various parts that make up a structure. In this passage, Genette outlines his own take on the subject by drawing on terms that we often use when discussing grammar: tense, mood, and voice.
The first category, "tense," has to do with the relationship between narrative and story. If story is the raw material and narrative the finished product, with the writer ordering the events of the story in whatever way he or she sees fit, then "tense" refers to the importance of time in this arrangement: it's all about asking how and why events are ordered in a certain way. It's also about asking how often events are portrayed in the narrative (their frequency) and how long they go on (their duration). In all cases, the point is to look not just at time in the factual sense but also at how it's treated (or twisted) in the narrative.
The second category is "mood," which refers to the position that the narrator takes within the text. Here, we need to think about the narrator's standpoint and how close or distant they are from the events going on in the world within the narrative. Remember the term "focalization"? The perspective of the narrator in relation to the stuff that's being depicted? Well, this is what Genette is talking about here when he refers to mood.
The third category that Genette mentions in this passage is "voice." It's similar to mood, but it shifts emphasis to the question of who narrates and from what position. Is the narration coming from inside or outside the text? And is the narrator a character within the story? According to Genette, these are the sorts of things that we need to ask when dealing with narrative voice.