The narrator speaks in the first person, leaving room for indecision and unreliability, as in the passage below:
But as for the mark, I'm not sure about it; I don't believe it was made by a nail after all; it's too big, too round, for that.
Because readers receive the narrator's thoughts in an unfiltered stream, the tone of this work varies greatly, reflecting the narrator's frame of mind at any given moment. In passages like the one above, the narrator quickly moves from certainty to uncertainty, the first-person narration making the reader unsure which assertions to trust. Such thoughts are presented by Woolf, through the narrator, not as facts but as opinions —half-formed ideas and arguments, in the process of being fully articulated. Though the narrator is not obviously unreliable, neither does Woolf present her as implicitly trustworthy: her thoughts and feelings are as subjective as those of any human being, including the reader. In this situation, any interpretation of the "facts" - Woolf's, the narrator's, or the reader's - is valid, because there is no singular objective, omniscient narrator. This is true not only of "The Mark on the Wall," but of life: objective truth is simply the point of view that a majority of people agree upon. Through the narrative's tone, then, Woolf challenges the presumption of "true objectivity."