There are several moments interspersed throughout "The Mark on the Wall" in which the narrator reflects on the nature of human thought. Comparing thoughts to ants, Woolf emphasizes the fickle nature of human mental processes:
How readily our thoughts swarm upon a new object; lifting it a little way, as ants carry a blade of straw so feverishly, and then leave it . . .
Using the voice of the narrator, Woolf performs a kind of meta-reflection on her own stream-of-consciousness writing style. Humans, Woolf's narrator claims, lack fixity of purpose and endurance within our stream of thought; indeed, the narrator herself does not come to any fixed conclusion by the end of the story. Woolf's writing style, true to its name, attempts to reflect the actual progression of human thought and life: not structured, in three or four succinct acts, but a series of loosely connected threads that do not always result in a settled conclusion. Just as ants "swarm upon a new object" only to later abandon it, so does the narrator dwell upon a certain topic briefly, only to quickly move on to the next one. This is the nature not only of the narrator's thoughts, but also of Woolf's writing style, which she extrapolates outward to reflect the unstructured trajectory of human life.
Early in "The Mark on the Wall," the narrator imagines the previous owner of her house as a partner in conversation, explaining to her his reasons for leaving. Promptly, however, this imagined conversation is metaphorically "torn" from her thoughts:
[He] was in the process of saying that in his opinion art should have ideas behind it when we were torn asunder, as one is torn from the old lady about to pour out tea and the young man about to hit the tennis ball in the back garden of the suburban villa as one rushes past in the train.
In the above metaphor, Woolf equates the ever-moving stream of the narrator's conscious thought to the movement of a train. The imagined conversation flashes through the narrator's mind and is then abandoned, as fleeting as the momentary voyeurism train passengers enjoy into the lives of passersby. The narrator's mind subsequently wanders elsewhere; and Woolf describes the momentary speculation and subsequent abandonment of a thought as being "torn asunder." This choice of words is distinctive, conjuring up violent, abrupt movements not typically associated with serene contemplation. Woolf's use of such violent movement in her metaphor suggests that something unpleasant has prompted the narrator's introspection—perhaps the war, which is not discussed in detail but is nevertheless alluded to, and clearly weighs heavily on the narrator's mind.
