An anonymous woman provides a first-person account of a day in the middle of January when she noticed a mark on the wall. In trying to recall the exact date of this remembrance, she calls to mind other images from that moment: a fire burning, the light cast across the pages of a book, flowers in a bowl, and the fact that she was smoking when she apprehended the mark. It was a small black contrasting against the white wall, situated about half a foot above the fireplace mantel. These particulars stimulate a series of explanations quickly considered and then cast away as to why the mark might be there. She rejects the idea of the mark being the result of a nail because the only reason to place a nail there would be to hang a picture frame. The idea of the picture frame sends her off on a tangent about the personalities of the previous occupants of the house.
A moment’s temptation to get out of her chair for a closer inspection turns into a philosophical rumination on how many possessions are lost over the course of a lifetime, which leads, naturally, to a recounting of several of the things she once owned that are now gone. After comparing the act of living to a being a package zipping through a vacuum chute following a growing frenzy about how haphazard the whole thing really is, she suddenly grows melancholic with morose thoughts of death before pondering over the idea that the mark on the wall is not a hole, after all, but is perhaps just a circular bit of inky substance.
The interruption of her thoughts by the sound of a tree tapping at her window causes her thoughts to change tracks; suddenly, she is thinking of Shakespeare sitting in a room with a fire burning while great creative thoughts rain down from the heavens into his mind. Quickly tiring of heavy historical thoughts about the Bard, her train of thought jumps again to predict that one day writers will realize the value to be found in composing characters based upon the phantoms that are the ever-changing faces of a person cast in reflections. These writers will leave behind dead-end attempts to impose false realities of the external world and seek to pursue the greater truths that remain unseen. The idea of those deadened realities brings to mind thoughts of table-setting etiquette for Sunday luncheons as the feminine analogue to the masculine rules of etiquette for addressing dignitaries.
Now she views the mark as not entirely circular and possibly projecting outward from the wall. Perhaps it is a shadow. These considerations lead to wondering about the tumuli in South Downs and whether they are camps or tombs; only an antiquary would know, so she wonders what kind of personality leads to a career as an antiquary, which ultimately winds up with considerations of proof only being known when touched, and if a thing cannot be proven, then it cannot be known.
So once again, there is conflict over getting up for a closer inspection—but, after all, knowledge is attained by thinking, and one can think sitting down as well as standing up. The jumble of thoughts that have entered and exited through her mind commingle at the point at which she decides she must solve the mystery of the mark by getting up.
She then decides that to get up would be playing victim to the very trap that Nature is trying to set. The act of thinking about the mark brings excitement and pain, and Nature is attempting to end that by inducing her to action. So, she focuses her thoughts on the sensual qualities of wood.
These pleasant distractions are interrupted by the announcement of a second person—almost certainly the narrator’s husband—in the room, who intends to go out and buy a newspaper even though there’s never anything in the paper these days anymore but bad news about the war. The anger intensifies into a more personal sense of dissatisfaction and outrage with as he exits with the words, “All the same, I don’t see why we should have a snail on our wall.”
She realizes that, indeed, the mark on the wall is a snail.
