This might be an easy metaphor for Robert, or it might be something else. It might be watching the contours of the lane you're in while marking progress of headlights coming toward you: their position steady or wavering or a sudden jutting light up the rise of a blind rise or curve.
Or this might be about the dark itself and the way dark absorbs and dissolves apparent structures to the right or to the left. Standing structures, steady structures that catch the corner of the eye and tug just enough to say, home or barn or post.
Or could be the moon exposed suddenly to the left, light spreading rapidly across a field of nodding high grass, only to snap off suddenly against the edge of a barn or tree-lined side road.
This might all just be marking time in the dark as the eye interprets things it thinks it knows, while the mind traces an intermediary point between pigments illuminated by twin artificial lamps.