It takes seven minutes for the coils to finish cooling and warm back up again. You have watched the lamp reignite approximately a dozen times tonight. The buildup leading to its combustion is always a minor drama. As the coils warm, the wisp of ember expands, so gradually that you barely notice. Its orange core keeps on thickening in diameter, pushing out through the plastic casing, until every inch of it is filled. Before the lamp snaps back on, the casing simply smolders there awhile, a redhot block in the blackness. It looks like a brick being baked in midnight’s kiln. It throbs orange. Then, just as unexpectedly as it snapped off, the bulb reignites. A starburst explodes outward from the lamp, sharp spokes of light that asterisk the air.

Every time the lamp combusts like this, the push mower’s silhouette is thrown into relief, a jag of shadow beside the shed entrance. All night it has not moved. Now, if you were the owner, and if you believed that that silhouette actually was an incubus, and if hour after hour you watched the lamp flash on to reveal that it had not budged, you would find this tremendously unsettling. Not only that the silhouette has not changed positions but also that, during the fifteen-minute intervals when it is lit, the silhouette does not even flinch. It does not so much as turn its head or shift its weight to a different leg. With a statue’s poise, or a push mower’s, it remains fixed there, inhuman and unmoving.

That is what would unsettle you about the silhouette, if you were the owner: the lengths to which it is willing to go to convince you that it is a push mower. How it stands precisely in the push mower’s place. How it keeps its arms folded at its sides and its legs pressed together, the better to simulate the push mower’s shape. How it will go on standing there as still, and for as long, as it takes to be mistaken for an inanimate object, and how only then—when you have finally mistaken it for a push mower and reassured yourself, After all, it is only the push mower—only when you have turned your back on the so-called push mower and abandoned your vigil before the bedroom window, how only then will the silhouette, taking advantage of your negligence, reveal itself for what it truly is: from the straight black line it makes, its arms will unfold liquidly at its sides, and the lower half of the silhouette’s body scissor apart into two dark legs. This, this, is what unsettles you: how in one second, after hours of ruthless patience, the silhouette will finally transform itself, shifting from a push mower into a man.

There is something unsettling about the sight of it, when the lamp is lit. A dark shape in an orange haze. It really does look human. It really does look as if it is looking back at you, right through the bedroom window. And even more unsettling than this, you find, are those periodic seven-minute intervals—such as now—when the lamp is not lit. For then the silhouette merges completely with the darkness, and you cannot see it. During this time, for all you know, it could be anywhere: not in its usual position beside the entryway, but halfway across the yard, lurching toward the cabin. While you have kept your eyes trained on the toolshed’s outline—as you do now—waiting impatiently for the safety lamp to reignite, the incubus could already be cutting across the weeds. Then, when the lamp finally does flash on, you might see only the awful emptiness of that cone of light, untenanted at last. For if suddenly, for the first time in hours, the cone of light were empty? Then you would know for certain. You would know—beyond a shadow of a doubt—that it is not and never has been a push mower, that it has always been a nightmare, merely biding its time. And at the sight of the vacant cone your mind would jam with panic, trying to calculate where, by now, this incubus could be.