Fenestration
They ought to have considered more thoroughly where to place the windows on the wall.
I don't usually sleep well. I roll around on the mattress, stare at the ceiling, and make decisions to get off the bed and go fetch something to drink or eat at the middle of the night even when I'm not really hungry.
Everytime I got to the kitchen, though, I kept feeling that there was something else moving. I could catch glimpses of it in the corner of my eye, shifting. It's always on the floor, and always in front of me - maybe a few paces distance off, always on that same spot. But everytime I froze and turned my head towards the source of the movement, there was nothing to be seen but the faint outlines of the tiles on the kitchen floor, in the dark.
This troubled me for quite a while, until a few days ago I managed to resolve this perplexion. So it turns out that the human peripheral vision is much more sensitive to motion and changes in brightness, in comparison with the superior sensitivity to colour and shape of central regions of the visual field. And that day, by chance, I glanced upwards, and was reminded thatthere was a window high up on the opposite wall - probably for ventilation purposes. There was little light outside, but there was, at least, the moon or stars or whatever proportion of the light from street lamps that managed to make it through an opening of that elevation; and so there formed a barely noticeable patch of light on the floor, at that exact spot, a few paces off, in front of me. That variation of brightness on the tiled floor, I see now, is but the movement of the subtle shadow cast by my own fidgeting self.
I pay no thought to that movement, now that I understand it.
