A few days ago, late in the evening, I walked into my living room which has a high a peaked ceiling.  Just as I stepped into the room, I glanced up at the peak windows and the night reflected a swirl of black above me.  My mind immediately dismissed it as shadows from a ceiling fan.  Then my conscious thoughts caught up and realized that this house, which I have lived in only two years, does not have ceiling fans.  I looked up again and the black swirl was no longer there.  So I began to convince myself it had been an odd shadow or my eyes reacting to the change in light.  Well enough.

Until I turned and saw it again in a different corner of the room.  It was a set of spiral bands of black pivoting around a central point.  But the arms were not straight, they were twisted as if distorted by the rotational movement.  Once again, I tried to dismiss it in my thoughts, but I had no explanation.  Then I realized what made the sight so odd at first.  The first time I saw it, I saw it as a reflection in the glass, which would place it above my head.  The reflection was not complete, as the source overlapped the edge of the glass, so I only saw about two thirds of the swirl.  The second time I saw it in a specific location in the opposite corner of the room, away from me and I could see all of it.  If it was an illusion or my eyes playing tricks, why would there be a reflection of a partial image in the glass, rather than the whole imaginary image?