An Optical Illusion

"Stella! Stella!" I called from the bed, but our little dog wouldn't come. I kept looking down at the floor, and I could see her ears beyond my pillow. She had to have heard me. I continued to say her name, but she was not going to move, which I found strange because she always comes when she is called.

Then I sat up in bed and discovered that what I was seeing was not Stella at all. It was my boot. My eyes had clearly deceived me.