black and white different

A few nights ago, I wanted to tidy my son’s room. I was shocked when I saw the ceiling fan is black. In my memory it was white. I was in disbelief, and millions of questions popped into my mind. How come, somebody changed the fan? Or painted it black? Or my memory is wrong, no way, I cleaned it a few times before. Or am I insane? I stood on the bed and examined the fan carefully, it is an old fan, and no sign of it being repainted. My memory was wrong, and so wrong! I texted my son the next morning, “Do you remember the color of the ceiling fan in your room?” “Don’t remember, light gray?” he replied. Ha-ha, I’m not insane, and just a little bit worse than him. But I was in another shock, the thing I membered, and the thing really was could be black and white different!