Do you believe in ghosts?

Late at night this weekend Ponder was sleeping in the hammock. As I have been working long lately and am knackered when I come home, I don't have much hammock time for him. He hates being robbed of his special time at the computer, therefore he enjoyed it thoroughly on the weekend. So much in fact that my feet fell asleep trying to accommodate him the right way.
Suddenly he jumped up, though, ran to the staircase and started staring upwards while making these funny high-pitched sounds that I had never heard from him before. From his sister, yes, but not from Pon.

I called him, but he didn't move. So I went over there to look for the exciting spider, fly or bug that fascinated him so much. Nothing. I heard nothing, I saw nothing. He kept looking up there for five minutes, singing. And I took the chance to take a picture. Suddenly he looked at me, walked over the tall guy's desk and demanded to be snuggled again.


I still wonder what he heard or saw. Ghosts? Spirits? Some kind of rare, invisible bug? Something in the attic that my ridiculously weak human ears couldn't hear? A mouse, a weasel or a bat? Is there a ghost living in our attic? Did he wait for the feline portal to open up to attend a cool party? Or did he just think it was time to scare me a little?
I don't know and I probably never will. Darn. I want to be a cat in my next life.