a ghost? a cat?

I went to the Office on Saturday, because I had some work I hadn’t done during previous week. The University building was completely empty. I went to my room and I opened one side of a window. When I was looking through documents I felt that someone is staring at me. It was a cat. He was sitting behind a window (this closed part). He looked as a sculpture. He was gray, classical alley cat. I decided not to move, because I didn’t want to scare him and I went back to my work. After about 10 minutes I looked at the window again. The cat sat in the same position but he moved to a part of the window which was opened. He was observing me rally carefully. It provoke a question "WHY wasn’t the cat afraid of me?". The answer might be, for example that, in a body of the cat there was incarnated a soul of some student from middle ages, who illegally was playing dice whilst studying at University… And his goal was to threaten a university employee… I decided not to take this line of thought. I’m not afraid of cats or ghosts. My irrational fears are much more sophisticated (and funny: fortunately for my friends and unfortunately for me). I’m afraid of aliens sitting in bushes at night… After half an hour the cat disappeared, leaving me with my bureaucracy. The cat was really beautiful. He didn’t look as a homeless cat. I think that it was a kind of rascal looking for adventures in his safe live in some good family.