I don't know what I believe, but I know what I've seen and heard. My husband, my dog and I have all heard the sound of our cat, who died two years ago after almost 20 years with us, jumping off his favourite bookcase. It is a very distinctive and unmistakeable two-beat "ka-thud" followed by the tap-tap-tap of paws. I have only heard it once - my husband was there and heard exactly the same thing at the same time, and the dog also reacted. My husband has heard it on other occasions. Kitty has also pushed open our bedroom door, twice. Again my husband and I both experienced it - it wasn't just that the door opened - it was pushed with the same pressure, the same sound, the same "feeling" as the cat used. Can't explain it; don't care if others don't believe it; but I know that it happened.