A Nod to Harry...

Harry Houdini didn't believe in the supernatural, although he deeply wanted to. He desparately wanted to contact his deceased mother, but was never able to do so; in the process he debunked many mentalists. When he died, he gave his wife a code word that he would use if he was able to come back across, which he never did.

Of course, this only means that he couldn't make the journey, not that other spirits were incapable of it. To read all about Harry, though, follow this interesting link:

http://www.prairieghosts.com/houdini.html