...I am, in short, a rationalist and believe only that which reason tells me is so. Mind you, this isn’t easy. We are so surrounded by tales of the supernatural, by the thunders of the powers to be who attempt with all their might to convince us of the existence of the supernatural, that the strongest among us may feel himself swaying.Something like that happened to me recently. In January 1990, I was lying in a hospital bed one afternoon and my dear wife, Janet, was not with me, but had gone home for a few hours to take care of some necessary chores. I was sleeping, and a finger jabbed at me. I woke, of course, and looked blearily to see who had awakened me and for what purpose.My room, however, had a lock, and the lock was firmly closed and there was a chain across the door too. Sunlight filled the room and it was clearly empty. So were the closet and the bathroom. Rationalist though I am, there was no way in which I could refrain from thinking that some supernatural influence had interfered to tell me that something had happened to Janet (naturally, my ultimate fear). I hesitated for a moment, trying to fight it off, and for anyone but Janet I would have. So I phoned her at home. She answered immediately and said she was perfectly well.Relieved, I hung up the phone and settled down to consider the problem of who or what had poked me. Was it simply a dream, a sensory hallucination? Perhaps, but it had seemed absolutely real. I considered.When I sleep alone, I often wrap myself up in my own arms. I also know that when I am sleeping lightly, my muscles twitch. I assumed my sleeping position and imagined my muscles twitching. It was clear that my own finger had poked into my shoulder and that was it.Now suppose that at the precise moment I had poked myself, Janet, through some utterly meaningless coincidence, had tripped and skinned her knee. And suppose I had called and she had groaned and said, I just hurt myself.Would I have been able to resist the thought of supernatural interference? I hope so. However, I can't be sure. It's the world we live in. It would corrupt the strongest, and I don't imagine I'm in the strongest.

~ Isaac Asimov