" After I give lectures—on almost any subject—I often am asked, “Do you believe in UFOs?” I’m always struck by how the question is phrased, the suggestion that this is a matter of belief and not of evidence. I’m almost never asked, “How good is the evidence that UFOs are alien spaceships?” I "

― Carl Sagan , The Demon-Haunted World: Science as a Candle in the Dark