" Old-fashioned people still say “bless you” when one sneezes, but they have forgotten the reason for the custom. The reason was that people were thought to sneeze out their souls, and before their souls could get back lurking demons were apt to enter the unsouled body; but if any one said “God bless you,” the demons were frightened off. "

― Christopher Hitchens , The Portable Atheist: Essential Readings for the Nonbeliever