It is wonderful that five thousand years have now elapsed since the creation of the world, and still it is undecided whether or not there has ever been an instance of the spirit of any person appearing after death. All argument is against it; but all belief is for it. – Samuel Johnson, quoted by James Boswell

An idea, like a ghost (according to the common notion of ghosts), must be spoken to a little before it will explain itself. – Attributed to Dickens in Many Thoughts of Many Minds by Henry Southgate, 1862