It was Lewes, I believe, who compared metaphysics to ghosts by saying that there was no killing either of them; one could only dissipate them by throwing light into the dark places they love to inhabit - to show that nothing is there. Spectres, likewise, are these saintly caricatures of humanity, perambulating metaphysics, the application in corpore vili of Oriental fakirism. Nightmare-literature is the crazy recital of their deeds and sufferings. Pathological phantoms! The state of mind which engenders and cherishes such illusions is a disease, and it has been well said that "you cannot refute a disease." You cannot nail ghosts to the counter.
But a ray of light . . .