Whenever one finds oneself in unknown places at night where we cannot judge of distance, and where we cannot recognise objects by their shape on account of the darkness, we are in constant danger of forming mistaken judgments as to the objects which present themselves to our notice. Hence that terror, that kind of inward fear experienced by most people on dark nights. This is foundation for the supposed appearances of spectres, or gigantic and terrible forms which so many people profess to have seen. They are generally told that they imagined these things, yet they may really have seen them, and it is quite possible they really saw what they say they did see; for it will always be the case that when we can only estimate the size of an object by the angle it forms in the eye, that object will swell and grow as we approach it; and if the spectator thought it several feet high when it was thirty or forty feet away, it will seem very large indeed when it is a few feet off; this must indeed astonish and alarm the spectator until he touches it and perceives what it is, for as soon as he perceives what it is, the object which seemed so gigantic will suddenly shrink and assume its real size, but if we run away or are afraid to approach, we shall certainly form no other idea of the thing than the image formed in the eye, and we shall have really seen a gigantic figure of alarming size and shape. There is, therefore, a natural ground for the tendency to see ghosts, and these appearances are not merely the creation of the imagination, as the men of science would have us think.--Buffon, Nat. Hist.