If I had as clear an idea of ghosts, as I have of a triangle or a circle, I should not in the least hesitate to affirm that they had been created by God; but as the idea I possess of them is just like the ideas, which my imagination forms of harpies, gryphons, hydras, &c., I cannot consider them as anything but dreams, which differ from God as totally as that which is not differs from that which is.