[Samuel] Johnson had a peculiar temperament. For a time he was extremely interested in the subject of ghosts. He was so interested in them that he spent several nights in an abandoned house to see if he could meet one. Apparently, he didn’t. There’s a famous passage by the Scottish writer, Thomas Carlyle … in which he talks about Johnson, saying that Johnson wanted to see a ghost. And Carlyle wonders: "What is a ghost? A ghost is a spirit that has taken corporal form and appears for a while among men.” Then Carlyle adds, "How could Johnson not have thought of this when faced with the spectacle of the human multitudes he loved so much in the streets of London, for if a ghost were a spirit that has taken a corporal form for a brief interval, why did it not occur to him that the London multitudes were ghosts, that he himself was a ghost? What is each man but a spirit that has taken corporal form briefly and then disappears? What are men if not ghosts? —A Lecture on Johnson and Boswell by Borges