“Humbug … I won’t believe it,” is Scrooge’s response when confronted by the ghost of his dead partner Jacob Marley inA Christmas Carol, and just as surely asDickensknows that ghosts are humbugs, so too doesP. T. Barnum, writing a generation later. For Barnum, humbug begins in the Garden of Eden with the temptation of Eve, and permeates all of history, through every age and in every nation, right down to his...