James Cagney never said, “You dirty rat,” but he did "rat out" his favorite movie: “Many people assume that one of those knock-down, drag-'em-outs would be my choice. A discerning critic...can’t understand why I would choose Yankee Doodle Dandy over White Heat and The Public Enemy . The answer is simple, and it derives from George M. Cohan’s comment about himself: Once a song-and-dance man, always a song-and-dance man. In that brief statement, you have my life story; those

I once got an email from an 88-year-old man named George, praising an essay I’d written for The Washington Post . Coincidentally, I had...