Frederic Raphael, the English novelist, screenwriter, and man of letters, and Joseph Epstein, the American essayist, short-story writer, and literary critic, exchanged e-mails sporadically over the years, usually commenting on each other's various writings. Then one day in 2009, Raphael wrote to Epstein to suggest that, since they enjoyed a benevolence toward each other unusual among literary men, they begin an exchange of e-mail correspondence on...