By Raymond J. de Souza, First Things - In late June, just as I was arriving in Kraków, Poland, for the annual seminar in Catholic social teaching organized by George Weigel, there was a minor kerfuffle about a personal letter that Pope Francis had sent to Fr. James Martin, S.J. It brought to mind another private papal letter from twenty-seven years ago. Private correspondence, selectively shared, is one way that popes choose their interpreters.