Carr stated that he learned about the letter from the anti-Mason, Cardinal José María Caro Rodríguez of Santiago, Chile, the author of "The Mystery of Freemasonry Unveiled" (Hawthorne, California, Christian Book Club of America, 1971). However, Carr's later book, "Satan, Prince of This World" (written in 1959), included the following footnote: "The Keeper of manuscripts recently informed the author that this letter is NOT cataloged in the British Museum Library. It seems strange that a man of Cardinal Rodriguez's knowledge should have said that it WAS in 1925." More recently, the British Museum confirmed in writing to researcher Michael Haupt that such a document has never been in their possession. Pierre-André Taguieff states that Carr gave an ultimate and synthetic account of the "legend," which links together the Illuminati, Mazzini and Pike in a satanic plot for world domination.