There ought to be room in the retelling of it for the letters Mark Twain and Frederick Douglass exchanged , for the similarities between Invisible Man and Ben Franklin 's Autobiography , for the presence of Charles Chesnutt at the banquet to honor Twain shortly before the latter 's death , and for the monument in Mississippi to the slaves who rode with a band of Confederate irregulars .
Mark Twain and Frederick Douglas exchanged letters because they were friends .