The identity of this letter writer remains a mystery. He or she used the return address of the Gilders' home, and may have been a house guest at the time that the Cable circular arrived. Barring a complete and unlikely transformation of hand and signature, it cannot be Clemens's Hartford friend Henry C. Robinson. In addressing the envelope to C. L. Clemens, he or she reveals either ignorance of Clemens's first name, or a ruse to further obfuscate his or her own identity by pretending not to know Clemens's first name.

Richard Watson Gilder was a poet, journalist, editor, and one of the founders of the American Copyright League. His editorial career at the helm of the Century Magazine spanned from the death of his predecessor, J. G. Holland, in 1881 (when Scribner's Magazine became the Century Magazine) to his own death in 1909. He married the painter Helena de Kay, founder of the Society of American Artists, and their home, a converted stable named "the Studio," was a gathering place for artists, players, and writers. Gilder was a founding member of the Authors Club, which was organized in 1882 and incorporated in 1887.