This is the last of four volumes presenting all of Francis Ellingwood Abbot's major published articles. Any scholar or library interested in American philosophy, religious thought, and social and intellectual history should find this edition of his essays a useful addition to the collection. Francis E. Abbot was a noted American philosopher and champion of Free Religion. He was a member of C.S. Peirce's Metaphysical Club, the first American philosopher to support Charles Darwin, the founding editor of The Index, a founder of the Free Religious Association, and the founding President of the National Liberal League of America. In addition to over six hundred articles, he was the author of Scientific Theism (1885), The Way Out of Agnosticism, Or The Philosophy of Free Religion (1890), and The Syllogistic Philosophy, or Prolegomena to Science (1906).