A biographical sketch of the philosopher whose works form the subject of the following pages has been omitted out of deference to Dimitry Gawronsky’ s excellent treatment of this subject in his contribution to ffhe Philosophy of Ernst Cassirer (Library of Living Philosophers}, under the title of "Cassirers: His Life and Work." Here it suffices to record that Brast Cassirer was born in Breslau, Germany in 1874, and died, after a long life of fertile scholarship, in New York on April 13, 1945. Schopenhauer once wrote that "it is much easier to point out the faults and errors in the work of a great mind than to give a distinct and full exposition of its value." And Schopenhauer was right about, the difficulty of this latter, I mention this not to justify the procedure in this thesis but to give a distinguished comment on its inadequacies. A major aim in this work is to point out two aspects of Cassirer’s philosophy which seem to mark him as an original thinker of the first rank, %e first of these is his incorporation of the modern interest in semiotics -- the science of signs -- into an epistemological standpoint of Critical idealism, The second aspect is one which marks Cassirer’s membership in the Neo-Kantian movement and, as well, his special place in its ranks. This is his extension of Kant’s "Copemican revolution" into fields other than physical science, Commentators have noted that the Neo-Kantians aimed at eliminating the metaphysical elements in Kant and emphasizing the methodological ones. Their activity, with the notable exception of Cassirer, has been directed primarily at the analysis of knowledge in the field of science. Cassirer felt that he had provided for the possibility of knowledge in the other areas of cultural endeavor. I hope I have shown that he did.