This is Volume I of six in a series on the Nineteenth and Twentieth Century Anglo-American Philosophy. Originally published in 1939, this study looks Charles Peirce, who characterized himself as a mere table of contents, so abstract, a very snarl of twine. The purpose of the following pages is to clarify Peirce in some measure, partly by restatement, partly by filling the lacunae in his thought with what the author thinks are its implications.