"The main purpose which I have had in view in writing this book has been to present an account of Greek philosophy which, within strict limits of brevity, shall be at once authentic and interesting -- _authentic_, as being based on the original works themselves, and not on any secondary sources; _interesting_, as presenting to the ordinary English reader, in language freed as far as possible from technicality and abstruseness, the great thoughts of the greatest men of antiquity on questions of permanent significance and value."