The title is his own. Herbert Feigl, the provocateur and the soul (if we may put it so) of modesty, wrote to me some years ago, "I''m more of a catalyst than producer of new and original ideas all my life . . . ", but then he com pleted the self-appraisal: " . . . with just a few exceptions perhaps". We need not argue for the creative nature of catalysis, but will simply remark that there are ''new and original ideas'' in the twenty-four papers selected for this volume, in the extraordinary aperrus of the 25-year-old Feigl in his Vienna dissertation of 1927 on Zufall und Gesetz, in the creative critique and articulation in his classical monograph of 1958 on The ''Mental'' and the ''Physical''; and the reader will want to turn to some of the seventy other titles in our Feigl bibliography appended. Professor Feigl has been a model philosophical worker: above all else, honest, self-aware, open-minded and open-hearted; keenly, devotedly, and even arduously the student of the sciences, he has been a logician and an empiricist. Early on, he brought the Vienna Circle to America, and much later he helped to bring it back to Central Europe. The story of the logical empiricist movement, and of Herbert Feigl''s part in it, has often been told, importantly by Feigl himself in four papers we have included here.